FRRouting User Guide¶

Introduction¶

Overview¶

FRR is a fully featured, high performance, free software IP routing suite.

FRR implements all standard routing protocols such as BGP, RIP, OSPF, IS-IS and more (see Feature Matrix), as well as many of their extensions.

FRR is a high performance suite written primarily in C. It can easily handle full Internet routing tables and is suitable for use on hardware ranging from cheap SBCs to commercial grade routers. It is actively used in production by hundreds of companies, universities, research labs and governments.

FRR is distributed under GPLv2, with development modeled after the Linux kernel. Anyone may contribute features, bug fixes, tools, documentation updates, or anything else.

FRR is a fork of Quagga.

How to get FRR¶

The official FRR website is located at https://frrouting.org/ and contains further information, as well as links to additional resources.

Several distributions provide packages for FRR. Check your distribution’s repositories to find out if a suitable version is available.

Up-to-date Debian packages are available at https://deb.frrouting.org/.

For instructions on installing from source, refer to the developer documentation.

About FRR¶

FRR provides IP routing services. Its role in a networking stack is to exchange routing information with other routers, make routing and policy decisions, and inform other layers of these decisions. In the most common scenario, FRR installs routing decisions into the OS kernel, allowing the kernel networking stack to make the corresponding forwarding decisions.

In addition to dynamic routing FRR supports the full range of L3 configuration, including static routes, addresses, router advertisements etc. It has some light L2 functionality as well, but this is mostly left to the platform. This makes it suitable for deployments ranging from small home networks with static routes to Internet exchanges running full Internet tables.

FRR runs on all modern *NIX operating systems, including Linux and the BSDs. Feature support varies by platform; see the Feature Matrix.

System Architecture¶

Traditional routing software is made as a one process program which provides all of the routing protocol functionalities. FRR takes a different approach. FRR is a suite of daemons that work together to build the routing table. Each major protocol is implemented in its own daemon, and these daemons talk to a middleman daemon (zebra), which is responsible for coordinating routing decisions and talking to the dataplane.

This architecture allows for high resiliency, since an error, crash or exploit in one protocol daemon will generally not affect the others. It is also flexible and extensible since the modularity makes it easy to implement new protocols and tie them into the suite. Additionally, each daemon implements a plugin system allowing new functionality to be loaded at runtime.

An illustration of the large scale architecture is given below.

+----+  +----+  +-----+  +----+  +----+  +----+  +-----+
|bgpd|  |ripd|  |ospfd|  |ldpd|  |pbrd|  |pimd|  |.....|
+----+  +----+  +-----+  +----+  +----+  +----+  +-----+
     |       |        |       |       |       |        |
+----v-------v--------v-------v-------v-------v--------v
|                                                      |
|                         Zebra                        |
|                                                      |
+------------------------------------------------------+
       |                    |                   |
       |                    |                   |
+------v------+   +---------v--------+   +------v------+
|             |   |                  |   |             |
| *NIX Kernel |   | Remote dataplane |   | ........... |
|             |   |                  |   |             |
+-------------+   +------------------+   +-------------+

All of the FRR daemons can be managed through a single integrated user interface shell called vtysh. vtysh connects to each daemon through a UNIX domain socket and then works as a proxy for user input. In addition to a unified frontend, vtysh also provides the ability to configure all the daemons using a single configuration file through the integrated configuration mode. This avoids the overhead of maintaining a separate configuration file for each daemon.

FRR is currently currently implementing a new internal configuration system based on YANG data models. When this work is completed, FRR will be a fully programmable routing stack.

Supported Platforms¶

Currently FRR supports GNU/Linux and BSD. Porting FRR to other platforms is not too difficult as platform dependent code should be mostly limited to the Zebra daemon. Protocol daemons are largely platform independent. Please let us know if you can get FRR to run on a platform which is not listed below:

GNU/Linux
FreeBSD
NetBSD
OpenBSD

Versions of these platforms that are older than around 2 years from the point of their original release (in case of GNU/Linux, this is since the kernel’s release on https://kernel.org/) may need some work. Similarly, the following platforms may work with some effort:

Solaris
MacOS

Recent versions of the following compilers are well tested:

GNU’s GCC
LLVM’s Clang
Intel’s ICC

Feature Matrix¶

The following table lists all protocols cross-referenced to all operating systems that have at least CI build tests. Note that for features, only features with system dependencies are included here; if you don’t see the feature you’re interested in, it should be supported on your platform.

Daemon / Feature	Linux	OpenBSD	FreeBSD	NetBSD	Solaris
FRR Core
zebra	Y	Y	Y	Y	Y
VRF	≥4.8	N	N	N	N
MPLS	≥4.5	Y	N	N	N
pbrd (Policy Routing)	Y	N	N	N	N
WAN / Carrier protocols
bgpd (BGP)	Y	Y	Y	Y	Y
VRF / L3VPN	≥4.8 †4.3	CP	CP	CP	CP
EVPN	≥4.18 †4.9	CP	CP	CP	CP
VNC (Virtual Network Control)	CP	CP	CP	CP	CP
Flowspec	CP	CP	CP	CP	CP
ldpd (LDP)	≥4.5	Y	N	N	N
VPWS / PW	N	≥5.8	N	N	N
VPLS	N	≥5.8	N	N	N
nhrpd (NHRP)	Y	N	N	N	N
Link-State Routing
ospfd (OSPFv2)	Y	Y	Y	Y	Y
Segment Routing	≥4.12	N	N	N	N
ospf6d (OSPFv3)	Y	Y	Y	Y	Y
isisd (IS-IS)	Y	Y	Y	Y	Y
Distance-Vector Routing
ripd (RIPv2)	Y	Y	Y	Y	Y
ripngd (RIPng)	Y	Y	Y	Y	Y
babeld (BABEL)	Y	Y	Y	Y	Y
eigrpd (EIGRP)	Y	Y	Y	Y	Y
Multicast Routing
pimd (PIM)	≥4.18	N	Y	Y	Y
SSM (Source Specific)	Y	N	Y	Y	Y
ASM (Any Source)	Y	N	N	N	N
EVPN BUM Forwarding	≥5.0	N	N	N	N
vrrpd (VRRP)	≥5.1	N	N	N	N

The indicators have the following semantics:

Y - daemon/feature fully functional
≥X.X - fully functional with kernel version X.X or newer
†X.X - restricted functionality or impaired performance with kernel version X.X or newer
CP - control plane only (i.e. BGP route server / route reflector)
N - daemon/feature not supported by operating system

Known Kernel Issues¶

Linux < 4.11

v6 Route Replacement - Linux kernels before 4.11 can cause issues with v6 route deletion when you have ECMP routes installed into the kernel. This especially becomes apparent if the route is being transformed from one ECMP path to another.

Supported RFCs¶

FRR implements the following RFCs:

Note

This list is incomplete.

BGP¶

RFC 1771 A Border Gateway Protocol 4 (BGP-4). Y. Rekhter & T. Li. March 1995.
RFC 1965 Autonomous System Confederations for BGP. P. Traina. June 1996.
RFC 1997 BGP Communities Attribute. R. Chandra, P. Traina & T. Li. August 1996.
RFC 2439 BGP Route Flap Damping. C. Villamizar, R. Chandra, R. Govindan. November 1998.
RFC 2545 Use of BGP-4 Multiprotocol Extensions for IPv6 Inter-Domain Routing. P. Marques, F. Dupont. March 1999.
RFC 2796 BGP Route Reflection An alternative to full mesh IBGP. T. Bates & R. Chandrasekeran. June 1996.
RFC 2842 Capabilities Advertisement with BGP-4. R. Chandra, J. Scudder. May 2000.
RFC 2858 Multiprotocol Extensions for BGP-4. T. Bates, Y. Rekhter, R. Chandra, D.
RFC 3107 Carrying Label Information in BGP-4. Y. Rekhter & E. Rosen. May 2001.
RFC 3765 NOPEER Community for Border Gateway Protocol (BGP) Route Scope Control. G.Huston, April 2001.
RFC 4271 A Border Gateway Protocol 4 (BGP-4). Updates RFC1771. Y. Rekhter, T. Li & S. Hares. January 2006.
RFC 4364 BGP/MPLS IP Virtual Private Networks (VPNs). Y. Rekhter. Feb 2006.
RFC 4659 BGP-MPLS IP Virtual Private Network (VPN) Extension for IPv6 VPN. J. De Clercq, D. Ooms, M. Carugi, F. Le Faucheur. September 2006.
RFC 5004 Avoid BGP Best Path Transitions from One External to Another. E. Chen & S. Sangli. September 2007 (Partial support).
RFC 5082 The Generalized TTL Security Mechanism (GTSM). V. Gill, J. Heasley, D. Meyer, P. Savola, C. Pingnataro. October 2007.
RFC 5575 Dissemination of Flow Specification Rules. P. Marques, N. Sheth, R. Raszuk, B. Greene, J. Mauch, D. McPherson. August 2009
RFC 6810 The Resource Public Key Infrastructure (RPKI) to Router Protocol. R. Bush, R. Austein. January 2013.
RFC 6811 BGP Prefix Origin Validation. P. Mohapatra, J. Scudder, D. Ward, R. Bush, R. Austein. January 2013.
RFC 7611 BGP ACCEPT_OWN Community Attribute. J. Uttaro, P. Mohapatra, D. Smith, R. Raszuk, J. Scudder. August 2015.
RFC 7999 BLACKHOLE Community. T. King, C. Dietzel, J. Snijders, G. Doering, G. Hankins. Oct 2016.
RFC 8092 BGP Large Communities Attribute. J. Heitz, Ed., J. Snijders, Ed, K. Patel, I. Bagdonas, N. Hilliard. February 2017
RFC 8195 Use of BGP Large Communities. J. Snijders, J. Heasley, M. Schmidt, June 2017
RFC 8212 Default External BGP (EBGP) Route Propagation Behavior without Policies. J. Mauch, J. Snijders, G. Hankins. July 2017
RFC 8277 Using BGP to Bind MPLS Labels to Address Prefixes. E. Rosen. October 2017

OSPF¶

RFC 2328 OSPF Version 2. J. Moy. April 1998.
RFC 2370 The OSPF Opaque LSA Option R. Coltun. July 1998.
RFC 3101 The OSPF Not-So-Stubby Area (NSSA) Option P. Murphy. January 2003.
RFC 2740 OSPF for IPv6. R. Coltun, D. Ferguson, J. Moy. December 1999.
RFC 3137 OSPF Stub Router Advertisement, A. Retana, L. Nguyen, R. White, A. Zinin, D. McPherson. June 2001

ISIS¶

RIP¶

RFC 1058 Routing Information Protocol. C.L. Hedrick. Jun-01-1988.
RFC 2082 RIP-2 MD5 Authentication. F. Baker, R. Atkinson. January 1997.
RFC 2453 RIP Version 2. G. Malkin. November 1998.
RFC 2080 RIPng for IPv6. G. Malkin, R. Minnear. January 1997.

PIM¶

BFD¶

RFC 5880 Bidirectional Forwarding Detection (BFD), D. Katz, D. Ward. June 2010
RFC 5881 Bidirectional Forwarding Detection (BFD) for IPv4 and IPv6 (Single Hop), D. Katz, D. Ward. June 2010
RFC 5883 Bidirectional Forwarding Detection (BFD) for Multihop Paths, D. Katz, D. Ward. June 2010

MPLS¶

RFC 2858 Multiprotocol Extensions for BGP-4. T. Bates, Y. Rekhter, R. Chandra, D. Katz. June 2000.
RFC 4364 BGP/MPLS IP Virtual Private Networks (VPNs). Y. Rekhter. Feb 2006.
RFC 4447 Pseudowire Setup and Maintenance Using the Label Distribution Protocol (LDP), L. Martini, E. Rosen, N. El-Aawar, T. Smith, and G. Heron. April 2006.
RFC 4659 BGP-MPLS IP Virtual Private Network (VPN) Extension for IPv6 VPN. J. De Clercq, D. Ooms, M. Carugi, F. Le Faucheur. September 2006
RFC 4762 Virtual Private LAN Service (VPLS) Using Label Distribution Protocol (LDP) Signaling, M. Lasserre and V. Kompella. January 2007.
RFC 5036 LDP Specification, L. Andersson, I. Minei, and B. Thomas. October 2007.
RFC 5561 LDP Capabilities, B. Thomas, K. Raza, S. Aggarwal, R. Aggarwal, and JL. Le Roux. July 2009.
RFC 5918 Label Distribution Protocol (LDP) ‘Typed Wildcard’ Forward Equivalence Class (FEC), R. Asati, I. Minei, and B. Thomas. August 2010.
RFC 5919 Signaling LDP Label Advertisement Completion, R. Asati, P. Mohapatra, E. Chen, and B. Thomas. August 2010.
RFC 6667 LDP ‘Typed Wildcard’ Forwarding Equivalence Class (FEC) for PWid and Generalized PWid FEC Elements, K. Raza, S. Boutros, and C. Pignataro. July 2012.
RFC 6720 The Generalized TTL Security Mechanism (GTSM) for the Label Distribution Protocol (LDP), C. Pignataro and R. Asati. August 2012.
RFC 7552 Updates to LDP for IPv6, R. Asati, C. Pignataro, K. Raza, V. Manral, and R. Papneja. June 2015.

SNMP¶

When SNMP support is enabled, the following RFCs are also supported:

RFC 1227 SNMP MUX protocol and MIB. M.T. Rose. May-01-1991.
RFC 1657 Definitions of Managed Objects for the Fourth Version of the Border Gateway Protocol (BGP-4) using SMIv2. S. Willis, J. Burruss, J. Chu, Editor. July 1994.
RFC 1724 RIP Version 2 MIB Extension. G. Malkin & F. Baker. November 1994.
RFC 1850 OSPF Version 2 Management Information Base. F. Baker, R. Coltun. November 1995.
RFC 2741 Agent Extensibility (AgentX) Protocol. M. Daniele, B. Wijnen. January 2000.

Mailing Lists¶

Italicized lists are private.

Topic	List
Development	dev@lists.frrouting.org
Users & Operators	frog@lists.frrouting.org
Announcements	announce@lists.frrouting.org
Security	security@lists.frrouting.org
Technical Steering Committee	tsc@lists.frrouting.org

The Development list is used to discuss and document general issues related to project development and governance. The public Slack instance and weekly technical meetings provide a higher bandwidth channel for discussions. The results of such discussions are reflected in updates, as appropriate, to code (i.e., merges), GitHub issues tracked issues, and for governance or process changes, updates to the Development list and either this file or information posted at FRR.

Bug Reports¶

For information on reporting bugs, please see Reporting Bugs.

Installation¶

This section covers the basics of building, installing and setting up FRR.

From Packages¶

The project publishes packages for Red Hat, Centos, Debian and Ubuntu on the GitHub releases. page. External contributors offer packages for many other platforms including *BSD, Alpine, Gentoo, Docker, and others. There is currently no documentation on how to use those but we hope to add it soon.

From Snapcraft¶

In addition to traditional packages the project also builds and publishes universal Snap images, available at https://snapcraft.io/frr.

From Source¶

Building FRR from source is the best way to ensure you have the latest features and bug fixes. Details for each supported platform, including dependency package listings, permissions, and other gotchas, are in the developer’s documentation. This section provides a brief overview on the process.

Getting the Source¶

FRR’s source is available on the project GitHub page.

git clone https://github.com/FRRouting/frr.git

When building from Git there are several branches to choose from. The master branch is the primary development branch. It should be considered unstable. Each release has its own branch named stable/X.X, where X.X is the release version.

In addition, release tarballs are published on the GitHub releases page here.

Configuration¶

FRR has an excellent configure script which automatically detects most host configurations. There are several additional configure options to customize the build to include or exclude specific features and dependencies.

First, update the build system. Change into your FRR source directory and issue:

./bootstrap.sh

This will install any missing build scripts and update the Autotools configuration. Once this is done you can move on to choosing your configuration options from the list below.

--enable-tcmalloc¶: Enable the alternate malloc library. In some cases this is faster and more efficient, in some cases it is not.

--disable-doc¶: Do not build any documentation, including this one.

--enable-doc-html¶: From the documentation build html docs as well in addition to the normal output.

--disable-zebra¶: Do not build zebra daemon. This generally only be useful in a scenario where you are building bgp as a standalone server.

--disable-ripd¶: Do not build ripd.

--disable-ripngd¶: Do not build ripngd.

--disable-ospfd¶: Do not build ospfd.

--disable-ospf6d¶: Do not build ospf6d.

--disable-bgpd¶: Do not build bgpd.

--disable-ldpd¶: Do not build ldpd.

--disable-nhrpd¶: Do not build nhrpd.

--disable-eigrpd¶: Do not build eigrpd.

--disable-babeld¶: Do not build babeld.

--disable-watchfrr¶: Do not build watchfrr. Watchfrr is used to integrate daemons into startup/shutdown software available on your machine. This is needed for systemd integration, if you disable watchfrr you cannot have any systemd integration.

--enable-systemd¶: Build watchfrr with systemd integration, this will allow FRR to communicate with systemd to tell systemd if FRR has come up properly.

--disable-pimd¶: Turn off building of pimd. On some BSD platforms pimd will not build properly due to lack of kernel support.

--disable-vrrpd¶: Turn off building of vrrpd. Linux is required for vrrpd support; other platforms are not supported.

--disable-pbrd¶: Turn off building of pbrd. This daemon currently requires linux in order to function properly.

--enable-sharpd¶: Turn on building of sharpd. This daemon facilitates testing of FRR and can also be used as a quick and easy route generator.

--disable-staticd¶: Do not build staticd. This daemon is necessary if you want static routes.

--disable-bfdd¶: Do not build bfdd.

--disable-bgp-announce¶: Make bgpd which does not make bgp announcements at all. This feature is good for using bgpd as a BGP announcement listener.

--disable-bgp-vnc¶: Turn off bgpd’s ability to use VNC.

--enable-datacenter¶: Enable system defaults to work as if in a Data Center. See defaults.h for what is changed by this configure option.

--enable-snmp¶: Enable SNMP support. By default, SNMP support is disabled.

--disable-ospfapi¶: Disable support for OSPF-API, an API to interface directly with ospfd. OSPF-API is enabled if –enable-opaque-lsa is set.

--disable-ospfclient¶: Disable building of the example OSPF-API client.

--disable-isisd¶: Do not build isisd.

--disable-fabricd¶: Do not build fabricd.

--enable-isis-topology¶: Enable IS-IS topology generator.

--enable-realms¶: Enable the support of Linux Realms. Convert tag values from 1-255 into a realm value when inserting into the Linux kernel. Then routing policy can be assigned to the realm. See the tc man page.

--disable-rtadv¶: Disable support IPV6 router advertisement in zebra.

--enable-gcc-rdynamic¶: Pass the -rdynamic option to the linker driver. This is in most cases necessary for getting usable backtraces. This option defaults to on if the compiler is detected as gcc, but giving an explicit enable/disable is suggested.

--disable-backtrace¶: Controls backtrace support for the crash handlers. This is autodetected by default. Using the switch will enforce the requested behaviour, failing with an error if support is requested but not available. On BSD systems, this needs libexecinfo, while on glibc support for this is part of libc itself.

--enable-dev-build¶: Turn on some options for compiling FRR within a development environment in mind. Specifically turn on -g3 -O0 for compiling options and add inclusion of grammar sandbox.

--enable-fuzzing¶: Turn on some compile options to allow you to run fuzzing tools against the system. This flag is intended as a developer only tool and should not be used for normal operations.

--disable-snmp¶: Build without SNMP support.

--disable-vtysh¶: Build without VTYSH.

--enable-fpm¶: Build with FPM module support.

--enable-numeric-version¶: Alpine Linux does not allow non-numeric characters in the version string. With this option, we provide a way to strip out these characters for APK dev package builds.

--enable-multipath=X¶: Compile FRR with up to X way ECMP supported. This number can be from 0-999. For backwards compatibility with older configure options when setting X = 0, we will build FRR with 64 way ECMP. This is needed because there are hardcoded arrays that FRR builds towards, so we need to know how big to make these arrays at build time. Additionally if this parameter is not passed in FRR will default to 16 ECMP.

--enable-shell-access¶: Turn on the ability of FRR to access some shell options( telnet/ssh/bash/etc. ) from vtysh itself. This option is considered extremely unsecure and should only be considered for usage if you really really know what you are doing.

--enable-gcov¶: Code coverage reports from gcov require adjustments to the C and LD flags. With this option, gcov instrumentation is added to the build and coverage reports are created during execution. The check-coverage make target is also created to ease report uploading to codecov.io. The upload requires the COMMIT (git hash) and TOKEN (codecov upload token) environment variables be set.

--enable-config-rollbacks¶: Build with configuration rollback support. Requires SQLite3.

--enable-confd=<dir>¶: Build the ConfD northbound plugin. Look for the libconfd libs and headers in dir.

--enable-sysrepo¶: Build the Sysrepo northbound plugin.

--enable-time-check XXX¶: When this is enabled with a XXX value in microseconds, any thread that runs for over this value will cause a warning to be issued to the log. If you do not specify any value or don’t include this option then the default time is 5 seconds. If –disable-time-check is specified then no warning is issued for any thread run length.

--disable-cpu-time¶: Disable cpu process accounting, this command also disables the show thread cpu command. If this option is disabled, –enable-time-check is ignored. This disabling of cpu time effectively means that the getrusage call is skipped. Since this is a process switch into the kernel, systems with high FRR load might see improvement in behavior. Be aware that show thread cpu is considered a good data gathering tool from the perspective of developers.

You may specify any combination of the above options to the configure script. By default, the executables are placed in /usr/local/sbin and the configuration files in /usr/local/etc. The /usr/local/ installation prefix and other directories may be changed using the following options to the configuration script.

--prefix <prefix>¶: Install architecture-independent files in prefix [/usr/local].

--sysconfdir <dir>¶: Look for configuration files in dir [prefix/etc]. Note that sample configuration files will be installed here.

--localstatedir <dir>¶: Configure zebra to use dir for local state files, such as pid files and unix sockets.

--with-yangmodelsdir <dir>¶: Look for YANG modules in dir [prefix/share/yang]. Note that the FRR YANG modules will be installed here.

Python dependency, documentation and tests¶

FRR’s documentation and basic unit tests heavily use code written in Python. Additionally, FRR ships Python extensions written in C which are used during its build process.

To this extent, FRR needs the following:

an installation of CPython, preferably version 3.2 or newer (2.7 works but is end of life and will stop working at some point.)
development files (mostly headers) for that version of CPython
an installation of sphinx for that version of CPython, to build the documentation
an installation of pytest for that version of CPython, to run the unit tests

The sphinx and pytest dependencies can be avoided by not building documentation / not running make check, but the CPython dependency is a hard dependency of the FRR build process (for the clippy tool.)

Least-Privilege Support¶

Additionally, you may configure zebra to drop its elevated privileges shortly after startup and switch to another user. The configure script will automatically try to configure this support. There are three configure options to control the behaviour of FRR daemons.

--enable-user <user>¶: Switch to user user shortly after startup, and run as user `user in normal operation.

--enable-group <user>¶: Switch real and effective group to group shortly after startup.

--enable-vty-group <group>¶: Create Unix Vty sockets (for use with vtysh) with group ownership set to group. This allows one to create a separate group which is restricted to accessing only the vty sockets, hence allowing one to delegate this group to individual users, or to run vtysh setgid to this group.

The default user and group which will be configured is ‘frr’ if no user or group is specified. Note that this user or group requires write access to the local state directory (see --localstatedir) and requires at least read access, and write access if you wish to allow daemons to write out their configuration, to the configuration directory (see --sysconfdir).

On systems which have the ‘libcap’ capabilities manipulation library (currently only Linux), FRR will retain only minimal capabilities required and will only raise these capabilities for brief periods. On systems without libcap, FRR will run as the user specified and only raise its UID to 0 for brief periods.

Linux Notes¶

There are several options available only to GNU/Linux systems. If you use GNU/Linux, make sure that the current kernel configuration is what you want. FRR will run with any kernel configuration but some recommendations do exist.

CONFIG_NETLINK: Kernel/User Netlink socket. This enables an advanced interface between the Linux kernel and zebra (Kernel Interface).
CONFIG_RTNETLINK: This makes it possible to receive Netlink routing messages. If you specify this option, zebra can detect routing information updates directly from the kernel (Kernel Interface).
CONFIG_IP_MULTICAST: This option enables IP multicast and should be specified when you use ripd (RIP) or ospfd (OSPFv2) because these protocols use multicast.

Linux sysctl settings and kernel modules¶

There are several kernel parameters that impact overall operation of FRR when using Linux as a router. Generally these parameters should be set in a sysctl related configuration file, e.g., /etc/sysctl.conf on Ubuntu based systems and a new file /etc/sysctl.d/90-routing-sysctl.conf on Centos based systems. Additional kernel modules are also needed to support MPLS forwarding.

IPv4 and IPv6 forwarding

The following are set to enable IP forwarding in the kernel:

net.ipv4.conf.all.forwarding=1
net.ipv6.conf.all.forwarding=1

MPLS forwarding

Basic MPLS support was introduced in the kernel in version 4.1 and additional capability was introduced in 4.3 and 4.5. For some general information on Linux MPLS support, see https://www.netdevconf.org/1.1/proceedings/slides/prabhu-mpls-tutorial.pdf. The following modules should be loaded to support MPLS forwarding, and are generally added to a configuration file such as /etc/modules-load.d/modules.conf:

# Load MPLS Kernel Modules
mpls_router
mpls_iptunnel

The following is an example to enable MPLS forwarding in the kernel, typically by editing /etc/sysctl.conf:

# Enable MPLS Label processing on all interfaces
net.mpls.conf.eth0.input=1
net.mpls.conf.eth1.input=1
net.mpls.conf.eth2.input=1
net.mpls.platform_labels=100000

Make sure to add a line equal to net.mpls.conf.<if>.input for each interface ‘<if>’ used with MPLS and to set labels to an appropriate value.

VRF forwarding

General information on Linux VRF support can be found in https://www.kernel.org/doc/Documentation/networking/vrf.txt. Kernel support for VRFs was introduced in 4.3 and improved upon through 4.13, which is the version most used in FRR testing (as of June 2018). Additional background on using Linux VRFs and kernel specific features can be found in http://schd.ws/hosted_files/ossna2017/fe/vrf-tutorial-oss.pdf.

The following impacts how BGP TCP sockets are managed across VRFs:

net.ipv4.tcp_l3mdev_accept=0

With this setting a BGP TCP socket is opened per VRF. This setting ensures that other TCP services, such as SSH, provided for non-VRF purposes are blocked from VRF associated Linux interfaces.

net.ipv4.tcp_l3mdev_accept=1

With this setting a single BGP TCP socket is shared across the system. This setting exposes any TCP service running on the system, e.g., SSH, to all VRFs. Generally this setting is not used in environments where VRFs are used to support multiple administrative groups.

Important note as of June 2018, Kernel versions 4.14-4.18 have a known bug where VRF-specific TCP sockets are not properly handled. When running these kernel versions, if unable to establish any VRF BGP adjacencies, either downgrade to 4.13 or set ‘net.ipv4.tcp_l3mdev_accept=1’. The fix for this issue is planned to be included in future kernel versions. So upgrading your kernel may also address this issue.

Building¶

Once you have chosen your configure options, run the configure script and pass the options you chose:

./configure \
    --prefix=/usr \
    --enable-exampledir=/usr/share/doc/frr/examples/ \
    --localstatedir=/var/run/frr \
    --sbindir=/usr/lib/frr \
    --sysconfdir=/etc/frr \
    --enable-pimd \
    --enable-watchfrr \
    ...

After configuring the software, you are ready to build and install it in your system.

make && sudo make install

If everything finishes successfully, FRR should be installed. You should now skip to the section on Basic Setup.

Basic Setup¶

After installing FRR, some basic configuration must be completed before it is ready to use.

Daemons Configuration File¶

After a fresh install, starting FRR will do nothing. This is because daemons must be explicitly enabled by editing a file in your configuration directory. This file is usually located at /etc/frr/daemons and determines which daemons are activated when issuing a service start / stop command via init or systemd. The file initially looks like this:

zebra=no
bgpd=no
ospfd=no
ospf6d=no
ripd=no
ripngd=no
isisd=no
pimd=no
ldpd=no
nhrpd=no
eigrpd=no
babeld=no
sharpd=no
staticd=no
pbrd=no
bfdd=no
fabricd=no

#
# If this option is set the /etc/init.d/frr script automatically loads
# the config via "vtysh -b" when the servers are started.
# Check /etc/pam.d/frr if you intend to use "vtysh"!
#
vtysh_enable=yes
zebra_options=" -s 90000000 --daemon -A 127.0.0.1"
bgpd_options="   --daemon -A 127.0.0.1"
ospfd_options="  --daemon -A 127.0.0.1"
ospf6d_options=" --daemon -A ::1"
ripd_options="   --daemon -A 127.0.0.1"
ripngd_options=" --daemon -A ::1"
isisd_options="  --daemon -A 127.0.0.1"
pimd_options="  --daemon -A 127.0.0.1"
ldpd_options="  --daemon -A 127.0.0.1"
nhrpd_options="  --daemon -A 127.0.0.1"
eigrpd_options="  --daemon -A 127.0.0.1"
babeld_options="  --daemon -A 127.0.0.1"
sharpd_options="  --daemon -A 127.0.0.1"
staticd_options="  --daemon -A 127.0.0.1"
pbrd_options="  --daemon -A 127.0.0.1"
bfdd_options="  --daemon -A 127.0.0.1"
fabricd_options="  --daemon -A 127.0.0.1"

#MAX_FDS=1024
# The list of daemons to watch is automatically generated by the init script.
#watchfrr_options=""

# for debugging purposes, you can specify a "wrap" command to start instead
# of starting the daemon directly, e.g. to use valgrind on ospfd:
#   ospfd_wrap="/usr/bin/valgrind"
# or you can use "all_wrap" for all daemons, e.g. to use perf record:
#   all_wrap="/usr/bin/perf record --call-graph -"
# the normal daemon command is added to this at the end.

Breaking this file down:

bgpd=yes

To enable a particular daemon, simply change the corresponding ‘no’ to ‘yes’. Subsequent service restarts should start the daemon.

vtysh_enable=yes

As the comment says, this causes VTYSH to apply configuration when starting the daemons. This is useful for a variety of reasons touched on in the VTYSH documentation and should generally be enabled.

MAX_FDS=1024

This allows the operator to control the number of open file descriptors each daemon is allowed to start with. The current assumed value on most operating systems is 1024. If the operator plans to run bgp with several thousands of peers than this is where we would modify FRR to allow this to happen.

zebra_options=" -s 90000000 --daemon -A 127.0.0.1"
bgpd_options="   --daemon -A 127.0.0.1"
...

The next set of lines controls what options are passed to daemons when started from the service script. Usually daemons will have --daemon and -A <address> specified in order to daemonize and listen for VTY commands on a particular address.

The remaining file content regarding watchfrr_options and *_wrap settings should not normally be needed; refer to the comments in case they are.

Services¶

FRR daemons have their own terminal interface or VTY. After installation, it’s a good idea to setup each daemon’s port number to connect to them. To do this add the following entries to /etc/services.

zebrasrv      2600/tcp                 # zebra service
zebra         2601/tcp                 # zebra vty
ripd          2602/tcp                 # RIPd vty
ripngd        2603/tcp                 # RIPngd vty
ospfd         2604/tcp                 # OSPFd vty
bgpd          2605/tcp                 # BGPd vty
ospf6d        2606/tcp                 # OSPF6d vty
ospfapi       2607/tcp                 # ospfapi
isisd         2608/tcp                 # ISISd vty
babeld        2609/tcp                 # BABELd vty
nhrpd         2610/tcp                 # nhrpd vty
pimd          2611/tcp                 # PIMd vty
ldpd          2612/tcp                 # LDPd vty
eigprd        2613/tcp                 # EIGRPd vty
bfdd          2617/tcp                 # bfdd vty
fabricd       2618/tcp                 # fabricd vty
vrrpd         2619/tcp                 # vrrpd vty

If you use a FreeBSD newer than 2.2.8, the above entries are already added to /etc/services so there is no need to add it. If you specify a port number when starting the daemon, these entries may not be needed.

You may need to make changes to the config files in /etc/frr.

Systemd¶

Although not installed when installing from source, FRR provides a service file for use with systemd. It is located in tools/frr.service in the Git repository. If systemctl status frr.service indicates that the FRR service is not found, copy the service file from the Git repository into your preferred location. A good place is usually /etc/systemd/system/.

After issuing a systemctl daemon-reload, you should be able to start the FRR service via systemctl start frr. If this fails, or no daemons are started. check the journalctl logs for an indication of what went wrong.

Operations¶

This section covers a few common operational tasks and how to perform them.

Restarting¶

Restarting kills all running FRR daemons and starts them again. Any unsaved configuration will be lost.

service frr restart

Note

Alternatively, you can invoke the init script directly:

/etc/init.d/frr restart

Or, if using systemd:

systemctl restart frr

Reloading¶

Reloading applies the differential between on-disk configuration and the current effective configuration of running FRR processes. This includes starting daemons that were previously stopped and any changes made to individual or unified daemon configuration files.

service frr reload

Note

Alternatively, you can invoke the init script directly:

/etc/init.d/frr reload

Or, if using systemd:

systemctl reload frr

Starting a new daemon¶

Suppose bgpd and zebra are running, and you wish to start pimd. In /etc/frr/daemons make the following change:

- pimd=no
+ pimd=yes

Then perform a reload.

Currently there is no way to stop or restart an individual daemon. This is because FRR’s monitoring program cannot currently distinguish between a crashed / killed daemon versus one that has been intentionally stopped or restarted. The closest that can be achieved is to remove all configuration for the daemon, and set its line in /etc/frr/daemons to =no. Once this is done, the daemon will be stopped the next time FRR is restarted.

Basics¶

Basic Commands¶

The following sections discuss commands common to all the routing daemons.

Config Commands¶

In a config file, you can write the debugging options, a vty’s password, routing daemon configurations, a log file name, and so forth. This information forms the initial command set for a routing beast as it is starting.

Config files are generally found in /etc/frr.

Each of the daemons has its own config file. The daemon name plus .conf is the default config file name. For example, zebra’s default config file name is zebra.conf. You can specify a config file using the -f or --config_file options when starting the daemon.

Basic Config Commands¶

hostname HOSTNAME¶: Set hostname of the router.

[no] password PASSWORD¶: Set password for vty interface. The no form of the command deletes the password. If there is no password, a vty won’t accept connections.

[no] enable password PASSWORD¶: Set enable password. The no form of the command deletes the enable password.

[no] log trap LEVEL¶: These commands are deprecated and are present only for historical compatibility. The log trap command sets the current logging level for all enabled logging destinations, and it sets the default for all future logging commands that do not specify a level. The normal default logging level is debugging. The no form of the command resets the default level for future logging commands to debugging, but it does not change the logging level of existing logging destinations.

[no] log stdout LEVEL¶: Enable logging output to stdout. If the optional second argument specifying the logging level is not present, the default logging level (typically debugging) will be used. The no form of the command disables logging to stdout. The LEVEL argument must have one of these values: emergencies, alerts, critical, errors, warnings, notifications, informational, or debugging. Note that the existing code logs its most important messages with severity errors.

[no] log file [FILENAME [LEVEL]]¶

If you want to log into a file, please specify filename as in this example:

log file /var/log/frr/bgpd.log informational

If the optional second argument specifying the logging level is not present, the default logging level (typically debugging, but can be changed using the deprecated log trap command) will be used. The no form of the command disables logging to a file.

Note

If you do not configure any file logging, and a daemon crashes due to a signal or an assertion failure, it will attempt to save the crash information in a file named /var/tmp/frr.<daemon name>.crashlog. For security reasons, this will not happen if the file exists already, so it is important to delete the file after reporting the crash information.

[no] log syslog [LEVEL]¶: Enable logging output to syslog. If the optional second argument specifying the logging level is not present, the default logging level (typically debugging, but can be changed using the deprecated log trap command) will be used. The no form of the command disables logging to syslog.

[no] log monitor [LEVEL]¶: Enable logging output to vty terminals that have enabled logging using the terminal monitor command. By default, monitor logging is enabled at the debugging level, but this command (or the deprecated log trap command) can be used to change the monitor logging level. If the optional second argument specifying the logging level is not present, the default logging level (typically debugging) will be used. The no form of the command disables logging to terminal monitors.

[no] log facility [FACILITY]¶: This command changes the facility used in syslog messages. The default facility is daemon. The no form of the command resets the facility to the default daemon facility.

[no] log record-priority¶: To include the severity in all messages logged to a file, to stdout, or to a terminal monitor (i.e. anything except syslog), use the log record-priority global configuration command. To disable this option, use the no form of the command. By default, the severity level is not included in logged messages. Note: some versions of syslogd (including Solaris) can be configured to include the facility and level in the messages emitted.

[no] log timestamp precision [(0-6)]¶

This command sets the precision of log message timestamps to the given number of digits after the decimal point. Currently, the value must be in the range 0 to 6 (i.e. the maximum precision is microseconds). To restore the default behavior (1-second accuracy), use the no form of the command, or set the precision explicitly to 0.

log timestamp precision 3

In this example, the precision is set to provide timestamps with millisecond accuracy.

[no] log commands¶: This command enables the logging of all commands typed by a user to all enabled log destinations. The note that logging includes full command lines, including passwords. If the daemon startup option –command-log-always is used to start the daemon then this command is turned on by default and cannot be turned off and the [no] form of the command is dissallowed.

[no] log-filter WORD [DAEMON]¶: This command forces logs to be filtered on a specific string. A log message will only be printed if it matches on one of the filters in the log-filter table. Can be daemon independent.

Note

Log filters help when you need to turn on debugs that cause significant load on the system (enabling certain debugs can bring FRR to a halt). Log filters prevent this but you should still expect a small performance hit due to filtering each of all those logs.

log-filter clear [DAEMON]¶: This command clears all current filters in the log-filter table. Can be daemon independent.

service password-encryption¶: Encrypt password.

service advanced-vty¶: Enable advanced mode VTY.

service terminal-length (0-512)¶: Set system wide line configuration. This configuration command applies to all VTY interfaces.

line vty¶: Enter vty configuration mode.

banner motd default¶: Set default motd string.

banner motd file FILE¶: Set motd string from file. The file must be in directory specified under --sysconfdir.

banner motd line LINE¶: Set motd string from an input.

no banner motd¶: No motd banner string will be printed.

exec-timeout MINUTE [SECOND]¶: Set VTY connection timeout value. When only one argument is specified it is used for timeout value in minutes. Optional second argument is used for timeout value in seconds. Default timeout value is 10 minutes. When timeout value is zero, it means no timeout.

no exec-timeout¶: Do not perform timeout at all. This command is as same as exec-timeout 0 0.

access-class ACCESS-LIST¶: Restrict vty connections with an access list.

Sample Config File¶

Below is a sample configuration file for the zebra daemon.

!
! Zebra configuration file
!
frr version 6.0
frr defaults traditional
!
hostname Router
password zebra
enable password zebra
!
log stdout
!
!

! and # are comment characters. If the first character of the word is one of the comment characters then from the rest of the line forward will be ignored as a comment.

password zebra!password

If a comment character is not the first character of the word, it’s a normal character. So in the above example ! will not be regarded as a comment and the password is set to zebra!password.

Configuration versioning, profiles and upgrade behavior¶

All frr daemons share a mechanism to specify a configuration profile and version for loading and saving configuration. Specific configuration settings take different default values depending on the selected profile and version.

While the profile can be selected by user configuration and will remain over upgrades, frr will always write configurations using its current version. This means that, after upgrading, a write file may write out a slightly different configuration than what was read in.

Since the previous configuration is loaded with its version’s defaults, but the new configuration is written with the new defaults, any default that changed between versions will result in an appropriate configuration entry being written out. FRRouting configuration is sticky, staying consistent over upgrades. Changed defaults will only affect new configuration.

Note that the loaded version persists into interactive configuration sessions. Commands executed in an interactive configuration session are no different from configuration loaded at startup. This means that when, say, you configure a new BGP peer, the defaults used for configuration are the ones selected by the last frr version command.

Warning

Saving the configuration does not bump the daemons forward to use the new version for their defaults, but restarting them will, since they will then apply the new frr version command that was written out. Manually execute the frr version command in show running-config to avoid this intermediate state.

This is visible in show running-config:

Current configuration:
!
! loaded from 6.0
frr version 6.1-dev
frr defaults traditional
!

If you save and then restart with this configuration, the old defaults will no longer apply. Similarly, you could execute frr version 6.1-dev, causing the new defaults to apply and the loaded from 6.0 comment to disappear.

Profiles¶

frr provides configuration profiles to adapt its default settings to various usage scenarios. Currently, the following profiles are implemented:

traditional - reflects defaults adhering mostly to IETF standards or common practices in wide-area internet routing.
datacenter - reflects a single administrative domain with intradomain links using aggressive timers.

Your distribution/installation may pre-set a profile through the -F command line option on all daemons. All daemons must be configured for the same profile. The value specified on the command line is only a pre-set and any frr defaults statement in the configuration will take precedence.

Note

The profile must be the same across all daemons. Mismatches may result in undefined behavior.

You can freely switch between profiles without causing any interruption or configuration changes. All settings remain at their previous values, and show running-configuration output will have new output listing the previous default values as explicit configuration. New configuration, e.g. adding a BGP peer, will use the new defaults. To apply the new defaults for existing configuration, the previously-invisible old defaults that are now shown must be removed from the configuration.

Upgrade practices for interactive configuration¶

If you configure frr interactively and use the configuration writing functionality to make changes persistent, the following recommendations apply in regards to upgrades:

Skipping major versions should generally work but is still inadvisable. To avoid unneeded issue, upgrade one major version at a time and write out the configuration after each update.
After installing a new frr version, check the configuration for differences against your old configuration. If any defaults changed that affect your setup, lines may appear or disappear. If a new line appears, it was previously the default (or not supported) and is now neccessary to retain previous behavior. If a line disappears, it previously wasn’t the default, but now is, so it is no longer necessary.
Check the log files for deprecation warnings by using grep -i deprecat.
After completing each upgrade, save the configuration and either restart frr or execute frr version <CURRENT> to ensure defaults of the new version are fully applied.

Upgrade practices for autogenerated configuration¶

When using frr with generated configurations (e.g. Ansible, Puppet, etc.), upgrade considerations differ somewhat:

Always write out a frr version statement in the configurations you generate. This ensures that defaults are applied consistently.
Try to not run more distinct versions of frr than necessary. Each version may need to be checked individually. If running a mix of older and newer installations, use the oldest version for the frr version statement.
When rolling out upgrades, generate a configuration as usual with the old version identifier and load it. Check for any differences or deprecation warnings. If there are differences in the configuration, propagate these back to the configuration generator to minimize relying on actual default values.
After the last installation of an old version is removed, change the configuration generation to a newer frr version as appropriate. Perform the same checks as when rolling out upgrades.

Terminal Mode Commands¶

write terminal¶: Displays the current configuration to the vty interface.

write file¶: Write current configuration to configuration file.

configure [terminal]¶: Change to configuration mode. This command is the first step to configuration.

terminal length (0-512)¶: Set terminal display length to (0-512). If length is 0, no display control is performed.

who¶: Show a list of currently connected vty sessions.

list¶: List all available commands.

show version¶: Show the current version of frr and its build host information.

show logging¶: Shows the current configuration of the logging system. This includes the status of all logging destinations.

show log-filter¶: Shows the current log filters applied to each daemon.

show memory¶

Show information on how much memory is used for which specific things in frr. Output may vary depending on system capabilities but will generally look something like this:

frr# show memory
System allocator statistics:
  Total heap allocated:  1584 KiB
  Holding block headers: 0 bytes
  Used small blocks:     0 bytes
  Used ordinary blocks:  1484 KiB
  Free small blocks:     2096 bytes
  Free ordinary blocks:  100 KiB
  Ordinary blocks:       2
  Small blocks:          60
  Holding blocks:        0
(see system documentation for 'mallinfo' for meaning)
--- qmem libfrr ---
Buffer                        :          3      24                  72
Buffer data                   :          1    4120                4120
Host config                   :          3  (variably sized)        72
Command Tokens                :       3427      72              247160
Command Token Text            :       2555  (variably sized)     83720
Command Token Help            :       2555  (variably sized)     61720
Command Argument              :          2  (variably sized)        48
Command Argument Name         :        641  (variably sized)     15672
[...]
--- qmem Label Manager ---
--- qmem zebra ---
ZEBRA VRF                     :          1     912                 920
Route Entry                   :         11      80                 968
Static route                  :          1     192                 200
RIB destination               :          8      48                 448
RIB table info                :          4      16                  96
Nexthop tracking object       :          1     200                 200
Zebra Name Space              :          1     312                 312
--- qmem Table Manager ---

To understand system allocator statistics, refer to your system’s mallinfo(3) man page.

Below these statistics, statistics on individual memory allocation types in frr (so-called MTYPEs) is printed:

the first column of numbers is the current count of allocations made for the type (the number decreases when items are freed.)
the second column is the size of each item. This is only available if allocations on a type are always made with the same size.
the third column is the total amount of memory allocated for the particular type, including padding applied by malloc. This means that the number may be larger than the first column multiplied by the second. Overhead incurred by malloc’s bookkeeping is not included in this, and the column may be missing if system support is not available.

When executing this command from vtysh, each of the daemons’ memory usage is printed sequentially.

logmsg LEVEL MESSAGE¶: Send a message to all logging destinations that are enabled for messages of the given severity.

find COMMAND...¶

This command performs a simple substring search across all defined commands in all modes. As an example, suppose you’re in enable mode and can’t remember where the command to turn OSPF segment routing on is:

frr# find segment-routing on
  (ospf)  segment-routing on

The CLI mode is displayed next to each command. In this example, segment-routing on is under the router ospf mode.

Similarly, suppose you want a listing of all commands that contain “l2vpn”:

frr# find l2vpn
  (view)  show [ip] bgp l2vpn evpn [json]
  (view)  show [ip] bgp l2vpn evpn all <A.B.C.D|A.B.C.D/M> [json]
  (view)  show [ip] bgp l2vpn evpn all neighbors A.B.C.D advertised-routes [json]
  (view)  show [ip] bgp l2vpn evpn all neighbors A.B.C.D routes [json]
  (view)  show [ip] bgp l2vpn evpn all overlay
  ...

show thread cpu [r|w|t|e|x]¶: This command displays system run statistics for all the different event types. If no options is specified all different run types are displayed together. Additionally you can ask to look at (r)ead, (w)rite, (t)imer, (e)vent and e(x)ecute thread event types. If you have compiled with disable-cpu-time then this command will not show up.

show thread poll¶: This command displays FRR’s poll data. It allows a glimpse into how we are setting each individual fd for the poll command at that point in time.

Common Invocation Options¶

These options apply to all frr daemons.

-d, --daemon¶: Run in daemon mode.

-f, --config_file <file>¶: Set configuration file name.

-h, --help¶: Display this help and exit.

-i, --pid_file <file>¶

Upon startup the process identifier of the daemon is written to a file, typically in /var/run. This file can be used by the init system to implement commands such as .../init.d/zebra status, .../init.d/zebra restart or .../init.d/zebra stop.

The file name is an run-time option rather than a configure-time option so that multiple routing daemons can be run simultaneously. This is useful when using frr to implement a routing looking glass. One machine can be used to collect differing routing views from differing points in the network.

-A, --vty_addr <address>¶: Set the VTY local address to bind to. If set, the VTY socket will only be bound to this address.

-P, --vty_port <port>¶: Set the VTY TCP port number. If set to 0 then the TCP VTY sockets will not be opened.

-u <user>¶: Set the user and group to run as.

-N <namespace>¶: Set the namespace that the daemon will run in. A “/<namespace>” will be added to all files that use the statedir. If you have “/var/run/frr” as the default statedir then it will become “/var/run/frr/<namespace>”.

-v, --version¶: Print program version.

--command-log-always¶: Cause the daemon to always log commands entered to the specified log file. This also makes the no log commands command dissallowed. Enabling this is suggested if you have need to track what the operator is doing on this router.

--log <stdout|syslog|file:/path/to/log/file>¶: When initializing the daemon, setup the log to go to either stdout, syslog or to a file. These values will be displayed as part of a show run. Additionally they can be overridden at runtime if desired via the normal log commands.

--log-level <emergencies|alerts|critical|errors|warnings|notifications|informational|debugging>¶: When initializing the daemon, allow the specification of a default log level at startup from one of the specified levels.

--tcli¶: Enable the transactional CLI mode.

Loadable Module Support¶

FRR supports loading extension modules at startup. Loading, reloading or unloading modules at runtime is not supported (yet). To load a module, use the following command line option at daemon startup:

-M, --module <module:options>¶

Load the specified module, optionally passing options to it. If the module name contains a slash (/), it is assumed to be a full pathname to a file to be loaded. If it does not contain a slash, the /usr/lib/frr/modules directory is searched for a module of the given name; first with the daemon name prepended (e.g. zebra_mod for mod), then without the daemon name prepended.

This option is available on all daemons, though some daemons may not have any modules available to be loaded.

The SNMP Module¶

If SNMP is enabled during compile-time and installed as part of the package, the snmp module can be loaded for the Zebra, bgpd, ospfd, ospf6d and ripd daemons.

The module ignores any options passed to it. Refer to SNMP Support for information on its usage.

The FPM Module¶

If FPM is enabled during compile-time and installed as part of the package, the fpm module can be loaded for the zebra daemon. This provides the Forwarding Plane Manager (“FPM”) API.

The module expects its argument to be either Netlink or protobuf, specifying the encapsulation to use. Netlink is the default, and protobuf may not be available if the module was built without protobuf support. Refer to zebra FIB push interface for more information.

Virtual Terminal Interfaces¶

VTY – Virtual Terminal [aka TeletYpe] Interface is a command line interface (CLI) for user interaction with the routing daemon.

VTY Overview¶

VTY stands for Virtual TeletYpe interface. It means you can connect to the daemon via the telnet protocol.

To enable a VTY interface, you have to setup a VTY password. If there is no VTY password, one cannot connect to the VTY interface at all.

% telnet localhost 2601
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.

Hello, this is |PACKAGE_NAME| (version |PACKAGE_VERSION|)
|COPYRIGHT_STR|

User Access Verification

Password: XXXXX
Router> ?
  enable .  .  .  Turn on privileged commands
  exit   .  .  .  Exit current mode and down to previous mode
  help   .  .  .  Description of the interactive help system
  list   .  .  .  Print command list
  show   .  .  .  Show system inform

  wh. . .  Display who is on a vty
Router> enable
Password: XXXXX
Router# configure terminal
Router(config)# interface eth0
Router(config-if)# ip address 10.0.0.1/8
Router(config-if)# ^Z
Router#

VTY Modes¶

There are three basic VTY modes:

There are commands that may be restricted to specific VTY modes.

VTY View Mode¶

This mode is for read-only access to the CLI. One may exit the mode by leaving the system, or by entering enable mode.

VTY Enable Mode¶

This mode is for read-write access to the CLI. One may exit the mode by leaving the system, or by escaping to view mode.

VTY Other Modes¶

This page is for describing other modes.

VTY CLI Commands¶

Commands that you may use at the command-line are described in the following three subsubsections.

CLI Movement Commands¶

These commands are used for moving the CLI cursor. The C character means press the Control Key.

C-f / LEFT: Move forward one character.
C-b / RIGHT: Move backward one character.
M-f: Move forward one word.
M-b: Move backward one word.
C-a: Move to the beginning of the line.
C-e: Move to the end of the line.

CLI Editing Commands¶

These commands are used for editing text on a line. The C character means press the Control Key.

C-h / DEL: Delete the character before point.
C-d: Delete the character after point.
M-d: Forward kill word.
C-w: Backward kill word.
C-k: Kill to the end of the line.
C-u: Kill line from the beginning, erasing input.
C-t: Transpose character.

CLI Advanced Commands¶

There are several additional CLI commands for command line completions, insta-help, and VTY session management.

C-c: Interrupt current input and moves to the next line.
C-z: End current configuration session and move to top node.
C-n / DOWN: Move down to next line in the history buffer.
C-p / UP: Move up to previous line in the history buffer.
TAB: Use command line completion by typing TAB.
?: You can use command line help by typing help at the beginning of the line. Typing ? at any point in the line will show possible completions.

Pipe Actions¶

VTY supports optional modifiers at the end of commands that perform postprocessing on command output or modify the action of commands. These do not show up in the ? or TAB suggestion lists.

... | include REGEX

Filters the output of the preceding command, including only lines which match the POSIX Extended Regular Expression REGEX. Do not put the regex in quotes.

Examples:

frr# show ip bgp sum json | include remoteAs
      "remoteAs":0,
      "remoteAs":455,
      "remoteAs":99,

frr# show run | include neigh.*[0-9]{2}\.0\.[2-4]\.[0-9]*
 neighbor 10.0.2.106 remote-as 99
 neighbor 10.0.2.107 remote-as 99
 neighbor 10.0.2.108 remote-as 99
 neighbor 10.0.2.109 remote-as 99
 neighbor 10.0.2.110 remote-as 99
 neighbor 10.0.3.111 remote-as 111

VTY shell¶

vtysh provides a combined frontend to all FRR daemons in a single combined session. It is enabled by default at build time, but can be disabled through the --disable-vtysh option to the configure script.

vtysh has a configuration file, vtysh.conf. The location of that file cannot be changed from /etc/frr since it contains options controlling authentication behavior. This file will also not be written by configuration-save commands, it is intended to be updated manually by an administrator with an external editor.

Warning

This also means the hostname and banner motd commands (which both do have effect for vtysh) need to be manually updated in vtysh.conf.

Permissions and setup requirements¶

vtysh connects to running daemons through Unix sockets located in /var/run/frr. Running vtysh thus requires access to that directory, plus membership in the frrvty group (which is the group that the daemons will change ownership of their sockets to).

To restrict access to FRR configuration, make sure no unauthorized users are members of the frrvty group.

Warning

VTYSH implements a CLI option -u, --user that disallows entering the characters “en” on the command line, which ideally restricts access to configuration commands. However, VTYSH was never designed to be a privilege broker and is not built using secure coding practices. No guarantees of security are provided for this option and under no circumstances should this option be used to provide any semblance of security or read-only access to FRR.

PAM support (experimental)¶

vtysh has working (but rather useless) PAM support. It will perform an “authenticate” PAM call using frr as service name. No other (accounting, session, password change) calls will be performed by vtysh.

Users using vtysh still need to have appropriate access to the daemons’ VTY sockets, usually by being member of the frrvty group. If they have this membership, PAM support is useless since they can connect to daemons and issue commands using some other tool. Alternatively, the vtysh binary could be made SGID (set group ID) to the frrvty group.

Warning

No security guarantees are made for this configuration.

username USERNAME nopassword¶: If PAM support is enabled at build-time, this command allows disabling the use of PAM on a per-user basis. If vtysh finds that an user is trying to use vtysh and a “nopassword” entry is found, no calls to PAM will be made at all.

Integrated configuration mode¶

Integrated configuration mode uses a single configuration file, frr.conf, for all daemons. This replaces the individual files like zebra.conf or bgpd.conf.

frr.conf is located in /etc/frr. All daemons check for the existence of this file at startup, and if it exists will not load their individual configuration files. Instead, vtysh -b must be invoked to process frr.conf and apply its settings to the individual daemons.

Warning

vtysh -b must also be executed after restarting any daemon.

Configuration saving, file ownership and permissions¶

The frr.conf file is not written by any of the daemons; instead vtysh contains the necessary logic to collect configuration from all of the daemons, combine it and write it out.

Warning

Daemons must be running for vtysh to be able to collect their configuration. Any configuration from non-running daemons is permanently lost after doing a configuration save.

Since the vtysh command may be running as ordinary user on the system, configuration writes will be tried through watchfrr, using the write integrated command internally. Since watchfrr is running as superuser, vtysh is able to ensure correct ownership and permissions on frr.conf.

If watchfrr is not running or the configuration write fails, vtysh will attempt to directly write to the file. This is likely to fail if running as unprivileged user; alternatively it may leave the file with incorrect owner or permissions.

Writing the configuration can be triggered directly by invoking vtysh -w. This may be useful for scripting. Note this command should be run as either the superuser or the FRR user.

We recommend you do not mix the use of the two types of files. Further, it is better not to use the integrated frr.conf file, as any syntax error in it can lead to /all/ of your daemons being unable to start up. Per daemon files are more robust as impact of errors in configuration are limited to the daemon in whose file the error is made.

service integrated-vtysh-config¶

no service integrated-vtysh-config¶

Control whether integrated frr.conf file is written when ‘write file’ is issued.

These commands need to be placed in vtysh.conf to have any effect. Note that since vtysh.conf is not written by FRR itself, they therefore need to be manually placed in that file.

This command has 3 states:

service integrated-vtysh-config: vtysh will always write frr.conf.
no service integrated-vtysh-config: vtysh will never write frr.conf; instead it will ask daemons to write their individual configuration files.
Neither option present (default): vtysh will check whether frr.conf exists. If it does, configuration writes will update that file. Otherwise, writes are performed through the individual daemons.

This command is primarily intended for packaging/distribution purposes, to preset one of the two operating modes and ensure consistent operation across installations.

write integrated¶: Unconditionally (regardless of service integrated-vtysh-config setting) write out integrated frr.conf file through watchfrr. If watchfrr is not running, this command is unavailable.

Warning

Configuration changes made while some daemon is not running will be invisible to that daemon. The daemon will start up with its saved configuration (either in its individual configuration file, or in frr.conf). This is particularly troublesome for route-maps and prefix lists, which would otherwise be synchronized between daemons.

Filtering¶

FRR provides many very flexible filtering features. Filtering is used for both input and output of the routing information. Once filtering is defined, it can be applied in any direction.

IP Access List¶

access-list NAME [seq (1-4294967295)] permit IPV4-NETWORK¶

access-list NAME [seq (1-4294967295)] deny IPV4-NETWORK¶

seq: seq number can be set either automatically or manually. In the case that sequential numbers are set manually, the user may pick any number less than 4294967295. In the case that sequential number are set automatically, the sequential number will increase by a unit of five (5) per list. If a list with no specified sequential number is created after a list with a specified sequential number, the list will automatically pick the next multiple of five (5) as the list number. For example, if a list with number 2 already exists and a new list with no specified number is created, the next list will be numbered 5. If lists 2 and 7 already exist and a new list with no specified number is created, the new list will be numbered 10.

Basic filtering is done by access-list as shown in the following example.

access-list filter deny 10.0.0.0/9
access-list filter permit 10.0.0.0/8
access-list filter seq 13 permit 10.0.0.0/7

IP Prefix List¶

ip prefix-list provides the most powerful prefix based filtering mechanism. In addition to access-list functionality, ip prefix-list has prefix length range specification and sequential number specification. You can add or delete prefix based filters to arbitrary points of prefix-list using sequential number specification.

If no ip prefix-list is specified, it acts as permit. If ip prefix-list is defined, and no match is found, default deny is applied.

ip prefix-list NAME (permit|deny) PREFIX [le LEN] [ge LEN]¶

ip prefix-list NAME seq NUMBER (permit|deny) PREFIX [le LEN] [ge LEN]¶

You can create ip prefix-list using above commands.

seq: seq number can be set either automatically or manually. In the case that sequential numbers are set manually, the user may pick any number less than 4294967295. In the case that sequential number are set automatically, the sequential number will increase by a unit of five (5) per list. If a list with no specified sequential number is created after a list with a specified sequential number, the list will automatically pick the next multiple of five (5) as the list number. For example, if a list with number 2 already exists and a new list with no specified number is created, the next list will be numbered 5. If lists 2 and 7 already exist and a new list with no specified number is created, the new list will be numbered 10.
le: Specifies prefix length. The prefix list will be applied if the prefix length is less than or equal to the le prefix length.
ge: Specifies prefix length. The prefix list will be applied if the prefix length is greater than or equal to the ge prefix length.

Less than or equal to prefix numbers and greater than or equal to prefix numbers can be used together. The order of the le and ge commands does not matter.

If a prefix list with a different sequential number but with the exact same rules as a previous list is created, an error will result. However, in the case that the sequential number and the rules are exactly similar, no error will result.

If a list with the same sequential number as a previous list is created, the new list will overwrite the old list.

Matching of IP Prefix is performed from the smaller sequential number to the larger. The matching will stop once any rule has been applied.

In the case of no le or ge command, the prefix length must match exactly the length specified in the prefix list.

no ip prefix-list NAME¶

ip prefix-list description¶

ip prefix-list NAME description DESC¶: Descriptions may be added to prefix lists. This command adds a description to the prefix list.

no ip prefix-list NAME description [DESC]¶: Deletes the description from a prefix list. It is possible to use the command without the full description.

ip prefix-list sequential number control¶

ip prefix-list sequence-number¶: With this command, the IP prefix list sequential number is displayed. This is the default behavior.

no ip prefix-list sequence-number¶: With this command, the IP prefix list sequential number is not displayed.

Showing ip prefix-list¶

show ip prefix-list¶: Display all IP prefix lists.

show ip prefix-list NAME¶: Show IP prefix list can be used with a prefix list name.

show ip prefix-list NAME seq NUM¶: Show IP prefix list can be used with a prefix list name and sequential number.

show ip prefix-list NAME A.B.C.D/M¶: If the command longer is used, all prefix lists with prefix lengths equal to or longer than the specified length will be displayed. If the command first match is used, the first prefix length match will be displayed.

show ip prefix-list NAME A.B.C.D/M longer¶

show ip prefix-list NAME A.B.C.D/M first-match¶

show ip prefix-list summary¶

show ip prefix-list summary NAME¶

show ip prefix-list detail¶

show ip prefix-list detail NAME¶

Clear counter of ip prefix-list¶

clear ip prefix-list [NAME [A.B.C.D/M]]¶: Clears the counters of all IP prefix lists. Clear IP Prefix List can be used with a specified NAME or NAME and prefix.

Route Maps¶

Route maps provide a means to both filter and/or apply actions to route, hence allowing policy to be applied to routes.

For a route reflector to apply a route-map to reflected routes, be sure to include bgp route-reflector allow-outbound-policy in router bgp mode.

Route maps are an ordered list of route map entries. Each entry may specify up to four distinct sets of clauses:

Matching Conditions

A route-map entry may, optionally, specify one or more conditions which must be matched if the entry is to be considered further, as governed by the Match Policy. If a route-map entry does not explicitly specify any matching conditions, then it always matches.

Set Actions

A route-map entry may, optionally, specify one or more Set Actions to set or modify attributes of the route.

Matching Policy

This specifies the policy implied if the Matching Conditions are met or not met, and which actions of the route-map are to be taken, if any. The two possibilities are:

permit: If the entry matches, then carry out the Set Actions. Then finish processing the route-map, permitting the route, unless an Exit Policy action indicates otherwise.
deny: If the entry matches, then finish processing the route-map and deny the route (return deny).

The Matching Policy is specified as part of the command which defines the ordered entry in the route-map. See below.

Call Action

Call to another route-map, after any Set Actions have been carried out. If the route-map called returns deny then processing of the route-map finishes and the route is denied, regardless of the Matching Policy or the Exit Policy. If the called route-map returns permit, then Matching Policy and Exit Policy govern further behaviour, as normal.

Exit Policy

An entry may, optionally, specify an alternative Exit Policy to take if the entry matched, rather than the normal policy of exiting the route-map and permitting the route. The two possibilities are:

next: Continue on with processing of the route-map entries.
goto N: Jump ahead to the first route-map entry whose order in the route-map is >= N. Jumping to a previous entry is not permitted.

The default action of a route-map, if no entries match, is to deny. I.e. a route-map essentially has as its last entry an empty deny entry, which matches all routes. To change this behaviour, one must specify an empty permit entry as the last entry in the route-map.

To summarise the above:

	Match	No Match
Permit	action	cont
Deny	deny	cont

action

Apply set statements
If call is present, call given route-map. If that returns a deny, finish processing and return deny.
If Exit Policy is next, goto next route-map entry
If Exit Policy is goto, goto first entry whose order in the list is >= the given order.
Finish processing the route-map and permit the route.

deny

The route is denied by the route-map (return deny).

cont

goto next route-map entry

show route-map [WORD]¶: Display data about each daemons knowledge of individual route-maps. If WORD is supplied narrow choice to that particular route-map.

clear route-map counter [WORD]¶: Clear counters that are being stored about the route-map utilization so that subsuquent show commands will indicate since the last clear. If WORD is specified clear just that particular route-map’s counters.

Route Map Command¶

route-map ROUTE-MAP-NAME (permit|deny) ORDER¶: Configure the order’th entry in route-map-name with Match Policy of either permit or deny.

Route Map Match Command¶

match ip address ACCESS_LIST¶: Matches the specified access_list

match ip address prefix-list PREFIX_LIST¶: Matches the specified PREFIX_LIST

match ip address prefix-len 0-32¶: Matches the specified prefix-len. This is a Zebra specific command.

match ipv6 address ACCESS_LIST¶: Matches the specified access_list

match ipv6 address prefix-list PREFIX_LIST¶: Matches the specified PREFIX_LIST

match ipv6 address prefix-len 0-128¶: Matches the specified prefix-len. This is a Zebra specific command.

match ip next-hop IPV4_ADDR¶: Matches the specified ipv4_addr.

match as-path AS_PATH¶: Matches the specified as_path.

match metric METRIC¶: Matches the specified metric.

match tag TAG¶: Matches the specified tag value associated with the route. This tag value can be in the range of (1-4294967295).

match local-preference METRIC¶: Matches the specified local-preference.

match community COMMUNITY_LIST¶: Matches the specified community_list

match peer IPV4_ADDR¶: This is a BGP specific match command. Matches the peer ip address if the neighbor was specified in this manner.

match peer IPV6_ADDR¶: This is a BGP specific match command. Matches the peer ipv6 address if the neighbor was specified in this manner.

match peer INTERFACE_NAME¶: This is a BGP specific match command. Matches the peer interface name specified if the neighbor was specified in this manner.

match source-protocol PROTOCOL_NAME¶: This is a ZEBRA specific match command. Matches the originating protocol specified.

match source-instance NUMBER¶: This is a ZEBRA specific match command. The number is a range from (0-255). Matches the originating protocols instance specified.

Route Map Set Command¶

set tag TAG¶: Set a tag on the matched route. This tag value can be from (1-4294967295). Additionally if you have compiled with the --enable-realms configure option. Tag values from (1-255) are sent to the Linux kernel as a realm value. Then route policy can be applied. See the tc man page.

set ip next-hop IPV4_ADDRESS¶: Set the BGP nexthop address to the specified IPV4_ADDRESS. For both incoming and outgoing route-maps.

set ip next-hop peer-address¶: Set the BGP nexthop address to the address of the peer. For an incoming route-map this means the ip address of our peer is used. For an outgoing route-map this means the ip address of our self is used to establish the peering with our neighbor.

set ip next-hop unchanged¶: Set the route-map as unchanged. Pass the route-map through without changing it’s value.

set ipv6 next-hop peer-address¶: Set the BGP nexthop address to the address of the peer. For an incoming route-map this means the ipv6 address of our peer is used. For an outgoing route-map this means the ip address of our self is used to establish the peering with our neighbor.

set ipv6 next-hop prefer-global¶: For Incoming and Import Route-maps if we receive a v6 global and v6 LL address for the route, then prefer to use the global address as the nexthop.

set ipv6 next-hop global IPV6_ADDRESS¶: Set the next-hop to the specified IPV6_ADDRESS for both incoming and outgoing route-maps.

set local-preference LOCAL_PREF¶: Set the BGP local preference to local_pref.

[no] set distance DISTANCE¶: Set the Administrative distance to DISTANCE to use for the route. This is only locally significant and will not be dispersed to peers.

set weight WEIGHT¶: Set the route’s weight.

set metric METRIC¶: Set the BGP attribute MED.

set as-path prepend AS_PATH¶: Set the BGP AS path to prepend.

set community COMMUNITY¶: Set the BGP community attribute.

set ipv6 next-hop local IPV6_ADDRESS¶: Set the BGP-4+ link local IPv6 nexthop address.

set origin ORIGIN <egp|igp|incomplete>¶: Set BGP route origin.

set table (1-4294967295)¶: Set the BGP table to a given table identifier

Route Map Call Command¶

call NAME¶: Call route-map name. If it returns deny, deny the route and finish processing the route-map.

Route Map Exit Action Command¶

on-match next¶

continue¶: Proceed on to the next entry in the route-map.

on-match goto N¶

continue N¶: Proceed processing the route-map at the first entry whose order is >= N

Route Map Examples¶

A simple example of a route-map:

route-map test permit 10
 match ip address 10
 set local-preference 200

This means that if a route matches ip access-list number 10 it’s local-preference value is set to 200.

See Miscellaneous Configuration Examples for examples of more sophisticated usage of route-maps, including of the call action.

IPv6 Support¶

FRR fully supports IPv6 routing. As described so far, FRR supports RIPng, OSPFv3, and BGP-4+. You can give IPv6 addresses to an interface and configure static IPv6 routing information. FRR IPv6 also provides automatic address configuration via a feature called address auto configuration. To do it, the router must send router advertisement messages to the all nodes that exist on the network.

Previous versions of FRR could be built without IPv6 support. This is no longer possible.

Router Advertisement¶

no ipv6 nd suppress-ra¶: Send router advertisement messages.

ipv6 nd suppress-ra¶: Don’t send router advertisement messages.

ipv6 nd prefix ipv6prefix [valid-lifetime] [preferred-lifetime] [off-link] [no-autoconfig] [router-address]¶

Configuring the IPv6 prefix to include in router advertisements. Several prefix specific optional parameters and flags may follow:

valid-lifetime: the length of time in seconds during what the prefix is valid for the purpose of on-link determination. Value infinite represents infinity (i.e. a value of all one bits (0xffffffff)). Range: (0-4294967295) Default: 2592000
preferred-lifetime: the length of time in seconds during what addresses generated from the prefix remain preferred. Value infinite represents infinity. Range: (0-4294967295) Default: 604800
off-link: indicates that advertisement makes no statement about on-link or off-link properties of the prefix. Default: not set, i.e. this prefix can be used for on-link determination.
no-autoconfig: indicates to hosts on the local link that the specified prefix cannot be used for IPv6 autoconfiguration.

Default: not set, i.e. prefix can be used for autoconfiguration.
router-address: indicates to hosts on the local link that the specified prefix contains a complete IP address by setting R flag.

Default: not set, i.e. hosts do not assume a complete IP address is placed.

[no] ipv6 nd ra-interval [(1-1800)]¶: The maximum time allowed between sending unsolicited multicast router advertisements from the interface, in seconds. Default: 600

[no] ipv6 nd ra-interval [msec (70-1800000)]¶: The maximum time allowed between sending unsolicited multicast router advertisements from the interface, in milliseconds. Default: 600000

[no] ipv6 nd ra-fast-retrans¶: RFC4861 states that consecutive RA packets should be sent no more frequently than three seconds apart. FRR by default allows faster transmissions of RA packets in order to speed convergence and neighbor establishment, particularly for unnumbered peering. By turning off ipv6 nd ra-fast-retrans, the implementation is compliant with the RFC at the cost of slower convergence and neighbor establishment. Default: enabled

[no] ipv6 nd ra-lifetime [(0-9000)]¶: The value to be placed in the Router Lifetime field of router advertisements sent from the interface, in seconds. Indicates the usefulness of the router as a default router on this interface. Setting the value to zero indicates that the router should not be considered a default router on this interface. Must be either zero or between value specified with ipv6 nd ra-interval (or default) and 9000 seconds. Default: 1800

[no] ipv6 nd reachable-time [(1-3600000)]¶: The value to be placed in the Reachable Time field in the Router Advertisement messages sent by the router, in milliseconds. The configured time enables the router to detect unavailable neighbors. The value zero means unspecified (by this router). Default: 0

[no] ipv6 nd managed-config-flag¶: Set/unset flag in IPv6 router advertisements which indicates to hosts that they should use managed (stateful) protocol for addresses autoconfiguration in addition to any addresses autoconfigured using stateless address autoconfiguration. Default: not set

[no] ipv6 nd other-config-flag¶: Set/unset flag in IPv6 router advertisements which indicates to hosts that they should use administered (stateful) protocol to obtain autoconfiguration information other than addresses. Default: not set

[no] ipv6 nd home-agent-config-flag¶: Set/unset flag in IPv6 router advertisements which indicates to hosts that the router acts as a Home Agent and includes a Home Agent Option. Default: not set

[no] ipv6 nd home-agent-preference [(0-65535)]¶: The value to be placed in Home Agent Option, when Home Agent config flag is set, which indicates to hosts Home Agent preference. The default value of 0 stands for the lowest preference possible. Default: 0

[no] ipv6 nd home-agent-lifetime [(0-65520)]¶

The value to be placed in Home Agent Option, when Home Agent config flag is set, which indicates to hosts Home Agent Lifetime. The default value of 0 means to place the current Router Lifetime value.

Default: 0

[no] ipv6 nd adv-interval-option¶: Include an Advertisement Interval option which indicates to hosts the maximum time, in milliseconds, between successive unsolicited Router Advertisements. Default: not set

[no] ipv6 nd router-preference [(high|medium|low)]¶: Set default router preference in IPv6 router advertisements per RFC4191. Default: medium

[no] ipv6 nd mtu [(1-65535)]¶

Include an MTU (type 5) option in each RA packet to assist the attached hosts in proper interface configuration. The announced value is not verified to be consistent with router interface MTU.

Default: don’t advertise any MTU option.

[no] ipv6 nd rdnss ipv6address [lifetime]¶

Recursive DNS server address to advertise using the RDNSS (type 25) option described in RFC8106. Can be specified more than once to advertise multiple addresses. Note that hosts may choose to limit the number of RDNSS addresses to track.

Optional parameter:

lifetime: the maximum time in seconds over which the specified address may be used for domain name resolution. Value infinite represents infinity (i.e. a value of all one bits (0xffffffff)). A value of 0 indicates that the address must no longer be used. Range: (0-4294967295) Default: 3 * ra-interval

Default: do not emit RDNSS option

[no] ipv6 nd dnssl domain-name-suffix [lifetime]¶

Advertise DNS search list using the DNSSL (type 31) option described in RFC8106. Specify more than once to advertise multiple domain name suffixes. Host implementations may limit the number of honored search list entries.

Optional parameter:

lifetime: the maximum time in seconds over which the specified domain suffix may be used in the course of name resolution. Value infinite represents infinity (i.e. a value of all one bits (0xffffffff)). A value of 0 indicates that the name suffix must no longer be used. Range: (0-4294967295) Default: 3 * ra-interval

Default: do not emit DNSSL option

Router Advertisement Configuration Example¶

A small example:

interface eth0
 no ipv6 nd suppress-ra
 ipv6 nd prefix 2001:0DB8:5009::/64

See also

RFC 2462 (IPv6 Stateless Address Autoconfiguration)
RFC 4861 (Neighbor Discovery for IP Version 6 (IPv6))
RFC 6275 (Mobility Support in IPv6)
RFC 4191 (Default Router Preferences and More-Specific Routes)
RFC 8106 (IPv6 Router Advertisement Options for DNS Configuration)

Kernel Interface¶

There are several different methods for reading kernel routing table information, updating kernel routing tables, and for looking up interfaces.

ioctl

This method is a very traditional way for reading or writing kernel information. ioctl can be used for looking up interfaces and for modifying interface addresses, flags, mtu settings and other types of information. Also, ioctl can insert and delete kernel routing table entries. It will soon be available on almost any platform which zebra supports, but it is a little bit ugly thus far, so if a better method is supported by the kernel, zebra will use that.
sysctl

This is a program that can lookup kernel information using MIB (Management Information Base) syntax. Normally, it only provides a way of getting information from the kernel. So one would usually want to change kernel information using another method such as ioctl.
proc filesystem

This is a special filesystem mount that provides an easy way of getting kernel information.
routing socket / Netlink

On recent Linux kernels (2.0.x and 2.2.x), there is a kernel/user communication support called Netlink. It makes asynchronous communication between kernel and FRR possible, similar to a routing socket on BSD systems.

Before you use this feature, be sure to select (in kernel configuration) the kernel/Netlink support option ‘Kernel/User network link driver’ and ‘Routing messages’.

Today, the /dev/route special device file is obsolete. Netlink communication is done by reading/writing over Netlink socket.

After the kernel configuration, please reconfigure and rebuild FRR. You can use Netlink as a dynamic routing update channel between FRR and the kernel.

SNMP Support¶

SNMP is a widely implemented feature for collecting network information from router and/or host. FRR itself does not support SNMP agent (server daemon) functionality but is able to connect to a SNMP agent using the the AgentX protocol (RFC 2741) and make the routing protocol MIBs available through it.

Note that SNMP Support needs to be enabled at compile-time and loaded as module on daemon startup. Refer to Loadable Module Support on the latter.

Getting and installing an SNMP agent¶

The supported SNMP agent is AgentX. We recommend to use the latest version of net-snmp which was formerly known as ucd-snmp. It is free and open software and available at http://www.net-snmp.org/ and as binary package for most Linux distributions.

AgentX configuration¶

To enable AgentX protocol support, FRR must have been build with the --enable-snmp or –enable-snmp=agentx option. Both the master SNMP agent (snmpd) and each of the FRR daemons must be configured. In /etc/snmp/snmpd.conf, the master agentx directive should be added. In each of the FRR daemons, agentx command will enable AgentX support.

/etc/snmp/zebra.conf:

#
# example access restrictions setup
#
com2sec readonly default public
group MyROGroup v1 readonly
view all included .1 80
access MyROGroup "" any noauth exact all none none
#
# enable master agent for AgentX subagents
#
master agentx

/etc/frr/ospfd.conf:

! ... the rest of ospfd.conf has been omitted for clarity ...
!
agentx
!

Upon successful connection, you should get something like this in the log of each FRR daemons:

2012/05/25 11:39:08 ZEBRA: snmp[info]: NET-SNMP version 5.4.3 AgentX subagent connected

Then, you can use the following command to check everything works as expected:

# snmpwalk -c public -v1 localhost .1.3.6.1.2.1.14.1.1
OSPF-MIB::ospfRouterId.0 = IpAddress: 192.168.42.109
[...]

The AgentX protocol can be transported over a Unix socket or using TCP or UDP. It usually defaults to a Unix socket and depends on how NetSNMP was built. If need to configure FRR to use another transport, you can configure it through /etc/snmp/frr.conf:

[snmpd]
# Use a remote master agent
agentXSocket tcp:192.168.15.12:705

Here is the syntax for using AgentX:

agentx¶

no agentx¶

Handling SNMP Traps¶

To handle snmp traps make sure your snmp setup of frr works correctly as described in the frr documentation in SNMP Support.

The BGP4 mib will send traps on peer up/down events. These should be visible in your snmp logs with a message similar to:

snmpd[13733]: Got trap from peer on fd 14

To react on these traps they should be handled by a trapsink. Configure your trapsink by adding the following lines to /etc/snmpd/snmpd.conf:

# send traps to the snmptrapd on localhost
trapsink localhost

This will send all traps to an snmptrapd running on localhost. You can of course also use a dedicated management station to catch traps. Configure the snmptrapd daemon by adding the following line to /etc/snmpd/snmptrapd.conf:

traphandle .1.3.6.1.4.1.3317.1.2.2 /etc/snmp/snmptrap_handle.sh

This will use the bash script /etc/snmp/snmptrap_handle.sh to handle the BGP4 traps. To add traps for other protocol daemons, lookup their appropriate OID from their mib. (For additional information about which traps are supported by your mib, lookup the mib on http://www.oidview.com/mibs/detail.html).

Make sure snmptrapd is started.

The snmptrap_handle.sh script I personally use for handling BGP4 traps is below. You can of course do all sorts of things when handling traps, like sound a siren, have your display flash, etc., be creative ;).

#!/bin/bash

# routers name
ROUTER=`hostname -s`

#email address use to sent out notification
EMAILADDR="john@doe.com"
#email address used (allongside above) where warnings should be sent
EMAILADDR_WARN="sms-john@doe.com"

# type of notification
TYPE="Notice"

# local snmp community for getting AS belonging to peer
COMMUNITY="<community>"

# if a peer address is in $WARN_PEERS a warning should be sent
WARN_PEERS="192.0.2.1"

# get stdin
INPUT=`cat -`

# get some vars from stdin
uptime=`echo $INPUT | cut -d' ' -f5`
peer=`echo $INPUT | cut -d' ' -f8 | sed -e 's/SNMPv2-SMI::mib-2.15.3.1.14.//g'`
peerstate=`echo $INPUT | cut -d' ' -f13`
errorcode=`echo $INPUT | cut -d' ' -f9 | sed -e 's/\\"//g'`
suberrorcode=`echo $INPUT | cut -d' ' -f10 | sed -e 's/\\"//g'`
remoteas=`snmpget -v2c -c $COMMUNITY localhost SNMPv2-SMI::mib-2.15.3.1.9.$peer | cut -d' ' -f4`

WHOISINFO=`whois -h whois.ripe.net " -r AS$remoteas" | egrep '(as-name|descr)'`
asname=`echo "$WHOISINFO" | grep "^as-name:" | sed -e 's/^as-name://g' -e 's/  //g' -e 's/^ //g' | uniq`
asdescr=`echo "$WHOISINFO" | grep "^descr:" | sed -e 's/^descr://g' -e 's/  //g' -e 's/^ //g' | uniq`

# if peer address is in $WARN_PEER, the email should also
# be sent to $EMAILADDR_WARN
for ip in $WARN_PEERS; do
if [ "x$ip" == "x$peer" ]; then
EMAILADDR="$EMAILADDR,$EMAILADDR_WARN"
TYPE="WARNING"
break
fi
done

# convert peer state
case "$peerstate" in
1) peerstate="Idle" ;;
2) peerstate="Connect" ;;
3) peerstate="Active" ;;
4) peerstate="Opensent" ;;
5) peerstate="Openconfirm" ;;
6) peerstate="Established" ;;
*) peerstate="Unknown" ;;
esac

# get textual messages for errors
case "$errorcode" in
00)
error="No error"
suberror=""
;;
01)
error="Message Header Error"
case "$suberrorcode" in
01) suberror="Connection Not Synchronized" ;;
02) suberror="Bad Message Length" ;;
03) suberror="Bad Message Type" ;;
*) suberror="Unknown" ;;
esac
;;
02)
error="OPEN Message Error"
case "$suberrorcode" in
01) suberror="Unsupported Version Number" ;;
02) suberror="Bad Peer AS" ;;
03) suberror="Bad BGP Identifier" ;;
04) suberror="Unsupported Optional Parameter" ;;
05) suberror="Authentication Failure" ;;
06) suberror="Unacceptable Hold Time" ;;
*) suberror="Unknown" ;;
esac
;;
03)
error="UPDATE Message Error"
case "$suberrorcode" in
01) suberror="Malformed Attribute List" ;;
02) suberror="Unrecognized Well-known Attribute" ;;
03) suberror="Missing Well-known Attribute" ;;
04) suberror="Attribute Flags Error" ;;
05) suberror="Attribute Length Error" ;;
06) suberror="Invalid ORIGIN Attribute" ;;
07) suberror="AS Routing Loop" ;;
08) suberror="Invalid NEXT_HOP Attribute" ;;
09) suberror="Optional Attribute Error" ;;
10) suberror="Invalid Network Field" ;;
11) suberror="Malformed AS_PATH" ;;
*) suberror="Unknown" ;;
esac
;;
04)
error="Hold Timer Expired"
suberror=""
;;
05)
error="Finite State Machine Error"
suberror=""
;;
06)
error="Cease"
case "$suberrorcode" in
01) suberror="Maximum Number of Prefixes Reached" ;;
02) suberror="Administratively Shutdown" ;;
03) suberror="Peer Unconfigured" ;;
04) suberror="Administratively Reset" ;;
05) suberror="Connection Rejected" ;;
06) suberror="Other Configuration Change" ;;
07) suberror="Connection collision resolution" ;;
08) suberror="Out of Resource" ;;
09) suberror="MAX" ;;
*) suberror="Unknown" ;;
esac
;;
*)
error="Unknown"
suberror=""
;;
esac

# create textual message from errorcodes
if [ "x$suberror" == "x" ]; then
NOTIFY="$errorcode ($error)"
else
NOTIFY="$errorcode/$suberrorcode ($error/$suberror)"
fi

# form a decent subject
SUBJECT="$TYPE: $ROUTER [bgp] $peer is $peerstate: $NOTIFY"
# create the email body
MAIL=`cat << EOF
BGP notification on router $ROUTER.

Peer: $peer
AS: $remoteas
New state: $peerstate
Notification: $NOTIFY

Info:
$asname
$asdescr

Snmpd uptime: $uptime
EOF`

# mail the notification
echo "$MAIL" | mail -s "$SUBJECT" $EMAILADDR

Protocols¶

Zebra¶

zebra is an IP routing manager. It provides kernel routing table updates, interface lookups, and redistribution of routes between different routing protocols.

Invoking zebra¶

Besides the common invocation options (Common Invocation Options), the zebra specific invocation options are listed below.

-b, --batch¶: Runs in batch mode. zebra parses configuration file and terminates immediately.

-K TIME, --graceful_restart TIME¶: If this option is specified, the graceful restart time is TIME seconds. Zebra, when started, will read in routes. Those routes that Zebra identifies that it was the originator of will be swept in TIME seconds. If no time is specified then we will sweep those routes immediately.

-r, --retain¶: When program terminates, do not flush routes installed by zebra from the kernel.

-e X, --ecmp X¶: Run zebra with a limited ecmp ability compared to what it is compiled to. If you are running zebra on hardware limited functionality you can force zebra to limit the maximum ecmp allowed to X. This number is bounded by what you compiled FRR with as the maximum number.

-n, --vrfwnetns¶: When Zebra starts with this option, the VRF backend is based on Linux network namespaces. That implies that all network namespaces discovered by ZEBRA will create an associated VRF. The other daemons will operate on the VRF VRF defined by Zebra, as usual.

See also

Administrative Distance

-o, --vrfdefaultname¶: When Zebra starts with this option, the default VRF name is changed to the parameter.

See also

Administrative Distance

-z <path_to_socket>, --socket <path_to_socket>¶: If this option is supplied on the cli, the path to the zebra control socket(zapi), is used. This option overrides a -N <namespace> option if handed to it on the cli.

--v6-rr-semantics¶: The linux kernel is receiving the ability to use the same route replacement semantics for v6 that v4 uses. If you are using a kernel that supports this functionality then run Zebra with this option and we will use Route Replace Semantics instead of delete than add.

Configuration Addresses behaviour¶

At startup, Zebra will first discover the underlying networking objects from the operating system. This includes interfaces, addresses of interfaces, static routes, etc. Then, it will read the configuration file, including its own interface addresses, static routes, etc. All this information comprises the operational context from Zebra. But configuration context from Zebra will remain the same as the one from zebra.conf config file. As an example, executing the following show running-config will reflect what was in zebra.conf. In a similar way, networking objects that are configured outside of the Zebra like iproute2 will not impact the configuration context from Zebra. This behaviour permits you to continue saving your own config file, and decide what is really to be pushed on the config file, and what is dependent on the underlying system. Note that inversely, from Zebra, you will not be able to delete networking objects that were previously configured outside of Zebra.

Interface Commands¶

Standard Commands¶

interface IFNAME¶

interface IFNAME vrf VRF¶

shutdown¶

no shutdown¶: Up or down the current interface.

ip address ADDRESS/PREFIX¶

ipv6 address ADDRESS/PREFIX¶

no ip address ADDRESS/PREFIX¶

no ipv6 address ADDRESS/PREFIX¶: Set the IPv4 or IPv6 address/prefix for the interface.

ip address LOCAL-ADDR peer PEER-ADDR/PREFIX¶

no ip address LOCAL-ADDR peer PEER-ADDR/PREFIX¶

Configure an IPv4 Point-to-Point address on the interface. (The concept of PtP addressing does not exist for IPv6.)

local-addr has no subnet mask since the local side in PtP addressing is always a single (/32) address. peer-addr/prefix can be an arbitrary subnet behind the other end of the link (or even on the link in Point-to-Multipoint setups), though generally /32s are used.

description DESCRIPTION ...¶: Set description for the interface.

multicast¶

no multicast¶: Enable or disables multicast flag for the interface.

bandwidth (1-10000000)¶

no bandwidth (1-10000000)¶: Set bandwidth value of the interface in kilobits/sec. This is for calculating OSPF cost. This command does not affect the actual device configuration.

link-detect¶

no link-detect¶

Enable/disable link-detect on platforms which support this. Currently only Linux and Solaris, and only where network interface drivers support reporting link-state via the IFF_RUNNING flag.

In FRR, link-detect is on by default.

Link Parameters Commands¶

Note

At this time, FRR offers partial support for some of the routing protocol extensions that can be used with MPLS-TE. FRR does not support a complete RSVP-TE solution currently.

link-params¶

no link-param¶

Enter into the link parameters sub node. At least ‘enable’ must be set to activate the link parameters, and consequently routing information that could be used as part of Traffic Engineering on this interface. MPLS-TE must be enable at the OSPF (Traffic Engineering) or ISIS (Traffic Engineering) router level in complement to this. Disable link parameters for this interface.

Under link parameter statement, the following commands set the different TE values:

link-params [enable]¶: Enable link parameters for this interface.

link-params [metric (0-4294967295)]¶

link-params max-bw BANDWIDTH¶

link-params max-rsv-bw BANDWIDTH¶

link-params unrsv-bw (0-7) BANDWIDTH¶

link-params admin-grp BANDWIDTH¶

These commands specifies the Traffic Engineering parameters of the interface in conformity to RFC3630 (OSPF) or RFC5305 (ISIS). There are respectively the TE Metric (different from the OSPF or ISIS metric), Maximum Bandwidth (interface speed by default), Maximum Reservable Bandwidth, Unreserved Bandwidth for each 0-7 priority and Admin Group (ISIS) or Resource Class/Color (OSPF).

Note that BANDIWDTH is specified in IEEE floating point format and express in Bytes/second.

link-param delay (0-16777215) [min (0-16777215) | max (0-16777215)]¶

link-param delay-variation (0-16777215)¶

link-param packet-loss PERCENTAGE¶

link-param res-bw BANDWIDTH¶

link-param ava-bw BANDWIDTH¶

link-param use-bw BANDWIDTH¶

These command specifies additional Traffic Engineering parameters of the interface in conformity to draft-ietf-ospf-te-metrics-extension-05.txt and draft-ietf-isis-te-metrics-extension-03.txt. There are respectively the delay, jitter, loss, available bandwidth, reservable bandwidth and utilized bandwidth.

Note that BANDWIDTH is specified in IEEE floating point format and express in Bytes/second. Delays and delay variation are express in micro-second (µs). Loss is specified in PERCENTAGE ranging from 0 to 50.331642% by step of 0.000003.

link-param neighbor <A.B.C.D> as (0-65535)¶

link-param no neighbor¶: Specifies the remote ASBR IP address and Autonomous System (AS) number for InterASv2 link in OSPF (RFC5392). Note that this option is not yet supported for ISIS (RFC5316).

ip nht resolve-via-default¶: Allows nexthop tracking to resolve via the default route. This is useful when e.g. you want to allow BGP to peer across the default route.

Administrative Distance¶

Administrative distance allows FRR to make decisions about what routes should be installed in the rib based upon the originating protocol. The lowest Admin Distance is the route selected. This is purely a subjective decision about ordering and care has been taken to choose the same distances that other routing suites have choosen.

Protocol	Distance
System	0
Kernel	0
Connect	0
Static	1
NHRP	10
EBGP	20
EIGRP	90
BABEL	100
OSPF	110
ISIS	115
OPENFABRIC	115
RIP	120
Table	150
SHARP	150
IBGP	200
PBR	200

An admin distance of 255 indicates to Zebra that the route should not be installed into the Data Plane. Additionally routes with an admin distance of 255 will not be redistributed.

Zebra does treat Kernel routes as special case for the purposes of Admin Distance. Upon learning about a route that is not originated by FRR we read the metric value as a uint32_t. The top byte of the value is interpreted as the Administrative Distance and the low three bytes are read in as the metric. This special case is to facilitate VRF default routes.

Virtual Routing and Forwarding¶

FRR supports VRF. VRF is a way to separate networking contexts on the same machine. Those networking contexts are associated with separate interfaces, thus making it possible to associate one interface with a specific VRF.

VRF can be used, for example, when instantiating per enterprise networking services, without having to instantiate the physical host machine or the routing management daemons for each enterprise. As a result, interfaces are separate for each set of VRF, and routing daemons can have their own context for each VRF.

This conceptual view introduces the Default VRF case. If the user does not configure any specific VRF, then by default, FRR uses the Default VRF.

Configuring VRF networking contexts can be done in various ways on FRR. The VRF interfaces can be configured by entering in interface configuration mode interface IFNAME vrf VRF.

A VRF backend mode is chosen when running Zebra.

If no option is chosen, then the Linux VRF implementation as references in https://www.kernel.org/doc/Documentation/networking/vrf.txt will be mapped over the Zebra VRF. The routing table associated to that VRF is a Linux table identifier located in the same Linux network namespace where Zebra started.

If the -n option is chosen, then the Linux network namespace will be mapped over the Zebra VRF. That implies that Zebra is able to configure several Linux network namespaces. The routing table associated to that VRF is the whole routing tables located in that namespace. For instance, this mode matches OpenStack Network Namespaces. It matches also OpenFastPath. The default behavior remains Linux VRF which is supported by the Linux kernel community, see https://www.kernel.org/doc/Documentation/networking/vrf.txt.

Because of that difference, there are some subtle differences when running some commands in relationship to VRF. Here is an extract of some of those commands:

vrf VRF¶: This command is available on configuration mode. By default, above command permits accessing the VRF configuration mode. This mode is available for both VRFs. It is to be noted that Zebra does not create Linux VRF. The network administrator can however decide to provision this command in configuration file to provide more clarity about the intended configuration.

netns NAMESPACE¶: This command is based on VRF configuration mode. This command is available when Zebra is run in -n mode. This command reflects which Linux network namespace is to be mapped with Zebra VRF. It is to be noted that Zebra creates and detects added/suppressed VRFs from the Linux environment (in fact, those managed with iproute2). The network administrator can however decide to provision this command in configuration file to provide more clarity about the intended configuration.

show ip route vrf VRF¶: The show command permits dumping the routing table associated to the VRF. If Zebra is launched with default settings, this will be the TABLENO of the VRF configured on the kernel, thanks to information provided in https://www.kernel.org/doc/Documentation/networking/vrf.txt. If Zebra is launched with -n option, this will be the default routing table of the Linux network namespace VRF.

show ip route vrf VRF table TABLENO¶: The show command is only available with -n option. This command will dump the routing table TABLENO of the Linux network namespace VRF.

show ip route vrf VRF tables¶: This command will dump the routing tables within the vrf scope. If vrf all is executed, all routing tables will be dumped.

show <ip|ipv6> route summary [vrf VRF] [table TABLENO] [prefix]¶: This command will dump a summary output of the specified VRF and TABLENO combination. If neither VRF or TABLENO is specified FRR defaults to the default vrf and default table. If prefix is specified dump the number of prefix routes.

By using the -n option, the Linux network namespace will be mapped over the Zebra VRF. One nice feature that is possible by handling Linux network namespace is the ability to name default VRF. At startup, Zebra discovers the available Linux network namespace by parsing folder /var/run/netns. Each file stands for a Linux network namespace, but not all Linux network namespaces are available under that folder. This is the case for default VRF. It is possible to name the default VRF, by creating a file, by executing following commands.

touch /var/run/netns/vrf0
mount --bind /proc/self/ns/net /var/run/netns/vrf0

Above command illustrates what happens when the default VRF is visible under var/run/netns/. Here, the default VRF file is vrf0. At startup, FRR detects the presence of that file. It detects that the file statistics information matches the same file statistics information as /proc/self/ns/net ( through stat() function). As statistics information matches, then vrf0 stands for the new default namespace name. Consequently, the VRF naming Default will be overridden by the new discovered namespace name vrf0.

For those who don’t use VRF backend with Linux network namespace, it is possible to statically configure and recompile FRR. It is possible to choose an alternate name for default VRF. Then, the default VRF naming will automatically be updated with the new name. To illustrate, if you want to recompile with global value, use the following command:

./configure --with-defaultvrfname=global

MPLS Commands¶

You can configure static mpls entries in zebra. Basically, handling MPLS consists of popping, swapping or pushing labels to IP packets.

MPLS Acronyms¶

LSR: Networking devices handling labels used to forward traffic between and through them.
LER: A Labeled edge router is located at the edge of an MPLS network, generally between an IP network and an MPLS network.

MPLS Push Action¶

The push action is generally used for LER devices, which want to encapsulate all traffic for a wished destination into an MPLS label. This action is stored in routing entry, and can be configured like a route:

[no] ip route NETWORK MASK GATEWAY|INTERFACE label LABEL¶

NETWORK and MASK stand for the IP prefix entry to be added as static route entry. GATEWAY is the gateway IP address to reach, in order to reach the prefix. INTERFACE is the interface behind which the prefix is located. LABEL is the MPLS label to use to reach the prefix abovementioned.

You can check that the static entry is stored in the zebra RIB database, by looking at the presence of the entry.

zebra(configure)# ip route 1.1.1.1/32 10.0.1.1 label 777
zebra# show ip route
Codes: K - kernel route, C - connected, S - static, R - RIP,
O - OSPF, I - IS-IS, B - BGP, E - EIGRP, N - NHRP,
T - Table, v - VNC, V - VNC-Direct, A - Babel, D - SHARP,
F - PBR,
> - selected route, * - FIB route

S>* 1.1.1.1/32 [1/0] via 10.0.1.1, r2-eth0, label 777, 00:39:42

MPLS Swap and Pop Action¶

The swap action is generally used for LSR devices, which swap a packet with a label, with an other label. The Pop action is used on LER devices, at the termination of the MPLS traffic; this is used to remove MPLS header.

[no] mpls lsp INCOMING_LABEL GATEWAY OUTGOING_LABEL|explicit-null|implicit-null¶: INCOMING_LABEL and OUTGOING_LABEL are MPLS labels with values ranging from 16 to 1048575. GATEWAY is the gateway IP address where to send MPLS packet. The outgoing label can either be a value or have an explicit-null label header. This specific header can be read by IP devices. The incoming label can also be removed; in that case the implicit-null keyword is used, and the outgoing packet emitted is an IP packet without MPLS header.

You can check that the MPLS actions are stored in the zebra MPLS table, by looking at the presence of the entry.

show mpls table¶

zebra(configure)# mpls lsp 18 10.125.0.2 implicit-null
zebra(configure)# mpls lsp 19 10.125.0.2 20
zebra(configure)# mpls lsp 21 10.125.0.2 explicit-null
zebra# show mpls table
Inbound                            Outbound
Label     Type          Nexthop     Label
--------  -------  ---------------  --------
18     Static       10.125.0.2  implicit-null
19     Static       10.125.0.2  20
21     Static       10.125.0.2  IPv4 Explicit Null

Multicast RIB Commands¶

The Multicast RIB provides a separate table of unicast destinations which is used for Multicast Reverse Path Forwarding decisions. It is used with a multicast source’s IP address, hence contains not multicast group addresses but unicast addresses.

This table is fully separate from the default unicast table. However, RPF lookup can include the unicast table.

WARNING: RPF lookup results are non-responsive in this version of FRR, i.e. multicast routing does not actively react to changes in underlying unicast topology!

ip multicast rpf-lookup-mode MODE¶

no ip multicast rpf-lookup-mode [MODE]¶

MODE sets the method used to perform RPF lookups. Supported modes:

urib-only

Performs the lookup on the Unicast RIB. The Multicast RIB is never used.

mrib-only

Performs the lookup on the Multicast RIB. The Unicast RIB is never used.

mrib-then-urib

Tries to perform the lookup on the Multicast RIB. If any route is found, that route is used. Otherwise, the Unicast RIB is tried.

lower-distance

Performs a lookup on the Multicast RIB and Unicast RIB each. The result with the lower administrative distance is used; if they’re equal, the Multicast RIB takes precedence.

longer-prefix

Performs a lookup on the Multicast RIB and Unicast RIB each. The result with the longer prefix length is used; if they’re equal, the Multicast RIB takes precedence.

The mrib-then-urib setting is the default behavior if nothing is configured. If this is the desired behavior, it should be explicitly configured to make the configuration immune against possible changes in what the default behavior is.

Warning

Unreachable routes do not receive special treatment and do not cause fallback to a second lookup.

show ip rpf ADDR¶

Performs a Multicast RPF lookup, as configured with ip multicast rpf-lookup-mode MODE. ADDR specifies the multicast source address to look up.

> show ip rpf 192.0.2.1
Routing entry for 192.0.2.0/24 using Unicast RIB

Known via "kernel", distance 0, metric 0, best
* 198.51.100.1, via eth0

Indicates that a multicast source lookup for 192.0.2.1 would use an Unicast RIB entry for 192.0.2.0/24 with a gateway of 198.51.100.1.

show ip rpf¶: Prints the entire Multicast RIB. Note that this is independent of the configured RPF lookup mode, the Multicast RIB may be printed yet not used at all.

ip mroute PREFIX NEXTHOP [DISTANCE]¶

no ip mroute PREFIX NEXTHOP [DISTANCE]¶: Adds a static route entry to the Multicast RIB. This performs exactly as the ip route command, except that it inserts the route in the Multicast RIB instead of the Unicast RIB.

zebra Route Filtering¶

Zebra supports prefix-list s and Route Maps s to match routes received from other FRR components. The permit/deny facilities provided by these commands can be used to filter which routes zebra will install in the kernel.

ip protocol PROTOCOL route-map ROUTEMAP¶

Apply a route-map filter to routes for the specified protocol. PROTOCOL can be:

any,
babel,
bgp,
connected,
eigrp,
isis,
kernel,
nhrp,
openfabric,
ospf,
ospf6,
rip,
sharp,
static,
ripng,
table,
vnc.

If you choose any as the option that will cause all protocols that are sending routes to zebra. You can specify a ip protocol PROTOCOL route-map ROUTEMAP on a per vrf basis, by entering this command under vrf mode for the vrf you want to apply the route-map against.

set src ADDRESS¶: Within a route-map, set the preferred source address for matching routes when installing in the kernel.

The following creates a prefix-list that matches all addresses, a route-map that sets the preferred source address, and applies the route-map to all rip routes.

ip prefix-list ANY permit 0.0.0.0/0 le 32
route-map RM1 permit 10
     match ip address prefix-list ANY
     set src 10.0.0.1

ip protocol rip route-map RM1

zebra FIB push interface¶

Zebra supports a ‘FIB push’ interface that allows an external component to learn the forwarding information computed by the FRR routing suite. This is a loadable module that needs to be enabled at startup as described in Loadable Module Support.

In FRR, the Routing Information Base (RIB) resides inside zebra. Routing protocols communicate their best routes to zebra, and zebra computes the best route across protocols for each prefix. This latter information makes up the Forwarding Information Base (FIB). Zebra feeds the FIB to the kernel, which allows the IP stack in the kernel to forward packets according to the routes computed by FRR. The kernel FIB is updated in an OS-specific way. For example, the Netlink interface is used on Linux, and route sockets are used on FreeBSD.

The FIB push interface aims to provide a cross-platform mechanism to support scenarios where the router has a forwarding path that is distinct from the kernel, commonly a hardware-based fast path. In these cases, the FIB needs to be maintained reliably in the fast path as well. We refer to the component that programs the forwarding plane (directly or indirectly) as the Forwarding Plane Manager or FPM.

The FIB push interface comprises of a TCP connection between zebra and the FPM. The connection is initiated by zebra – that is, the FPM acts as the TCP server.

The relevant zebra code kicks in when zebra is configured with the --enable-fpm flag. Zebra periodically attempts to connect to the well-known FPM port. Once the connection is up, zebra starts sending messages containing routes over the socket to the FPM. Zebra sends a complete copy of the forwarding table to the FPM, including routes that it may have picked up from the kernel. The existing interaction of zebra with the kernel remains unchanged – that is, the kernel continues to receive FIB updates as before.

The encapsulation header for the messages exchanged with the FPM is defined by the file fpm/fpm.h in the frr tree. The routes themselves are encoded in Netlink or protobuf format, with Netlink being the default.

Protobuf is one of a number of new serialization formats wherein the message schema is expressed in a purpose-built language. Code for encoding/decoding to/from the wire format is generated from the schema. Protobuf messages can be extended easily while maintaining backward-compatibility with older code. Protobuf has the following advantages over Netlink:

Code for serialization/deserialization is generated automatically. This reduces the likelihood of bugs, allows third-party programs to be integrated quickly, and makes it easy to add fields.
The message format is not tied to an OS (Linux), and can be evolved independently.

As mentioned before, zebra encodes routes sent to the FPM in Netlink format by default. The format can be controlled via the FPM module’s load-time option to zebra, which currently takes the values Netlink and protobuf.

The zebra FPM interface uses replace semantics. That is, if a ‘route add’ message for a prefix is followed by another ‘route add’ message, the information in the second message is complete by itself, and replaces the information sent in the first message.

If the connection to the FPM goes down for some reason, zebra sends the FPM a complete copy of the forwarding table(s) when it reconnects.

Dataplane Commands¶

The zebra dataplane subsystem provides a framework for FIB programming. Zebra uses the dataplane to program the local kernel as it makes changes to objects such as IP routes, MPLS LSPs, and interface IP addresses. The dataplane runs in its own pthread, in order to off-load work from the main zebra pthread.

show zebra dplane [detailed]¶: Display statistics about the updates and events passing through the dataplane subsystem.

show zebra dplane providers¶: Display information about the running dataplane plugins that are providing updates to a FIB. By default, the local kernel plugin is present.

zebra dplane limit [NUMBER]¶: Configure the limit on the number of pending updates that are waiting to be processed by the dataplane pthread.

zebra Terminal Mode Commands¶

show ip route¶: Display current routes which zebra holds in its database.

Router# show ip route
Codes: K - kernel route, C - connected, S - static, R - RIP,
 B - BGP * - FIB route.

K* 0.0.0.0/0        203.181.89.241
S  0.0.0.0/0        203.181.89.1
C* 127.0.0.0/8      lo
C* 203.181.89.240/28      eth0

show ipv6 route¶

show [ip|ipv6] route [PREFIX] [nexthop-group]¶: Display detailed information about a route. If [nexthop-group] is included, it will display the nexthop group ID the route is using as well.

show interface [NAME] [{vrf VRF|brief}] [nexthop-group]¶

show interface [NAME] [{vrf all|brief}] [nexthop-group]¶: Display interface information. If no extra information is added, it will dump information on all interfaces. If [NAME] is specified, it will display detailed information about that single interface. If [nexthop-group] is specified, it will display nexthop groups pointing out that interface.

show ip prefix-list [NAME]¶

show route-map [NAME]¶

show ip protocol¶

show ipforward¶: Display whether the host’s IP forwarding function is enabled or not. Almost any UNIX kernel can be configured with IP forwarding disabled. If so, the box can’t work as a router.

show ipv6forward¶: Display whether the host’s IP v6 forwarding is enabled or not.

show zebra¶: Display various statistics related to the installation and deletion of routes, neighbor updates, and LSP’s into the kernel.

show zebra client [summary]¶: Display statistics about clients that are connected to zebra. This is useful for debugging and seeing how much data is being passed between zebra and it’s clients. If the summary form of the command is choosen a table is displayed with shortened information.

show zebra router table summary¶: Display summarized data about tables created, their afi/safi/tableid and how many routes each table contains. Please note this is the total number of route nodes in the table. Which will be higher than the actual number of routes that are held.

show zebra fpm stats¶: Display statistics related to the zebra code that interacts with the optional Forwarding Plane Manager (FPM) component.

clear zebra fpm stats¶: Reset statistics related to the zebra code that interacts with the optional Forwarding Plane Manager (FPM) component.

show nexthop-group rib [ID] [vrf NAME]¶: Display nexthop groups created by zebra. The [vrf NAME] option is only meaningful if you have started zebra with the –vrfwnetns option as that nexthop groups are per namespace in linux. If you specify singleton you would like to see the singleton nexthop groups that do have an afi.

Router-id¶

Many routing protocols require a router-id to be configured. To have a consistent router-id across all daemons, the following commands are available to configure and display the router-id:

[no] router-id A.B.C.D [vrf NAME]¶: Configure the router-id of this router.

show router-id [vrf NAME]¶: Display the user configured router-id.

Bidirectional Forwarding Detection¶

BFD stands for Bidirectional Forwarding Detection and it is described and extended by the following RFCs:

Currently, there are two implementations of the BFD commands in FRR:

PTM: an external daemon which implements BFD;
bfdd: a BFD implementation that is able to talk with remote peers;

This document will focus on the later implementation: bfdd.

Starting BFD¶

bfdd default configuration file is bfdd.conf. bfdd searches the current directory first then /etc/frr/bfdd.conf. All of bfdd’s command must be configured in bfdd.conf.

bfdd specific invocation options are described below. Common options may also be specified (Common Invocation Options).

--bfdctl <unix-socket>¶

Set the BFD daemon control socket location. If using a non-default socket location:

/usr/lib/frr/bfdd --bfdctl /tmp/bfdd.sock

The default UNIX socket location is:

#define BFDD_CONTROL_SOCKET “/var/run/frr/bfdd.sock”

This option overrides the location addition that the -N option provides to the bfdd.sock

BFDd Commands¶

bfd¶: Opens the BFD daemon configuration node.

peer <A.B.C.D|X:X::X:X> [{multihop|local-address <A.B.C.D|X:X::X:X>|interface IFNAME|vrf NAME}]¶

Creates and configures a new BFD peer to listen and talk to.

multihop tells the BFD daemon that we should expect packets with TTL less than 254 (because it will take more than one hop) and to listen on the multihop port (4784). When using multi-hop mode echo-mode will not work (see RFC 5883 section 3).

local-address provides a local address that we should bind our peer listener to and the address we should use to send the packets. This option is mandatory for IPv6.

interface selects which interface we should use.

vrf selects which domain we want to use.

no peer <A.B.C.D|X:X::X:X>$peer [{multihop|local-address <A.B.C.D|X:X::X:X>$local|interface IFNAME$ifname|vrf NAME$vrf_name}]¶: Stops and removes the selected peer.

show bfd [vrf NAME] peers [json]¶: Show all configured BFD peers information and current status.

show bfd [vrf NAME$vrf_name] peer <WORD$label|<A.B.C.D|X:X::X:X>$peer [{multihop|local-address <A.B.C.D|X:X::X:X>$local|interface IFNAME$ifname}]> [json]¶: Show status for a specific BFD peer.

show bfd [vrf NAME] peers brief [json]¶: Show all configured BFD peers information and current status in brief.

Peer Configurations¶

detect-multiplier (2-255)¶

Configures the detection multiplier to determine packet loss. The remote transmission interval will be multiplied by this value to determine the connection loss detection timer. The default value is 3.

Example: when the local system has detect-multiplier 3 and the remote system has transmission interval 300, the local system will detect failures only after 900 milliseconds without receiving packets.

receive-interval (10-60000)¶: Configures the minimum interval that this system is capable of receiving control packets. The default value is 300 milliseconds.

transmit-interval (10-60000)¶: The minimum transmission interval (less jitter) that this system wants to use to send BFD control packets.

echo-interval (10-60000)¶: Configures the minimal echo receive transmission interval that this system is capable of handling.

[no] echo-mode¶

Enables or disables the echo transmission mode. This mode is disabled by default.

It is recommended that the transmission interval of control packets to be increased after enabling echo-mode to reduce bandwidth usage. For example: transmission-interval 2000.

Echo mode is not supported on multi-hop setups (see RFC 5883 section 3).

[no] shutdown¶: Enables or disables the peer. When the peer is disabled an ‘administrative down’ message is sent to the remote peer.

label WORD¶: Labels a peer with the provided word. This word can be referenced later on other daemons to refer to a specific peer.

BGP BFD Configuration¶

The following commands are available inside the BGP configuration node.

neighbor <A.B.C.D|X:X::X:X|WORD> bfd¶: Listen for BFD events registered on the same target as this BGP neighbor. When BFD peer goes down it immediately asks BGP to shutdown the connection with its neighbor and, when it goes back up, notify BGP to try to connect to it.

no neighbor <A.B.C.D|X:X::X:X|WORD> bfd¶: Removes any notification registration for this neighbor.

neighbor <A.B.C.D|X:X::X:X|WORD> bfd check-control-plane-failure¶: Allow to write CBIT independence in BFD outgoing packets. Also allow to read both C-BIT value of BFD and lookup BGP peer status. This command is useful when a BFD down event is caught, while the BGP peer requested that local BGP keeps the remote BGP entries as staled if such issue is detected. This is the case when graceful restart is enabled, and it is wished to ignore the BD event while waiting for the remote router to restart.

no neighbor <A.B.C.D|X:X::X:X|WORD> bfd check-control-plane-failure¶: Disallow to write CBIT independence in BFD outgoing packets. Also disallow to ignore BFD down notification. This is the default behaviour.

OSPF BFD Configuration¶

The following commands are available inside the interface configuration node.

ip ospf bfd¶: Listen for BFD events on peers created on the interface. Every time a new neighbor is found a BFD peer is created to monitor the link status for fast convergence.

no ip ospf bfd¶: Removes any notification registration for this interface peers.

OSPF6 BFD Configuration¶

The following commands are available inside the interface configuration node.

ipv6 ospf6 bfd¶: Listen for BFD events on peers created on the interface. Every time a new neighbor is found a BFD peer is created to monitor the link status for fast convergence.

no ipv6 ospf6 bfd¶: Removes any notification registration for this interface peers.

PIM BFD Configuration¶

The following commands are available inside the interface configuration node.

ip pim bfd¶: Listen for BFD events on peers created on the interface. Every time a new neighbor is found a BFD peer is created to monitor the link status for fast convergence.

no ip pim bfd¶: Removes any notification registration for this interface peers.

Configuration¶

Before applying bfdd rules to integrated daemons (like BGPd), we must create the corresponding peers inside the bfd configuration node.

Here is an example of BFD configuration:

bfd
 peer 192.168.0.1
   label home-peer
   no shutdown
 !
!
router bgp 65530
 neighbor 192.168.0.1 remote-as 65531
 neighbor 192.168.0.1 bfd
 neighbor 192.168.0.2 remote-as 65530
 neighbor 192.168.0.2 bfd
 neighbor 192.168.0.3 remote-as 65532
 neighbor 192.168.0.3 bfd
!

Peers can be identified by its address (use multihop when you need to specify a multi hop peer) or can be specified manually by a label.

Here are the available peer configurations:

bfd

 ! configure a peer on an specific interface
 peer 192.168.0.1 interface eth0
  no shutdown
 !

 ! configure a multihop peer
 peer 192.168.0.2 multihop local-address 192.168.0.3
   shutdown
 !

 ! configure a peer in a different vrf
 peer 192.168.0.3 vrf foo
  shutdown
 !

 ! configure a peer with every option possible
 peer 192.168.0.4
  label peer-label
  detect-multiplier 50
  receive-interval 60000
  transmit-interval 3000
  shutdown
 !

 ! configure a peer on an interface from a separate vrf
 peer 192.168.0.5 interface eth1 vrf vrf2
  no shutdown
 !

 ! remove a peer
 no peer 192.168.0.3 vrf foo

Status¶

You can inspect the current BFD peer status with the following commands:

frr# show bfd peers
BFD Peers:
        peer 192.168.0.1
                ID: 1
                Remote ID: 1
                Status: up
                Uptime: 1 minute(s), 51 second(s)
                Diagnostics: ok
                Remote diagnostics: ok
                Peer Type: dynamic
                Local timers:
                        Detect-multiplier: 3
                        Receive interval: 300ms
                        Transmission interval: 300ms
                        Echo transmission interval: disabled
                Remote timers:
                        Detect-multiplier: 3
                        Receive interval: 300ms
                        Transmission interval: 300ms
                        Echo transmission interval: 50ms

        peer 192.168.1.1
                label: router3-peer
                ID: 2
                Remote ID: 2
                Status: up
                Uptime: 1 minute(s), 53 second(s)
                Diagnostics: ok
                Remote diagnostics: ok
                Peer Type: configured
                Local timers:
                        Detect-multiplier: 3
                        Receive interval: 300ms
                        Transmission interval: 300ms
                        Echo transmission interval: disabled
                Remote timers:
                        Detect-multiplier: 3
                        Receive interval: 300ms
                        Transmission interval: 300ms
                        Echo transmission interval: 50ms

frr# show bfd peer 192.168.1.1
BFD Peer:
            peer 192.168.1.1
                label: router3-peer
                ID: 2
                Remote ID: 2
                Status: up
                Uptime: 3 minute(s), 4 second(s)
                Diagnostics: ok
                Remote diagnostics: ok
                Peer Type: dynamic
                Local timers:
                        Detect-multiplier: 3
                        Receive interval: 300ms
                        Transmission interval: 300ms
                        Echo transmission interval: disabled
                Remote timers:
                        Detect-multiplier: 3
                        Receive interval: 300ms
                        Transmission interval: 300ms
                        Echo transmission interval: 50ms

frr# show bfd peer 192.168.0.1 json
{"multihop":false,"peer":"192.168.0.1","id":1,"remote-id":1,"status":"up","uptime":161,"diagnostic":"ok","remote-diagnostic":"ok","receive-interval":300,"transmit-interval":300,"echo-interval":50,"detect-multiplier":3,"remote-receive-interval":300,"remote-transmit-interval":300,"remote-echo-interval":50,"remote-detect-multiplier":3,"peer-type":"dynamic"}

You can inspect the current BFD peer status in brief with the following commands:

frr# show bfd peers brief
Session count: 1
SessionId  LocalAddress         PeerAddress      Status
=========  ============         ===========      ======
1          192.168.0.1          192.168.0.2      up

You can also inspect peer session counters with the following commands:

frr# show bfd peers counters
BFD Peers:
     peer 192.168.2.1 interface r2-eth2
             Control packet input: 28 packets
             Control packet output: 28 packets
             Echo packet input: 0 packets
             Echo packet output: 0 packets
             Session up events: 1
             Session down events: 0
             Zebra notifications: 2

     peer 192.168.0.1
             Control packet input: 54 packets
             Control packet output: 103 packets
             Echo packet input: 965 packets
             Echo packet output: 966 packets
             Session up events: 1
             Session down events: 0
             Zebra notifications: 4

frr# show bfd peer 192.168.0.1 counters
     peer 192.168.0.1
             Control packet input: 126 packets
             Control packet output: 247 packets
             Echo packet input: 2409 packets
             Echo packet output: 2410 packets
             Session up events: 1
             Session down events: 0
             Zebra notifications: 4

frr# show bfd peer 192.168.0.1 counters json
{"multihop":false,"peer":"192.168.0.1","control-packet-input":348,"control-packet-output":685,"echo-packet-input":6815,"echo-packet-output":6816,"session-up":1,"session-down":0,"zebra-notifications":4}

You can also clear packet counters per session with the following commands, only the packet counters will be reset:

frr# clear bfd peers counters

frr# show bfd peers counters
BFD Peers:
     peer 192.168.2.1 interface r2-eth2
             Control packet input: 0 packets
             Control packet output: 0 packets
             Echo packet input: 0 packets
             Echo packet output: 0 packets
             Session up events: 1
             Session down events: 0
             Zebra notifications: 2

     peer 192.168.0.1
             Control packet input: 0 packets
             Control packet output: 0 packets
             Echo packet input: 0 packets
             Echo packet output: 0 packets
             Session up events: 1
             Session down events: 0
             Zebra notifications: 4

BGP¶

BGP stands for Border Gateway Protocol. The latest BGP version is 4. BGP-4 is one of the Exterior Gateway Protocols and the de facto standard interdomain routing protocol. BGP-4 is described in RFC 1771 and updated by RFC 4271. RFC 2858 adds multiprotocol support to BGP-4.

Starting BGP¶

The default configuration file of bgpd is bgpd.conf. bgpd searches the current directory first, followed by /etc/frr/bgpd.conf. All of bgpd’s commands must be configured in bgpd.conf when the integrated config is not being used.

bgpd specific invocation options are described below. Common options may also be specified (Common Invocation Options).

-p, --bgp_port <port>¶: Set the bgp protocol’s port number. When port number is 0, that means do not listen bgp port.

-l, --listenon¶: Specify a specific IP address for bgpd to listen on, rather than its default of 0.0.0.0 / ::. This can be useful to constrain bgpd to an internal address, or to run multiple bgpd processes on one host.

-n, --no_kernel¶: Do not install learned routes into the linux kernel. This option is useful for a route-reflector environment or if you are running multiple bgp processes in the same namespace. This option is different than the –no_zebra option in that a ZAPI connection is made.

-S, --skip_runas¶: Skip the normal process of checking capabilities and changing user and group information.

-e, --ecmp¶: Run BGP with a limited ecmp capability, that is different than what BGP was compiled with. The value specified must be greater than 0 and less than or equal to the MULTIPATH_NUM specified on compilation.

-Z, --no_zebra¶: Do not communicate with zebra at all. This is different than the –no_kernel option in that we do not even open a ZAPI connection to the zebra process.

-s, --socket_size¶: When opening tcp connections to our peers, set the socket send buffer size that the kernel will use for the peers socket. This option is only really useful at a very large scale. Experimentation should be done to see if this is helping or not at the scale you are running at.

LABEL MANAGER¶

-I, --int_num¶: Set zclient id. This is required when using Zebra label manager in proxy mode.

Basic Concepts¶

Autonomous Systems¶

From RFC 1930:

An AS is a connected group of one or more IP prefixes run by one or more network operators which has a SINGLE and CLEARLY DEFINED routing policy.

Each AS has an identifying number associated with it called an ASN. This is a two octet value ranging in value from 1 to 65535. The AS numbers 64512 through 65535 are defined as private AS numbers. Private AS numbers must not be advertised on the global Internet.

The ASN is one of the essential elements of BGP. BGP is a distance vector routing protocol, and the AS-Path framework provides distance vector metric and loop detection to BGP.

See also

RFC 1930

Address Families¶

Multiprotocol extensions enable BGP to carry routing information for multiple network layer protocols. BGP supports an Address Family Identifier (AFI) for IPv4 and IPv6. Support is also provided for multiple sets of per-AFI information via the BGP Subsequent Address Family Identifier (SAFI). FRR supports SAFIs for unicast information, labeled information (RFC 3107 and RFC 8277), and Layer 3 VPN information (RFC 4364 and RFC 4659).

Route Selection¶

The route selection process used by FRR’s BGP implementation uses the following decision criterion, starting at the top of the list and going towards the bottom until one of the factors can be used.

Weight check

Prefer higher local weight routes to lower routes.
Local preference check

Prefer higher local preference routes to lower.
Local route check

Prefer local routes (statics, aggregates, redistributed) to received routes.
AS path length check

Prefer shortest hop-count AS_PATHs.
Origin check

Prefer the lowest origin type route. That is, prefer IGP origin routes to EGP, to Incomplete routes.
MED check

Where routes with a MED were received from the same AS, prefer the route with the lowest MED. Multi-Exit Discriminator.
External check

Prefer the route received from an external, eBGP peer over routes received from other types of peers.
IGP cost check

Prefer the route with the lower IGP cost.
Multi-path check

If multi-pathing is enabled, then check whether the routes not yet distinguished in preference may be considered equal. If bgp bestpath as-path multipath-relax is set, all such routes are considered equal, otherwise routes received via iBGP with identical AS_PATHs or routes received from eBGP neighbours in the same AS are considered equal.
Already-selected external check

Where both routes were received from eBGP peers, then prefer the route which is already selected. Note that this check is not applied if bgp bestpath compare-routerid is configured. This check can prevent some cases of oscillation.
Router-ID check

Prefer the route with the lowest router-ID. If the route has an ORIGINATOR_ID attribute, through iBGP reflection, then that router ID is used, otherwise the router-ID of the peer the route was received from is used.
Cluster-List length check

The route with the shortest cluster-list length is used. The cluster-list reflects the iBGP reflection path the route has taken.
Peer address

Prefer the route received from the peer with the higher transport layer address, as a last-resort tie-breaker.

Capability Negotiation¶

When adding IPv6 routing information exchange feature to BGP. There were some proposals. IETF IDR adopted a proposal called Multiprotocol Extension for BGP. The specification is described in RFC 2283. The protocol does not define new protocols. It defines new attributes to existing BGP. When it is used exchanging IPv6 routing information it is called BGP-4+. When it is used for exchanging multicast routing information it is called MBGP.

bgpd supports Multiprotocol Extension for BGP. So if a remote peer supports the protocol, bgpd can exchange IPv6 and/or multicast routing information.

Traditional BGP did not have the feature to detect a remote peer’s capabilities, e.g. whether it can handle prefix types other than IPv4 unicast routes. This was a big problem using Multiprotocol Extension for BGP in an operational network. RFC 2842 adopted a feature called Capability Negotiation. bgpd use this Capability Negotiation to detect the remote peer’s capabilities. If a peer is only configured as an IPv4 unicast neighbor, bgpd does not send these Capability Negotiation packets (at least not unless other optional BGP features require capability negotiation).

By default, FRR will bring up peering with minimal common capability for the both sides. For example, if the local router has unicast and multicast capabilities and the remote router only has unicast capability the local router will establish the connection with unicast only capability. When there are no common capabilities, FRR sends Unsupported Capability error and then resets the connection.

BGP Router Configuration¶

ASN and Router ID¶

First of all you must configure BGP router with the router bgp ASN command. The AS number is an identifier for the autonomous system. The BGP protocol uses the AS number for detecting whether the BGP connection is internal or external.

router bgp ASN¶: Enable a BGP protocol process with the specified ASN. After this statement you can input any BGP Commands.

no router bgp ASN¶: Destroy a BGP protocol process with the specified ASN.

bgp router-id A.B.C.D¶: This command specifies the router-ID. If bgpd connects to zebra it gets interface and address information. In that case default router ID value is selected as the largest IP Address of the interfaces. When router zebra is not enabled bgpd can’t get interface information so router-id is set to 0.0.0.0. So please set router-id by hand.

Multiple Autonomous Systems¶

FRR’s BGP implementation is capable of running multiple autonomous systems at once. Each configured AS corresponds to a Administrative Distance. In the past, to get the same functionality the network administrator had to run a new bgpd process; using VRFs allows multiple autonomous systems to be handled in a single process.

When using multiple autonomous systems, all router config blocks after the first one must specify a VRF to be the target of BGP’s route selection. This VRF must be unique within respect to all other VRFs being used for the same purpose, i.e. two different autonomous systems cannot use the same VRF. However, the same AS can be used with different VRFs.

Note

The separated nature of VRFs makes it possible to peer a single bgpd process to itself, on one machine. Note that this can be done fully within BGP without a corresponding VRF in the kernel or Zebra, which enables some practical use cases such as route reflectors and route servers.

Configuration of additional autonomous systems, or of a router that targets a specific VRF, is accomplished with the following command:

router bgp ASN vrf VRFNAME¶: VRFNAME is matched against VRFs configured in the kernel. When vrf VRFNAME is not specified, the BGP protocol process belongs to the default VRF.

An example configuration with multiple autonomous systems might look like this:

router bgp 1
 neighbor 10.0.0.1 remote-as 20
 neighbor 10.0.0.2 remote-as 30
!
router bgp 2 vrf blue
 neighbor 10.0.0.3 remote-as 40
 neighbor 10.0.0.4 remote-as 50
!
router bgp 3 vrf red
 neighbor 10.0.0.5 remote-as 60
 neighbor 10.0.0.6 remote-as 70
...

See also

VRF Route Leaking

See also

Administrative Distance

Views¶

In addition to supporting multiple autonomous systems, FRR’s BGP implementation also supports views.

BGP views are almost the same as normal BGP processes, except that routes selected by BGP are not installed into the kernel routing table. Each BGP view provides an independent set of routing information which is only distributed via BGP. Multiple views can be supported, and BGP view information is always independent from other routing protocols and Zebra/kernel routes. BGP views use the core instance (i.e., default VRF) for communication with peers.

router bgp AS-NUMBER view NAME¶

Make a new BGP view. You can use an arbitrary word for the NAME. Routes selected by the view are not installed into the kernel routing table.

With this command, you can setup Route Server like below.

!
router bgp 1 view 1
 neighbor 10.0.0.1 remote-as 2
 neighbor 10.0.0.2 remote-as 3
!
router bgp 2 view 2
 neighbor 10.0.0.3 remote-as 4
 neighbor 10.0.0.4 remote-as 5

show [ip] bgp view NAME¶: Display the routing table of BGP view NAME.

Route Selection¶

bgp bestpath as-path confed¶: This command specifies that the length of confederation path sets and sequences should should be taken into account during the BGP best path decision process.

bgp bestpath as-path multipath-relax¶: This command specifies that BGP decision process should consider paths of equal AS_PATH length candidates for multipath computation. Without the knob, the entire AS_PATH must match for multipath computation.

bgp bestpath compare-routerid¶

Ensure that when comparing routes where both are equal on most metrics, including local-pref, AS_PATH length, IGP cost, MED, that the tie is broken based on router-ID.

If this option is enabled, then the already-selected check, where already selected eBGP routes are preferred, is skipped.

If a route has an ORIGINATOR_ID attribute because it has been reflected, that ORIGINATOR_ID will be used. Otherwise, the router-ID of the peer the route was received from will be used.

The advantage of this is that the route-selection (at this point) will be more deterministic. The disadvantage is that a few or even one lowest-ID router may attract all traffic to otherwise-equal paths because of this check. It may increase the possibility of MED or IGP oscillation, unless other measures were taken to avoid these. The exact behaviour will be sensitive to the iBGP and reflection topology.

Administrative Distance Metrics¶

distance bgp (1-255) (1-255) (1-255)¶: This command change distance value of BGP. The arguments are the distance values for for external routes, internal routes and local routes respectively.

distance (1-255) A.B.C.D/M¶

distance (1-255) A.B.C.D/M WORD¶: Sets the administrative distance for a particular route.

Require policy on EBGP¶

[no] bgp ebgp-requires-policy¶: This command requires incoming and outgoing filters to be applied for eBGP sessions. Without the incoming filter, no routes will be accepted. Without the outgoing filter, no routes will be announced.

Reject routes with AS_SET or AS_CONFED_SET types¶

[no] bgp reject-as-sets¶: This command enables rejection of incoming and outgoing routes having AS_SET or AS_CONFED_SET type.

Route Flap Dampening¶

bgp dampening (1-45) (1-20000) (1-20000) (1-255)¶

This command enables BGP route-flap dampening and specifies dampening parameters.

half-life: Half-life time for the penalty
reuse-threshold: Value to start reusing a route
suppress-threshold: Value to start suppressing a route
max-suppress: Maximum duration to suppress a stable route

The route-flap damping algorithm is compatible with RFC 2439. The use of this command is not recommended nowadays.

At the moment, route-flap dampening is not working per VRF and is working only for IPv4 unicast and multicast.

Multi-Exit Discriminator¶

The BGP MED attribute has properties which can cause subtle convergence problems in BGP. These properties and problems have proven to be hard to understand, at least historically, and may still not be widely understood. The following attempts to collect together and present what is known about MED, to help operators and FRR users in designing and configuring their networks.

The BGP MED attribute is intended to allow one AS to indicate its preferences for its ingress points to another AS. The MED attribute will not be propagated on to another AS by the receiving AS - it is ‘non-transitive’ in the BGP sense.

E.g., if AS X and AS Y have 2 different BGP peering points, then AS X might set a MED of 100 on routes advertised at one and a MED of 200 at the other. When AS Y selects between otherwise equal routes to or via AS X, AS Y should prefer to take the path via the lower MED peering of 100 with AS X. Setting the MED allows an AS to influence the routing taken to it within another, neighbouring AS.

In this use of MED it is not really meaningful to compare the MED value on routes where the next AS on the paths differs. E.g., if AS Y also had a route for some destination via AS Z in addition to the routes from AS X, and AS Z had also set a MED, it wouldn’t make sense for AS Y to compare AS Z’s MED values to those of AS X. The MED values have been set by different administrators, with different frames of reference.

The default behaviour of BGP therefore is to not compare MED values across routes received from different neighbouring ASes. In FRR this is done by comparing the neighbouring, left-most AS in the received AS_PATHs of the routes and only comparing MED if those are the same.

Unfortunately, this behaviour of MED, of sometimes being compared across routes and sometimes not, depending on the properties of those other routes, means MED can cause the order of preference over all the routes to be undefined. That is, given routes A, B, and C, if A is preferred to B, and B is preferred to C, then a well-defined order should mean the preference is transitive (in the sense of orders [1]) and that A would be preferred to C.

However, when MED is involved this need not be the case. With MED it is possible that C is actually preferred over A. So A is preferred to B, B is preferred to C, but C is preferred to A. This can be true even where BGP defines a deterministic ‘most preferred’ route out of the full set of A,B,C. With MED, for any given set of routes there may be a deterministically preferred route, but there need not be any way to arrange them into any order of preference. With unmodified MED, the order of preference of routes literally becomes undefined.

That MED can induce non-transitive preferences over routes can cause issues. Firstly, it may be perceived to cause routing table churn locally at speakers; secondly, and more seriously, it may cause routing instability in iBGP topologies, where sets of speakers continually oscillate between different paths.

The first issue arises from how speakers often implement routing decisions. Though BGP defines a selection process that will deterministically select the same route as best at any given speaker, even with MED, that process requires evaluating all routes together. For performance and ease of implementation reasons, many implementations evaluate route preferences in a pair-wise fashion instead. Given there is no well-defined order when MED is involved, the best route that will be chosen becomes subject to implementation details, such as the order the routes are stored in. That may be (locally) non-deterministic, e.g.: it may be the order the routes were received in.

This indeterminism may be considered undesirable, though it need not cause problems. It may mean additional routing churn is perceived, as sometimes more updates may be produced than at other times in reaction to some event .

This first issue can be fixed with a more deterministic route selection that ensures routes are ordered by the neighbouring AS during selection. bgp deterministic-med. This may reduce the number of updates as routes are received, and may in some cases reduce routing churn. Though, it could equally deterministically produce the largest possible set of updates in response to the most common sequence of received updates.

A deterministic order of evaluation tends to imply an additional overhead of sorting over any set of n routes to a destination. The implementation of deterministic MED in FRR scales significantly worse than most sorting algorithms at present, with the number of paths to a given destination. That number is often low enough to not cause any issues, but where there are many paths, the deterministic comparison may quickly become increasingly expensive in terms of CPU.

Deterministic local evaluation can not fix the second, more major, issue of MED however. Which is that the non-transitive preference of routes MED can cause may lead to routing instability or oscillation across multiple speakers in iBGP topologies. This can occur with full-mesh iBGP, but is particularly problematic in non-full-mesh iBGP topologies that further reduce the routing information known to each speaker. This has primarily been documented with iBGP route-reflection topologies. However, any route-hiding technologies potentially could also exacerbate oscillation with MED.

This second issue occurs where speakers each have only a subset of routes, and there are cycles in the preferences between different combinations of routes - as the undefined order of preference of MED allows - and the routes are distributed in a way that causes the BGP speakers to ‘chase’ those cycles. This can occur even if all speakers use a deterministic order of evaluation in route selection.

E.g., speaker 4 in AS A might receive a route from speaker 2 in AS X, and from speaker 3 in AS Y; while speaker 5 in AS A might receive that route from speaker 1 in AS Y. AS Y might set a MED of 200 at speaker 1, and 100 at speaker 3. I.e, using ASN:ID:MED to label the speakers:

.
          /---------------\\
X:2------|--A:4-------A:5--|-Y:1:200
            Y:3:100--|-/   |
          \\---------------/

Assuming all other metrics are equal (AS_PATH, ORIGIN, 0 IGP costs), then based on the RFC4271 decision process speaker 4 will choose X:2 over Y:3:100, based on the lower ID of 2. Speaker 4 advertises X:2 to speaker 5. Speaker 5 will continue to prefer Y:1:200 based on the ID, and advertise this to speaker 4. Speaker 4 will now have the full set of routes, and the Y:1:200 it receives from 5 will beat X:2, but when speaker 4 compares Y:1:200 to Y:3:100 the MED check now becomes active as the ASes match, and now Y:3:100 is preferred. Speaker 4 therefore now advertises Y:3:100 to 5, which will also agrees that Y:3:100 is preferred to Y:1:200, and so withdraws the latter route from 4. Speaker 4 now has only X:2 and Y:3:100, and X:2 beats Y:3:100, and so speaker 4 implicitly updates its route to speaker 5 to X:2. Speaker 5 sees that Y:1:200 beats X:2 based on the ID, and advertises Y:1:200 to speaker 4, and the cycle continues.

The root cause is the lack of a clear order of preference caused by how MED sometimes is and sometimes is not compared, leading to this cycle in the preferences between the routes:

.
 /---> X:2 ---beats---> Y:3:100 --\\
|                                   |
|                                   |
 \\---beats--- Y:1:200 <---beats---/

This particular type of oscillation in full-mesh iBGP topologies can be avoided by speakers preferring already selected, external routes rather than choosing to update to new a route based on a post-MED metric (e.g. router-ID), at the cost of a non-deterministic selection process. FRR implements this, as do many other implementations, so long as it is not overridden by setting bgp bestpath compare-routerid, and see also Route Selection.

However, more complex and insidious cycles of oscillation are possible with iBGP route-reflection, which are not so easily avoided. These have been documented in various places. See, e.g.:

for concrete examples and further references.

There is as of this writing no known way to use MED for its original purpose; and reduce routing information in iBGP topologies; and be sure to avoid the instability problems of MED due the non-transitive routing preferences it can induce; in general on arbitrary networks.

There may be iBGP topology specific ways to reduce the instability risks, even while using MED, e.g.: by constraining the reflection topology and by tuning IGP costs between route-reflector clusters, see RFC 3345 for details. In the near future, the Add-Path extension to BGP may also solve MED oscillation while still allowing MED to be used as intended, by distributing “best-paths per neighbour AS”. This would be at the cost of distributing at least as many routes to all speakers as a full-mesh iBGP would, if not more, while also imposing similar CPU overheads as the “Deterministic MED” feature at each Add-Path reflector.

More generally, the instability problems that MED can introduce on more complex, non-full-mesh, iBGP topologies may be avoided either by:

Setting bgp always-compare-med, however this allows MED to be compared across values set by different neighbour ASes, which may not produce coherent desirable results, of itself.
Effectively ignoring MED by setting MED to the same value (e.g.: 0) using set metric METRIC on all received routes, in combination with setting bgp always-compare-med on all speakers. This is the simplest and most performant way to avoid MED oscillation issues, where an AS is happy not to allow neighbours to inject this problematic metric.

As MED is evaluated after the AS_PATH length check, another possible use for MED is for intra-AS steering of routes with equal AS_PATH length, as an extension of the last case above. As MED is evaluated before IGP metric, this can allow cold-potato routing to be implemented to send traffic to preferred hand-offs with neighbours, rather than the closest hand-off according to the IGP metric.

Note that even if action is taken to address the MED non-transitivity issues, other oscillations may still be possible. E.g., on IGP cost if iBGP and IGP topologies are at cross-purposes with each other - see the Flavel and Roughan paper above for an example. Hence the guideline that the iBGP topology should follow the IGP topology.

bgp deterministic-med¶

Carry out route-selection in way that produces deterministic answers locally, even in the face of MED and the lack of a well-defined order of preference it can induce on routes. Without this option the preferred route with MED may be determined largely by the order that routes were received in.

Setting this option will have a performance cost that may be noticeable when there are many routes for each destination. Currently in FRR it is implemented in a way that scales poorly as the number of routes per destination increases.

The default is that this option is not set.

Note that there are other sources of indeterminism in the route selection process, specifically, the preference for older and already selected routes from eBGP peers, Route Selection.

bgp always-compare-med¶

Always compare the MED on routes, even when they were received from different neighbouring ASes. Setting this option makes the order of preference of routes more defined, and should eliminate MED induced oscillations.

If using this option, it may also be desirable to use set metric METRIC to set MED to 0 on routes received from external neighbours.

This option can be used, together with set metric METRIC to use MED as an intra-AS metric to steer equal-length AS_PATH routes to, e.g., desired exit points.

Networks¶

network A.B.C.D/M¶

This command adds the announcement network.

router bgp 1
 address-family ipv4 unicast
  network 10.0.0.0/8
 exit-address-family

This configuration example says that network 10.0.0.0/8 will be announced to all neighbors. Some vendors’ routers don’t advertise routes if they aren’t present in their IGP routing tables; bgpd doesn’t care about IGP routes when announcing its routes.

no network A.B.C.D/M¶

Route Aggregation¶

Route Aggregation-IPv4 Address Family¶

aggregate-address A.B.C.D/M¶: This command specifies an aggregate address.

aggregate-address A.B.C.D/M route-map NAME¶: Apply a route-map for an aggregated prefix.

aggregate-address A.B.C.D/M as-set¶: This command specifies an aggregate address. Resulting routes include AS set.

aggregate-address A.B.C.D/M summary-only¶: This command specifies an aggregate address. Aggregated routes will not be announce.

no aggregate-address A.B.C.D/M¶

This command removes an aggregate address.

This configuration example setup the aggregate-address under ipv4 address-family.

router bgp 1
 address-family ipv4 unicast
  aggregate-address 10.0.0.0/8
  aggregate-address 20.0.0.0/8 as-set
  aggregate-address 40.0.0.0/8 summary-only
  aggregate-address 50.0.0.0/8 route-map aggr-rmap
 exit-address-family

Route Aggregation-IPv6 Address Family¶

aggregate-address X:X::X:X/M¶: This command specifies an aggregate address.

aggregate-address X:X::X:X/M route-map NAME¶: Apply a route-map for an aggregated prefix.

aggregate-address X:X::X:X/M as-set¶: This command specifies an aggregate address. Resulting routes include AS set.

aggregate-address X:X::X:X/M summary-only¶: This command specifies an aggregate address. Aggregated routes will not be announce.

no aggregate-address X:X::X:X/M¶

This command removes an aggregate address.

This configuration example setup the aggregate-address under ipv6 address-family.

router bgp 1
 address-family ipv6 unicast
  aggregate-address 10::0/64
  aggregate-address 20::0/64 as-set
  aggregate-address 40::0/64 summary-only
  aggregate-address 50::0/64 route-map aggr-rmap
 exit-address-family

Redistribution¶

redistribute kernel¶: Redistribute kernel route to BGP process.

redistribute static¶: Redistribute static route to BGP process.

redistribute connected¶: Redistribute connected route to BGP process.

redistribute rip¶: Redistribute RIP route to BGP process.

redistribute ospf¶: Redistribute OSPF route to BGP process.

redistribute vnc¶: Redistribute VNC routes to BGP process.

redistribute vnc-direct¶: Redistribute VNC direct (not via zebra) routes to BGP process.

update-delay MAX-DELAY¶

update-delay MAX-DELAY ESTABLISH-WAIT¶

This feature is used to enable read-only mode on BGP process restart or when BGP process is cleared using ‘clear ip bgp *’. When applicable, read-only mode would begin as soon as the first peer reaches Established status and a timer for max-delay seconds is started.

During this mode BGP doesn’t run any best-path or generate any updates to its peers. This mode continues until:

All the configured peers, except the shutdown peers, have sent explicit EOR (End-Of-RIB) or an implicit-EOR. The first keep-alive after BGP has reached Established is considered an implicit-EOR. If the establish-wait optional value is given, then BGP will wait for peers to reach established from the beginning of the update-delay till the establish-wait period is over, i.e. the minimum set of established peers for which EOR is expected would be peers established during the establish-wait window, not necessarily all the configured neighbors.
max-delay period is over.

On hitting any of the above two conditions, BGP resumes the decision process and generates updates to its peers.

Default max-delay is 0, i.e. the feature is off by default.

table-map ROUTE-MAP-NAME¶

This feature is used to apply a route-map on route updates from BGP to Zebra. All the applicable match operations are allowed, such as match on prefix, next-hop, communities, etc. Set operations for this attach-point are limited to metric and next-hop only. Any operation of this feature does not affect BGPs internal RIB.

Supported for ipv4 and ipv6 address families. It works on multi-paths as well, however, metric setting is based on the best-path only.

Peers¶

Defining Peers¶

neighbor PEER remote-as ASN¶

Creates a new neighbor whose remote-as is ASN. PEER can be an IPv4 address or an IPv6 address or an interface to use for the connection.

router bgp 1
 neighbor 10.0.0.1 remote-as 2

In this case my router, in AS-1, is trying to peer with AS-2 at 10.0.0.1.

This command must be the first command used when configuring a neighbor. If the remote-as is not specified, bgpd will complain like this:

can't find neighbor 10.0.0.1

neighbor PEER remote-as internal¶: Create a peer as you would when you specify an ASN, except that if the peers ASN is different than mine as specified under the router bgp ASN command the connection will be denied.

neighbor PEER remote-as external¶: Create a peer as you would when you specify an ASN, except that if the peers ASN is the same as mine as specified under the router bgp ASN command the connection will be denied.

[no] bgp listen range <A.B.C.D/M|X:X::X:X/M> peer-group PGNAME¶: Accept connections from any peers in the specified prefix. Configuration from the specified peer-group is used to configure these peers.

Note

When using BGP listen ranges, if the associated peer group has TCP MD5 authentication configured, your kernel must support this on prefixes. On Linux, this support was added in kernel version 4.14. If your kernel does not support this feature you will get a warning in the log file, and the listen range will only accept connections from peers without MD5 configured.

Additionally, we have observed that when using this option at scale (several hundred peers) the kernel may hit its option memory limit. In this situation you will see error messages like:

bgpd: sockopt_tcp_signature: setsockopt(23): Cannot allocate memory

In this case you need to increase the value of the sysctl net.core.optmem_max to allow the kernel to allocate the necessary option memory.

Configuring Peers¶

[no] neighbor PEER shutdown¶: Shutdown the peer. We can delete the neighbor’s configuration by no neighbor PEER remote-as ASN but all configuration of the neighbor will be deleted. When you want to preserve the configuration, but want to drop the BGP peer, use this syntax.

[no] neighbor PEER disable-connected-check¶: Allow peerings between directly connected eBGP peers using loopback addresses.

[no] neighbor PEER ebgp-multihop¶

[no] neighbor PEER description ...¶: Set description of the peer.

[no] neighbor PEER version VERSION¶: Set up the neighbor’s BGP version. version can be 4, 4+ or 4-. BGP version 4 is the default value used for BGP peering. BGP version 4+ means that the neighbor supports Multiprotocol Extensions for BGP-4. BGP version 4- is similar but the neighbor speaks the old Internet-Draft revision 00’s Multiprotocol Extensions for BGP-4. Some routing software is still using this version.

[no] neighbor PEER interface IFNAME¶

When you connect to a BGP peer over an IPv6 link-local address, you have to specify the IFNAME of the interface used for the connection. To specify IPv4 session addresses, see the neighbor PEER update-source command below.

This command is deprecated and may be removed in a future release. Its use should be avoided.

[no] neighbor PEER next-hop-self [all]¶: This command specifies an announced route’s nexthop as being equivalent to the address of the bgp router if it is learned via eBGP. If the optional keyword all is specified the modification is done also for routes learned via iBGP.

[no] neighbor PEER update-source <IFNAME|ADDRESS>¶

Specify the IPv4 source address to use for the BGP session to this neighbour, may be specified as either an IPv4 address directly or as an interface name (in which case the zebra daemon MUST be running in order for bgpd to be able to retrieve interface state).

router bgp 64555
 neighbor foo update-source 192.168.0.1
 neighbor bar update-source lo0

[no] neighbor PEER default-originate¶: bgpd’s default is to not announce the default route (0.0.0.0/0) even if it is in routing table. When you want to announce default routes to the peer, use this command.

neighbor PEER port PORT¶

[no] neighbor PEER password PASSWORD¶: Set a MD5 password to be used with the tcp socket that is being used to connect to the remote peer. Please note if you are using this command with a large number of peers on linux you should consider modifying the net.core.optmem_max sysctl to a larger value to avoid out of memory errors from the linux kernel.

neighbor PEER send-community¶

[no] neighbor PEER weight WEIGHT¶: This command specifies a default weight value for the neighbor’s routes.

[no] neighbor PEER maximum-prefix NUMBER¶

Sets a maximum number of prefixes we can receive from a given peer. If this number is exceeded, the BGP session will be destroyed.

In practice, it is generally preferable to use a prefix-list to limit what prefixes are received from the peer instead of using this knob. Tearing down the BGP session when a limit is exceeded is far more destructive than merely rejecting undesired prefixes. The prefix-list method is also much more granular and offers much smarter matching criterion than number of received prefixes, making it more suited to implementing policy.

[no] neighbor PEER local-as AS-NUMBER [no-prepend] [replace-as]¶

Specify an alternate AS for this BGP process when interacting with the specified peer. With no modifiers, the specified local-as is prepended to the received AS_PATH when receiving routing updates from the peer, and prepended to the outgoing AS_PATH (after the process local AS) when transmitting local routes to the peer.

If the no-prepend attribute is specified, then the supplied local-as is not prepended to the received AS_PATH.

If the replace-as attribute is specified, then only the supplied local-as is prepended to the AS_PATH when transmitting local-route updates to this peer.

Note that replace-as can only be specified if no-prepend is.

This command is only allowed for eBGP peers.

[no] neighbor PEER ttl-security hops NUMBER¶: This command enforces Generalized TTL Security Mechanism (GTSM), as specified in RFC 5082. With this command, only neighbors that are the specified number of hops away will be allowed to become neighbors. This command is mutually exclusive with ebgp-multihop.

[no] neighbor PEER capability extended-nexthop¶: Allow bgp to negotiate the extended-nexthop capability with it’s peer. If you are peering over a v6 LL address then this capability is turned on automatically. If you are peering over a v6 Global Address then turning on this command will allow BGP to install v4 routes with v6 nexthops if you do not have v4 configured on interfaces.

[no] bgp fast-external-failover¶: This command causes bgp to not take down ebgp peers immediately when a link flaps. bgp fast-external-failover is the default and will not be displayed as part of a show run. The no form of the command turns off this ability.

[no] bgp default ipv4-unicast¶: This command allows the user to specify that v4 peering is turned on by default or not. This command defaults to on and is not displayed. The no bgp default ipv4-unicast form of the command is displayed.

[no] neighbor PEER advertisement-interval (0-600)¶: Setup the minimum route advertisement interval(mrai) for the peer in question. This number is between 0 and 600 seconds, with the default advertisement interval being 0.

Peer Filtering¶

neighbor PEER distribute-list NAME [in|out]¶: This command specifies a distribute-list for the peer. direct is in or out.

neighbor PEER prefix-list NAME [in|out]¶

neighbor PEER filter-list NAME [in|out]¶

neighbor PEER route-map NAME [in|out]¶: Apply a route-map on the neighbor. direct must be in or out.

bgp route-reflector allow-outbound-policy¶: By default, attribute modification via route-map policy out is not reflected on reflected routes. This option allows the modifications to be reflected as well. Once enabled, it affects all reflected routes.

[no] neighbor PEER sender-as-path-loop-detection¶

Enable the detection of sender side AS path loops and filter the bad routes before they are sent.

This setting is disabled by default.

Peer Groups¶

Peer groups are used to help improve scaling by generating the same update information to all members of a peer group. Note that this means that the routes generated by a member of a peer group will be sent back to that originating peer with the originator identifier attribute set to indicated the originating peer. All peers not associated with a specific peer group are treated as belonging to a default peer group, and will share updates.

neighbor WORD peer-group¶: This command defines a new peer group.

neighbor PEER peer-group PGNAME¶: This command bind specific peer to peer group WORD.

neighbor PEER solo¶: This command is used to indicate that routes advertised by the peer should not be reflected back to the peer. This command only is only meaningful when there is a single peer defined in the peer-group.

Capability Negotiation¶

neighbor PEER strict-capability-match¶

no neighbor PEER strict-capability-match¶

Strictly compares remote capabilities and local capabilities. If capabilities are different, send Unsupported Capability error then reset connection.

You may want to disable sending Capability Negotiation OPEN message optional parameter to the peer when remote peer does not implement Capability Negotiation. Please use dont-capability-negotiate command to disable the feature.

[no] neighbor PEER dont-capability-negotiate¶

Suppress sending Capability Negotiation as OPEN message optional parameter to the peer. This command only affects the peer is configured other than IPv4 unicast configuration.

When remote peer does not have capability negotiation feature, remote peer will not send any capabilities at all. In that case, bgp configures the peer with configured capabilities.

You may prefer locally configured capabilities more than the negotiated capabilities even though remote peer sends capabilities. If the peer is configured by override-capability, bgpd ignores received capabilities then override negotiated capabilities with configured values.

Additionally the operator should be reminded that this feature fundamentally disables the ability to use widely deployed BGP features. BGP unnumbered, hostname support, AS4, Addpath, Route Refresh, ORF, Dynamic Capabilities, and graceful restart.

neighbor PEER override-capability¶

no neighbor PEER override-capability¶: Override the result of Capability Negotiation with local configuration. Ignore remote peer’s capability value.

AS Path Access Lists¶

AS path access list is user defined AS path.

bgp as-path access-list WORD permit|deny LINE¶: This command defines a new AS path access list.

no bgp as-path access-list WORD¶

no bgp as-path access-list WORD permit|deny LINE¶

Using AS Path in Route Map¶

[no] match as-path WORD¶: For a given as-path, WORD, match it on the BGP as-path given for the prefix and if it matches do normal route-map actions. The no form of the command removes this match from the route-map.

[no] set as-path prepend AS-PATH¶: Prepend the given string of AS numbers to the AS_PATH of the BGP path’s NLRI. The no form of this command removes this set operation from the route-map.

[no] set as-path prepend last-as NUM¶: Prepend the existing last AS number (the leftmost ASN) to the AS_PATH. The no form of this command removes this set operation from the route-map.

Communities Attribute¶

The BGP communities attribute is widely used for implementing policy routing. Network operators can manipulate BGP communities attribute based on their network policy. BGP communities attribute is defined in RFC 1997 and RFC 1998. It is an optional transitive attribute, therefore local policy can travel through different autonomous system.

The communities attribute is a set of communities values. Each community value is 4 octet long. The following format is used to define the community value.

AS:VAL: This format represents 4 octet communities value. AS is high order 2 octet in digit format. VAL is low order 2 octet in digit format. This format is useful to define AS oriented policy value. For example, 7675:80 can be used when AS 7675 wants to pass local policy value 80 to neighboring peer.
internet: internet represents well-known communities value 0.
graceful-shutdown: graceful-shutdown represents well-known communities value GRACEFUL_SHUTDOWN 0xFFFF0000 65535:0. RFC 8326 implements the purpose Graceful BGP Session Shutdown to reduce the amount of lost traffic when taking BGP sessions down for maintenance. The use of the community needs to be supported from your peers side to actually have any effect.
accept-own: accept-own represents well-known communities value ACCEPT_OWN 0xFFFF0001 65535:1. RFC 7611 implements a way to signal to a router to accept routes with a local nexthop address. This can be the case when doing policing and having traffic having a nexthop located in another VRF but still local interface to the router. It is recommended to read the RFC for full details.
route-filter-translated-v4: route-filter-translated-v4 represents well-known communities value ROUTE_FILTER_TRANSLATED_v4 0xFFFF0002 65535:2.
route-filter-v4: route-filter-v4 represents well-known communities value ROUTE_FILTER_v4 0xFFFF0003 65535:3.
route-filter-translated-v6: route-filter-translated-v6 represents well-known communities value ROUTE_FILTER_TRANSLATED_v6 0xFFFF0004 65535:4.
route-filter-v6: route-filter-v6 represents well-known communities value ROUTE_FILTER_v6 0xFFFF0005 65535:5.
llgr-stale: llgr-stale represents well-known communities value LLGR_STALE 0xFFFF0006 65535:6. Assigned and intended only for use with routers supporting the Long-lived Graceful Restart Capability as described in [Draft-IETF-uttaro-idr-bgp-persistence]. Routers receiving routes with this community may (depending on implementation) choose allow to reject or modify routes on the presence or absence of this community.
no-llgr: no-llgr represents well-known communities value NO_LLGR 0xFFFF0007 65535:7. Assigned and intended only for use with routers supporting the Long-lived Graceful Restart Capability as described in [Draft-IETF-uttaro-idr-bgp-persistence]. Routers receiving routes with this community may (depending on implementation) choose allow to reject or modify routes on the presence or absence of this community.
accept-own-nexthop: accept-own-nexthop represents well-known communities value accept-own-nexthop 0xFFFF0008 65535:8. [Draft-IETF-agrewal-idr-accept-own-nexthop] describes how to tag and label VPN routes to be able to send traffic between VRFs via an internal layer 2 domain on the same PE device. Refer to [Draft-IETF-agrewal-idr-accept-own-nexthop] for full details.
blackhole: blackhole represents well-known communities value BLACKHOLE 0xFFFF029A 65535:666. RFC 7999 documents sending prefixes to EBGP peers and upstream for the purpose of blackholing traffic. Prefixes tagged with the this community should normally not be re-advertised from neighbors of the originating network. It is recommended upon receiving prefixes tagged with this community to add NO_EXPORT and NO_ADVERTISE.
no-export: no-export represents well-known communities value NO_EXPORT 0xFFFFFF01. All routes carry this value must not be advertised to outside a BGP confederation boundary. If neighboring BGP peer is part of BGP confederation, the peer is considered as inside a BGP confederation boundary, so the route will be announced to the peer.
no-advertise: no-advertise represents well-known communities value NO_ADVERTISE 0xFFFFFF02. All routes carry this value must not be advertise to other BGP peers.
local-AS: local-AS represents well-known communities value NO_EXPORT_SUBCONFED 0xFFFFFF03. All routes carry this value must not be advertised to external BGP peers. Even if the neighboring router is part of confederation, it is considered as external BGP peer, so the route will not be announced to the peer.
no-peer: no-peer represents well-known communities value NOPEER 0xFFFFFF04 65535:65284. RFC 3765 is used to communicate to another network how the originating network want the prefix propagated.

When the communities attribute is received duplicate community values in the attribute are ignored and value is sorted in numerical order.

[Draft-IETF-uttaro-idr-bgp-persistence]

(1, 2) <https://tools.ietf.org/id/draft-uttaro-idr-bgp-persistence-04.txt>

[Draft-IETF-agrewal-idr-accept-own-nexthop]

(1, 2) <https://tools.ietf.org/id/draft-agrewal-idr-accept-own-nexthop-00.txt>

Community Lists¶

Community lists are user defined lists of community attribute values. These lists can be used for matching or manipulating the communities attribute in UPDATE messages.

There are two types of community list:

standard: This type accepts an explicit value for the attribute.
expanded: This type accepts a regular expression. Because the regex must be interpreted on each use expanded community lists are slower than standard lists.

bgp community-list standard NAME permit|deny COMMUNITY¶: This command defines a new standard community list. COMMUNITY is communities value. The COMMUNITY is compiled into community structure. We can define multiple community list under same name. In that case match will happen user defined order. Once the community list matches to communities attribute in BGP updates it return permit or deny by the community list definition. When there is no matched entry, deny will be returned. When COMMUNITY is empty it matches to any routes.

bgp community-list expanded NAME permit|deny COMMUNITY¶: This command defines a new expanded community list. COMMUNITY is a string expression of communities attribute. COMMUNITY can be a regular expression (BGP Regular Expressions) to match the communities attribute in BGP updates. The expanded community is only used to filter, not set actions.

Deprecated since version 5.0: It is recommended to use the more explicit versions of this command.

bgp community-list NAME permit|deny COMMUNITY¶: When the community list type is not specified, the community list type is automatically detected. If COMMUNITY can be compiled into communities attribute, the community list is defined as a standard community list. Otherwise it is defined as an expanded community list. This feature is left for backward compatibility. Use of this feature is not recommended.

no bgp community-list [standard|expanded] NAME¶: Deletes the community list specified by NAME. All community lists share the same namespace, so it’s not necessary to specify standard or expanded; these modifiers are purely aesthetic.

show bgp community-list [NAME]¶

Displays community list information. When NAME is specified the specified community list’s information is shown.

# show bgp community-list
Named Community standard list CLIST
permit 7675:80 7675:100 no-export
deny internet
  Named Community expanded list EXPAND
permit :

  # show bgp community-list CLIST
  Named Community standard list CLIST
permit 7675:80 7675:100 no-export
deny internet

Numbered Community Lists¶

When number is used for BGP community list name, the number has special meanings. Community list number in the range from 1 and 99 is standard community list. Community list number in the range from 100 to 199 is expanded community list. These community lists are called as numbered community lists. On the other hand normal community lists is called as named community lists.

bgp community-list (1-99) permit|deny COMMUNITY¶: This command defines a new community list. The argument to (1-99) defines the list identifier.

bgp community-list (100-199) permit|deny COMMUNITY¶: This command defines a new expanded community list. The argument to (100-199) defines the list identifier.

Using Communities in Route Maps¶

In Route Maps we can match on or set the BGP communities attribute. Using this feature network operator can implement their network policy based on BGP communities attribute.

The ollowing commands can be used in route maps:

match community WORD exact-match [exact-match]¶: This command perform match to BGP updates using community list WORD. When the one of BGP communities value match to the one of communities value in community list, it is match. When exact-match keyword is specified, match happen only when BGP updates have completely same communities value specified in the community list.

set community <none|COMMUNITY> additive¶

This command sets the community value in BGP updates. If the attribute is already configured, the newly provided value replaces the old one unless the additive keyword is specified, in which case the new value is appended to the existing value.

If none is specified as the community value, the communities attribute is not sent.

It is not possible to set an expanded community list.

set comm-list WORD delete¶: This command remove communities value from BGP communities attribute. The word is community list name. When BGP route’s communities value matches to the community list word, the communities value is removed. When all of communities value is removed eventually, the BGP update’s communities attribute is completely removed.

Example Configuration¶

The following configuration is exemplary of the most typical usage of BGP communities attribute. In the example, AS 7675 provides an upstream Internet connection to AS 100. When the following configuration exists in AS 7675, the network operator of AS 100 can set local preference in AS 7675 network by setting BGP communities attribute to the updates.

router bgp 7675
 neighbor 192.168.0.1 remote-as 100
 address-family ipv4 unicast
  neighbor 192.168.0.1 route-map RMAP in
 exit-address-family
!
bgp community-list 70 permit 7675:70
bgp community-list 70 deny
bgp community-list 80 permit 7675:80
bgp community-list 80 deny
bgp community-list 90 permit 7675:90
bgp community-list 90 deny
!
route-map RMAP permit 10
 match community 70
 set local-preference 70
!
route-map RMAP permit 20
 match community 80
 set local-preference 80
!
route-map RMAP permit 30
 match community 90
 set local-preference 90

The following configuration announces 10.0.0.0/8 from AS 100 to AS 7675. The route has communities value 7675:80 so when above configuration exists in AS 7675, the announced routes’ local preference value will be set to 80.

router bgp 100
 network 10.0.0.0/8
 neighbor 192.168.0.2 remote-as 7675
 address-family ipv4 unicast
  neighbor 192.168.0.2 route-map RMAP out
 exit-address-family
!
ip prefix-list PLIST permit 10.0.0.0/8
!
route-map RMAP permit 10
 match ip address prefix-list PLIST
 set community 7675:80

The following configuration is an example of BGP route filtering using communities attribute. This configuration only permit BGP routes which has BGP communities value 0:80 or 0:90. The network operator can set special internal communities value at BGP border router, then limit the BGP route announcements into the internal network.

router bgp 7675
 neighbor 192.168.0.1 remote-as 100
 address-family ipv4 unicast
  neighbor 192.168.0.1 route-map RMAP in
 exit-address-family
!
bgp community-list 1 permit 0:80 0:90
!
route-map RMAP permit in
 match community 1

The following example filters BGP routes which have a community value of 1:1. When there is no match community-list returns deny. To avoid filtering all routes, a permit line is set at the end of the community-list.

router bgp 7675
 neighbor 192.168.0.1 remote-as 100
 address-family ipv4 unicast
  neighbor 192.168.0.1 route-map RMAP in
 exit-address-family
!
bgp community-list standard FILTER deny 1:1
bgp community-list standard FILTER permit
!
route-map RMAP permit 10
 match community FILTER

The communities value keyword internet has special meanings in standard community lists. In the below example internet matches all BGP routes even if the route does not have communities attribute at all. So community list INTERNET is the same as FILTER in the previous example.

bgp community-list standard INTERNET deny 1:1
bgp community-list standard INTERNET permit internet

The following configuration is an example of communities value deletion. With this configuration the community values 100:1 and 100:2 are removed from BGP updates. For communities value deletion, only permit community-list is used. deny community-list is ignored.

router bgp 7675
 neighbor 192.168.0.1 remote-as 100
 address-family ipv4 unicast
  neighbor 192.168.0.1 route-map RMAP in
 exit-address-family
!
bgp community-list standard DEL permit 100:1 100:2
!
route-map RMAP permit 10
 set comm-list DEL delete

Extended Communities Attribute¶

BGP extended communities attribute is introduced with MPLS VPN/BGP technology. MPLS VPN/BGP expands capability of network infrastructure to provide VPN functionality. At the same time it requires a new framework for policy routing. With BGP Extended Communities Attribute we can use Route Target or Site of Origin for implementing network policy for MPLS VPN/BGP.

BGP Extended Communities Attribute is similar to BGP Communities Attribute. It is an optional transitive attribute. BGP Extended Communities Attribute can carry multiple Extended Community value. Each Extended Community value is eight octet length.

BGP Extended Communities Attribute provides an extended range compared with BGP Communities Attribute. Adding to that there is a type field in each value to provides community space structure.

There are two format to define Extended Community value. One is AS based format the other is IP address based format.

AS:VAL: This is a format to define AS based Extended Community value. AS part is 2 octets Global Administrator subfield in Extended Community value. VAL part is 4 octets Local Administrator subfield. 7675:100 represents AS 7675 policy value 100.
IP-Address:VAL: This is a format to define IP address based Extended Community value. IP-Address part is 4 octets Global Administrator subfield. VAL part is 2 octets Local Administrator subfield.

Extended Community Lists¶

bgp extcommunity-list standard NAME permit|deny EXTCOMMUNITY¶: This command defines a new standard extcommunity-list. extcommunity is extended communities value. The extcommunity is compiled into extended community structure. We can define multiple extcommunity-list under same name. In that case match will happen user defined order. Once the extcommunity-list matches to extended communities attribute in BGP updates it return permit or deny based upon the extcommunity-list definition. When there is no matched entry, deny will be returned. When extcommunity is empty it matches to any routes.

bgp extcommunity-list expanded NAME permit|deny LINE¶: This command defines a new expanded extcommunity-list. line is a string expression of extended communities attribute. line can be a regular expression (BGP Regular Expressions) to match an extended communities attribute in BGP updates.

no bgp extcommunity-list NAME¶

no bgp extcommunity-list standard NAME¶

no bgp extcommunity-list expanded NAME¶: These commands delete extended community lists specified by name. All of extended community lists shares a single name space. So extended community lists can be removed simply specifying the name.

show bgp extcommunity-list¶

show bgp extcommunity-list NAME¶

This command displays current extcommunity-list information. When name is specified the community list’s information is shown.:

# show bgp extcommunity-list

BGP Extended Communities in Route Map¶

match extcommunity WORD¶

set extcommunity rt EXTCOMMUNITY¶: This command set Route Target value.

set extcommunity soo EXTCOMMUNITY¶: This command set Site of Origin value.

Note that the extended expanded community is only used for match rule, not for set actions.

Large Communities Attribute¶

The BGP Large Communities attribute was introduced in Feb 2017 with RFC 8092.

The BGP Large Communities Attribute is similar to the BGP Communities Attribute except that it has 3 components instead of two and each of which are 4 octets in length. Large Communities bring additional functionality and convenience over traditional communities, specifically the fact that the GLOBAL part below is now 4 octets wide allowing seamless use in networks using 4-byte ASNs.

GLOBAL:LOCAL1:LOCAL2

This is the format to define Large Community values. Referencing RFC 8195 the values are commonly referred to as follows:

The GLOBAL part is a 4 octet Global Administrator field, commonly used as the operators AS number.
The LOCAL1 part is a 4 octet Local Data Part 1 subfield referred to as a function.
The LOCAL2 part is a 4 octet Local Data Part 2 field and referred to as the parameter subfield.

As an example, 65551:1:10 represents AS 65551 function 1 and parameter 10. The referenced RFC above gives some guidelines on recommended usage.

Large Community Lists¶

Two types of large community lists are supported, namely standard and expanded.

bgp large-community-list standard NAME permit|deny LARGE-COMMUNITY¶: This command defines a new standard large-community-list. large-community is the Large Community value. We can add multiple large communities under same name. In that case the match will happen in the user defined order. Once the large-community-list matches the Large Communities attribute in BGP updates it will return permit or deny based upon the large-community-list definition. When there is no matched entry, a deny will be returned. When large-community is empty it matches any routes.

bgp large-community-list expanded NAME permit|deny LINE¶: This command defines a new expanded large-community-list. Where line is a string matching expression, it will be compared to the entire Large Communities attribute as a string, with each large-community in order from lowest to highest. line can also be a regular expression which matches this Large Community attribute.

no bgp large-community-list NAME¶

no bgp large-community-list standard NAME¶

no bgp large-community-list expanded NAME¶: These commands delete Large Community lists specified by name. All Large Community lists share a single namespace. This means Large Community lists can be removed by simply specifying the name.

show bgp large-community-list¶

show bgp large-community-list NAME¶: This command display current large-community-list information. When name is specified the community list information is shown.

show ip bgp large-community-info¶: This command displays the current large communities in use.

Large Communities in Route Map¶

match large-community LINE [exact-match]¶: Where line can be a simple string to match, or a regular expression. It is very important to note that this match occurs on the entire large-community string as a whole, where each large-community is ordered from lowest to highest. When exact-match keyword is specified, match happen only when BGP updates have completely same large communities value specified in the large community list.

set large-community LARGE-COMMUNITY¶

set large-community LARGE-COMMUNITY LARGE-COMMUNITY¶

set large-community LARGE-COMMUNITY additive¶: These commands are used for setting large-community values. The first command will overwrite any large-communities currently present. The second specifies two large-communities, which overwrites the current large-community list. The third will add a large-community value without overwriting other values. Multiple large-community values can be specified.

Note that the large expanded community is only used for match rule, not for set actions.

L3VPN VRFs¶

bgpd supports L3VPN VRFs for IPv4 RFC 4364 and IPv6 RFC 4659. L3VPN routes, and their associated VRF MPLS labels, can be distributed to VPN SAFI neighbors in the default, i.e., non VRF, BGP instance. VRF MPLS labels are reached using core MPLS labels which are distributed using LDP or BGP labeled unicast. bgpd also supports inter-VRF route leaking.

VRF Route Leaking¶

BGP routes may be leaked (i.e. copied) between a unicast VRF RIB and the VPN SAFI RIB of the default VRF for use in MPLS-based L3VPNs. Unicast routes may also be leaked between any VRFs (including the unicast RIB of the default BGP instanced). A shortcut syntax is also available for specifying leaking from one VRF to another VRF using the default instance’s VPN RIB as the intemediary. A common application of the VRF-VRF feature is to connect a customer’s private routing domain to a provider’s VPN service. Leaking is configured from the point of view of an individual VRF: import refers to routes leaked from VPN to a unicast VRF, whereas export refers to routes leaked from a unicast VRF to VPN.

Required parameters¶

Routes exported from a unicast VRF to the VPN RIB must be augmented by two parameters:

an RD
an RTLIST

Configuration for these exported routes must, at a minimum, specify these two parameters.

Routes imported from the VPN RIB to a unicast VRF are selected according to their RTLISTs. Routes whose RTLIST contains at least one route-target in common with the configured import RTLIST are leaked. Configuration for these imported routes must specify an RTLIST to be matched.

The RD, which carries no semantic value, is intended to make the route unique in the VPN RIB among all routes of its prefix that originate from all the customers and sites that are attached to the provider’s VPN service. Accordingly, each site of each customer is typically assigned an RD that is unique across the entire provider network.

The RTLIST is a set of route-target extended community values whose purpose is to specify route-leaking policy. Typically, a customer is assigned a single route-target value for import and export to be used at all customer sites. This configuration specifies a simple topology wherein a customer has a single routing domain which is shared across all its sites. More complex routing topologies are possible through use of additional route-targets to augment the leaking of sets of routes in various ways.

When using the shortcut syntax for vrf-to-vrf leaking, the RD and RT are auto-derived.

General configuration¶

Configuration of route leaking between a unicast VRF RIB and the VPN SAFI RIB of the default VRF is accomplished via commands in the context of a VRF address-family:

rd vpn export AS:NN|IP:nn¶: Specifies the route distinguisher to be added to a route exported from the current unicast VRF to VPN.

no rd vpn export [AS:NN|IP:nn]¶: Deletes any previously-configured export route distinguisher.

rt vpn import|export|both RTLIST...¶

Specifies the route-target list to be attached to a route (export) or the route-target list to match against (import) when exporting/importing between the current unicast VRF and VPN.

The RTLIST is a space-separated list of route-targets, which are BGP extended community values as described in Extended Communities Attribute.

no rt vpn import|export|both [RTLIST...]¶: Deletes any previously-configured import or export route-target list.

label vpn export (0..1048575)|auto¶: Enables an MPLS label to be attached to a route exported from the current unicast VRF to VPN. If the value specified is auto, the label value is automatically assigned from a pool maintained by the Zebra daemon. If Zebra is not running, or if this command is not configured, automatic label assignment will not complete, which will block corresponding route export.

no label vpn export [(0..1048575)|auto]¶: Deletes any previously-configured export label.

nexthop vpn export A.B.C.D|X:X::X:X¶: Specifies an optional nexthop value to be assigned to a route exported from the current unicast VRF to VPN. If left unspecified, the nexthop will be set to 0.0.0.0 or 0:0::0:0 (self).

no nexthop vpn export [A.B.C.D|X:X::X:X]¶: Deletes any previously-configured export nexthop.

route-map vpn import|export MAP¶: Specifies an optional route-map to be applied to routes imported or exported between the current unicast VRF and VPN.

no route-map vpn import|export [MAP]¶: Deletes any previously-configured import or export route-map.

import|export vpn¶: Enables import or export of routes between the current unicast VRF and VPN.

no import|export vpn¶: Disables import or export of routes between the current unicast VRF and VPN.

import vrf VRFNAME¶

Shortcut syntax for specifying automatic leaking from vrf VRFNAME to the current VRF using the VPN RIB as intermediary. The RD and RT are auto derived and should not be specified explicitly for either the source or destination VRF’s.

This shortcut syntax mode is not compatible with the explicit import vpn and export vpn statements for the two VRF’s involved. The CLI will disallow attempts to configure incompatible leaking modes.

no import vrf VRFNAME¶: Disables automatic leaking from vrf VRFNAME to the current VRF using the VPN RIB as intermediary.

Ethernet Virtual Network - EVPN¶

EVPN advertise-PIP¶

In a EVPN symmetric routing MLAG deployment, all EVPN routes advertised with anycast-IP as next-hop IP and anycast MAC as the Router MAC (RMAC - in BGP EVPN Extended-Community). EVPN picks up the next-hop IP from the VxLAN interface’s local tunnel IP and the RMAC is obtained from the MAC of the L3VNI’s SVI interface. Note: Next-hop IP is used for EVPN routes whether symmetric routing is deployed or not but the RMAC is only relevant for symmetric routing scenario.

Current behavior is not ideal for Prefix (type-5) and self (type-2) routes. This is because the traffic from remote VTEPs routed sub optimally if they land on the system where the route does not belong.

The advertise-pip feature advertises Prefix (type-5) and self (type-2) routes with system’s individual (primary) IP as the next-hop and individual (system) MAC as Router-MAC (RMAC), while leaving the behavior unchanged for other EVPN routes.

To support this feature there needs to have ability to co-exist a (system-MAC, system-IP) pair with a (anycast-MAC, anycast-IP) pair with the ability to terminate VxLAN-encapsulated packets received for either pair on the same L3VNI (i.e associated VLAN). This capability is need per tenant VRF instance.

To derive the system-MAC and the anycast MAC, there needs to have a separate/additional MAC-VLAN interface corresponding to L3VNI’s SVI. The SVI interface’s MAC address can be interpreted as system-MAC and MAC-VLAN interface’s MAC as anycast MAC.

To derive system-IP and anycast-IP, the default BGP instance’s router-id is used as system-IP and the VxLAN interface’s local tunnel IP as the anycast-IP.

User has an option to configure the system-IP and/or system-MAC value if the auto derived value is not preferred.

Note: By default, advertise-pip feature is enabled and user has an option to disable the feature via configuration CLI. Once the feature is disable under bgp vrf instance or MAC-VLAN interface is not configured, all the routes follow the same behavior of using same next-hop and RMAC values.

[no] advertise-pip [ip <addr> [mac <addr>]]¶

Enables or disables advertise-pip feature, specifiy system-IP and/or system-MAC parameters.

Cisco Compatibility¶

FRR has commands that change some configuration syntax and default behavior to behave more closely to Cisco conventions. These are deprecated and will be removed in a future version of FRR.

Deprecated since version 5.0: Please transition to using the FRR specific syntax for your configuration.

bgp config-type cisco¶

Cisco compatible BGP configuration output.

When this configuration line is specified:

no synchronization is displayed. This command does nothing and is for display purposes only.
no auto-summary is displayed.

The network and aggregate-address arguments are displayed as:

A.B.C.D M.M.M.M

FRR: network 10.0.0.0/8
Cisco: network 10.0.0.0

FRR: aggregate-address 192.168.0.0/24
Cisco: aggregate-address 192.168.0.0 255.255.255.0

Community attribute handling is also different. If no configuration is specified community attribute and extended community attribute are sent to the neighbor. If a user manually disables the feature, the community attribute is not sent to the neighbor. When bgp config-type cisco is specified, the community attribute is not sent to the neighbor by default. To send the community attribute user has to specify neighbor A.B.C.D send-community like so:

!
router bgp 1
 neighbor 10.0.0.1 remote-as 1
 address-family ipv4 unicast
  no neighbor 10.0.0.1 send-community
 exit-address-family
!
router bgp 1
 neighbor 10.0.0.1 remote-as 1
 address-family ipv4 unicast
  neighbor 10.0.0.1 send-community
 exit-address-family
!

Deprecated since version 5.0: Please transition to using the FRR specific syntax for your configuration.

bgp config-type zebra¶: FRR style BGP configuration. This is the default.

Debugging¶

show debug¶: Show all enabled debugs.

[no] debug bgp neighbor-events¶: Enable or disable debugging for neighbor events. This provides general information on BGP events such as peer connection / disconnection, session establishment / teardown, and capability negotiation.

[no] debug bgp updates¶: Enable or disable debugging for BGP updates. This provides information on BGP UPDATE messages transmitted and received between local and remote instances.

[no] debug bgp keepalives¶: Enable or disable debugging for BGP keepalives. This provides information on BGP KEEPALIVE messages transmitted and received between local and remote instances.

[no] debug bgp bestpath <A.B.C.D/M|X:X::X:X/M>¶: Enable or disable debugging for bestpath selection on the specified prefix.

[no] debug bgp nht¶: Enable or disable debugging of BGP nexthop tracking.

[no] debug bgp update-groups¶: Enable or disable debugging of dynamic update groups. This provides general information on group creation, deletion, join and prune events.

[no] debug bgp zebra¶: Enable or disable debugging of communications between bgpd and zebra.

Dumping Messages and Routing Tables¶

dump bgp all PATH [INTERVAL]¶

dump bgp all-et PATH [INTERVAL]¶

no dump bgp all [PATH] [INTERVAL]¶: Dump all BGP packet and events to path file. If interval is set, a new file will be created for echo interval of seconds. The path path can be set with date and time formatting (strftime). The type ‘all-et’ enables support for Extended Timestamp Header (Packet Binary Dump Format).

dump bgp updates PATH [INTERVAL]¶

dump bgp updates-et PATH [INTERVAL]¶

no dump bgp updates [PATH] [INTERVAL]¶: Dump only BGP updates messages to path file. If interval is set, a new file will be created for echo interval of seconds. The path path can be set with date and time formatting (strftime). The type ‘updates-et’ enables support for Extended Timestamp Header (Packet Binary Dump Format).

dump bgp routes-mrt PATH¶

dump bgp routes-mrt PATH INTERVAL¶

no dump bgp route-mrt [PATH] [INTERVAL]¶

Dump whole BGP routing table to path. This is heavy process. The path path can be set with date and time formatting (strftime). If interval is set, a new file will be created for echo interval of seconds.

Note: the interval variable can also be set using hours and minutes: 04h20m00.

Other BGP Commands¶

The following are available in the top level enable mode:

clear bgp *¶: Clear all peers.

clear bgp ipv4|ipv6 *¶: Clear all peers with this address-family activated.

clear bgp ipv4|ipv6 unicast *¶: Clear all peers with this address-family and sub-address-family activated.

clear bgp ipv4|ipv6 PEER¶: Clear peers with address of X.X.X.X and this address-family activated.

clear bgp ipv4|ipv6 unicast PEER¶: Clear peer with address of X.X.X.X and this address-family and sub-address-family activated.

clear bgp ipv4|ipv6 PEER soft|in|out¶: Clear peer using soft reconfiguration in this address-family.

clear bgp ipv4|ipv6 unicast PEER soft|in|out¶: Clear peer using soft reconfiguration in this address-family and sub-address-family.

The following are available in the router bgp mode:

write-quanta (1-64)¶: BGP message Tx I/O is vectored. This means that multiple packets are written to the peer socket at the same time each I/O cycle, in order to minimize system call overhead. This value controls how many are written at a time. Under certain load conditions, reducing this value could make peer traffic less ‘bursty’. In practice, leave this settings on the default (64) unless you truly know what you are doing.

read-quanta (1-10)¶: Unlike Tx, BGP Rx traffic is not vectored. Packets are read off the wire one at a time in a loop. This setting controls how many iterations the loop runs for. As with write-quanta, it is best to leave this setting on the default.

Displaying BGP Information¶

The following four commands display the IPv6 and IPv4 routing tables, depending on whether or not the ip keyword is used. Actually, show ip bgp command was used on older Quagga routing daemon project, while show bgp command is the new format. The choice has been done to keep old format with IPv4 routing table, while new format displays IPv6 routing table.

show ip bgp¶

show ip bgp A.B.C.D¶

show bgp¶

show bgp X:X::X:X¶

These commands display BGP routes. When no route is specified, the default is to display all BGP routes.

BGP table version is 0, local router ID is 10.1.1.1
   Status codes: s suppressed, d damped, h history, * valid, > best, i - internal
   Origin codes: i - IGP, e - EGP, ? - incomplete

Network    Next Hop      Metric LocPrf Weight Path
   \*> 1.1.1.1/32       0.0.0.0      0   32768 i

   Total number of prefixes 1

Some other commands provide additional options for filtering the output.

show [ip] bgp regexp LINE¶: This command displays BGP routes using AS path regular expression (BGP Regular Expressions).

show [ip] bgp summary¶: Show a bgp peer summary for the specified address family.

The old command structure show ip bgp may be removed in the future and should no longer be used. In order to reach the other BGP routing tables other than the IPv6 routing table given by show bgp, the new command structure is extended with show bgp [afi] [safi].

show bgp [afi] [safi]¶

show bgp <ipv4|ipv6> <unicast|multicast|vpn|labeled-unicast>¶: These commands display BGP routes for the specific routing table indicated by the selected afi and the selected safi. If no afi and no safi value is given, the command falls back to the default IPv6 routing table

show bgp [afi] [safi] summary¶: Show a bgp peer summary for the specified address family, and subsequent address-family.

show bgp [afi] [safi] summary failed [json]¶: Show a bgp peer summary for peers that are not succesfully exchanging routes for the specified address family, and subsequent address-family.

show bgp [afi] [safi] neighbor [PEER]¶: This command shows information on a specific BGP peer of the relevant afi and safi selected.

show bgp [afi] [safi] dampening dampened-paths¶: Display paths suppressed due to dampening of the selected afi and safi selected.

show bgp [afi] [safi] dampening flap-statistics¶: Display flap statistics of routes of the selected afi and safi selected.

Displaying Routes by Community Attribute¶

The following commands allow displaying routes based on their community attribute.

show [ip] bgp <ipv4|ipv6> community¶

show [ip] bgp <ipv4|ipv6> community COMMUNITY¶

show [ip] bgp <ipv4|ipv6> community COMMUNITY exact-match¶: These commands display BGP routes which have the community attribute. attribute. When COMMUNITY is specified, BGP routes that match that community are displayed. When exact-match is specified, it display only routes that have an exact match.

show [ip] bgp <ipv4|ipv6> community-list WORD¶

show [ip] bgp <ipv4|ipv6> community-list WORD exact-match¶: These commands display BGP routes for the address family specified that match the specified community list. When exact-match is specified, it displays only routes that have an exact match.

Displaying Routes by Large Community Attribute¶

The following commands allow displaying routes based on their large community attribute.

show [ip] bgp <ipv4|ipv6> large-community¶

show [ip] bgp <ipv4|ipv6> large-community LARGE-COMMUNITY¶

show [ip] bgp <ipv4|ipv6> large-community LARGE-COMMUNITY exact-match¶

show [ip] bgp <ipv4|ipv6> large-community LARGE-COMMUNITY json¶: These commands display BGP routes which have the large community attribute. attribute. When LARGE-COMMUNITY is specified, BGP routes that match that large community are displayed. When exact-match is specified, it display only routes that have an exact match. When json is specified, it display routes in json format.

show [ip] bgp <ipv4|ipv6> large-community-list WORD¶

show [ip] bgp <ipv4|ipv6> large-community-list WORD exact-match¶

show [ip] bgp <ipv4|ipv6> large-community-list WORD json¶: These commands display BGP routes for the address family specified that match the specified large community list. When exact-match is specified, it displays only routes that have an exact match. When json is specified, it display routes in json format.

Displaying Routes by AS Path¶

show bgp ipv4|ipv6 regexp LINE¶: This commands displays BGP routes that matches a regular expression line (BGP Regular Expressions).

show [ip] bgp ipv4 vpn¶

show [ip] bgp ipv6 vpn¶: Print active IPV4 or IPV6 routes advertised via the VPN SAFI.

show bgp ipv4 vpn summary¶

show bgp ipv6 vpn summary¶: Print a summary of neighbor connections for the specified AFI/SAFI combination.

Displaying Update Group Information¶

..index:: show bgp update-groups SUBGROUP-ID [advertise-queue|advertised-routes|packet-queue] ..clicmd:: show bgp update-groups [advertise-queue|advertised-routes|packet-queue]

Display Information about each individual update-group being used. If SUBGROUP-ID is specified only display about that particular group. If advertise-queue is specified the list of routes that need to be sent to the peers in the update-group is displayed, advertised-routes means the list of routes we have sent to the peers in the update-group and packet-queue specifies the list of packets in the queue to be sent.

..index:: show bgp update-groups statistics ..clicmd:: show bgp update-groups statistics

Display Information about update-group events in FRR.

Route Reflector¶

BGP routers connected inside the same AS through BGP belong to an internal BGP session, or IBGP. In order to prevent routing table loops, IBGP does not advertise IBGP-learned routes to other routers in the same session. As such, IBGP requires a full mesh of all peers. For large networks, this quickly becomes unscalable. Introducing route reflectors removes the need for the full-mesh.

When route reflectors are configured, these will reflect the routes announced by the peers configured as clients. A route reflector client is configured with:

neighbor PEER route-reflector-client¶

no neighbor PEER route-reflector-client¶

To avoid single points of failure, multiple route reflectors can be configured.

A cluster is a collection of route reflectors and their clients, and is used by route reflectors to avoid looping.

bgp cluster-id A.B.C.D¶

Routing Policy¶

You can set different routing policy for a peer. For example, you can set different filter for a peer.

!
router bgp 1 view 1
 neighbor 10.0.0.1 remote-as 2
 address-family ipv4 unicast
  neighbor 10.0.0.1 distribute-list 1 in
 exit-address-family
!
router bgp 1 view 2
 neighbor 10.0.0.1 remote-as 2
 address-family ipv4 unicast
  neighbor 10.0.0.1 distribute-list 2 in
 exit-address-family

This means BGP update from a peer 10.0.0.1 goes to both BGP view 1 and view 2. When the update is inserted into view 1, distribute-list 1 is applied. On the other hand, when the update is inserted into view 2, distribute-list 2 is applied.

BGP Regular Expressions¶

BGP regular expressions are based on POSIX 1003.2 regular expressions. The following description is just a quick subset of the POSIX regular expressions.

.*: Matches any single character.
*: Matches 0 or more occurrences of pattern.
+: Matches 1 or more occurrences of pattern.

?: Match 0 or 1 occurrences of pattern.

^: Matches the beginning of the line.

$: Matches the end of the line.

_: The _ character has special meanings in BGP regular expressions. It matches to space and comma , and AS set delimiter { and } and AS confederation delimiter ( and ). And it also matches to the beginning of the line and the end of the line. So _ can be used for AS value boundaries match. This character technically evaluates to (^|[,{}()]|$).

Miscellaneous Configuration Examples¶

Example of a session to an upstream, advertising only one prefix to it.

router bgp 64512
 bgp router-id 10.236.87.1
 neighbor upstream peer-group
 neighbor upstream remote-as 64515
 neighbor upstream capability dynamic
 neighbor 10.1.1.1 peer-group upstream
 neighbor 10.1.1.1 description ACME ISP

 address-family ipv4 unicast
  network 10.236.87.0/24
  neighbor upstream prefix-list pl-allowed-adv out
 exit-address-family
!
ip prefix-list pl-allowed-adv seq 5 permit 82.195.133.0/25
ip prefix-list pl-allowed-adv seq 10 deny any

A more complex example including upstream, peer and customer sessions advertising global prefixes and NO_EXPORT prefixes and providing actions for customer routes based on community values. Extensive use is made of route-maps and the ‘call’ feature to support selective advertising of prefixes. This example is intended as guidance only, it has NOT been tested and almost certainly contains silly mistakes, if not serious flaws.

router bgp 64512
 bgp router-id 10.236.87.1
 neighbor upstream capability dynamic
 neighbor cust capability dynamic
 neighbor peer capability dynamic
 neighbor 10.1.1.1 remote-as 64515
 neighbor 10.1.1.1 peer-group upstream
 neighbor 10.2.1.1 remote-as 64516
 neighbor 10.2.1.1 peer-group upstream
 neighbor 10.3.1.1 remote-as 64517
 neighbor 10.3.1.1 peer-group cust-default
 neighbor 10.3.1.1 description customer1
 neighbor 10.4.1.1 remote-as 64518
 neighbor 10.4.1.1 peer-group cust
 neighbor 10.4.1.1 description customer2
 neighbor 10.5.1.1 remote-as 64519
 neighbor 10.5.1.1 peer-group peer
 neighbor 10.5.1.1 description peer AS 1
 neighbor 10.6.1.1 remote-as 64520
 neighbor 10.6.1.1 peer-group peer
 neighbor 10.6.1.1 description peer AS 2

 address-family ipv4 unicast
  network 10.123.456.0/24
  network 10.123.456.128/25 route-map rm-no-export
  neighbor upstream route-map rm-upstream-out out
  neighbor cust route-map rm-cust-in in
  neighbor cust route-map rm-cust-out out
  neighbor cust send-community both
  neighbor peer route-map rm-peer-in in
  neighbor peer route-map rm-peer-out out
  neighbor peer send-community both
  neighbor 10.3.1.1 prefix-list pl-cust1-network in
  neighbor 10.4.1.1 prefix-list pl-cust2-network in
  neighbor 10.5.1.1 prefix-list pl-peer1-network in
  neighbor 10.6.1.1 prefix-list pl-peer2-network in
 exit-address-family
!
ip prefix-list pl-default permit 0.0.0.0/0
!
ip prefix-list pl-upstream-peers permit 10.1.1.1/32
ip prefix-list pl-upstream-peers permit 10.2.1.1/32
!
ip prefix-list pl-cust1-network permit 10.3.1.0/24
ip prefix-list pl-cust1-network permit 10.3.2.0/24
!
ip prefix-list pl-cust2-network permit 10.4.1.0/24
!
ip prefix-list pl-peer1-network permit 10.5.1.0/24
ip prefix-list pl-peer1-network permit 10.5.2.0/24
ip prefix-list pl-peer1-network permit 192.168.0.0/24
!
ip prefix-list pl-peer2-network permit 10.6.1.0/24
ip prefix-list pl-peer2-network permit 10.6.2.0/24
ip prefix-list pl-peer2-network permit 192.168.1.0/24
ip prefix-list pl-peer2-network permit 192.168.2.0/24
ip prefix-list pl-peer2-network permit 172.16.1/24
!
ip as-path access-list asp-own-as permit ^$
ip as-path access-list asp-own-as permit _64512_
!
! #################################################################
! Match communities we provide actions for, on routes receives from
! customers. Communities values of <our-ASN>:X, with X, have actions:
!
! 100 - blackhole the prefix
! 200 - set no_export
! 300 - advertise only to other customers
! 400 - advertise only to upstreams
! 500 - set no_export when advertising to upstreams
! 2X00 - set local_preference to X00
!
! blackhole the prefix of the route
bgp community-list standard cm-blackhole permit 64512:100
!
! set no-export community before advertising
bgp community-list standard cm-set-no-export permit 64512:200
!
! advertise only to other customers
bgp community-list standard cm-cust-only permit 64512:300
!
! advertise only to upstreams
bgp community-list standard cm-upstream-only permit 64512:400
!
! advertise to upstreams with no-export
bgp community-list standard cm-upstream-noexport permit 64512:500
!
! set local-pref to least significant 3 digits of the community
bgp community-list standard cm-prefmod-100 permit 64512:2100
bgp community-list standard cm-prefmod-200 permit 64512:2200
bgp community-list standard cm-prefmod-300 permit 64512:2300
bgp community-list standard cm-prefmod-400 permit 64512:2400
bgp community-list expanded cme-prefmod-range permit 64512:2...
!
! Informational communities
!
! 3000 - learned from upstream
! 3100 - learned from customer
! 3200 - learned from peer
!
bgp community-list standard cm-learnt-upstream permit 64512:3000
bgp community-list standard cm-learnt-cust permit 64512:3100
bgp community-list standard cm-learnt-peer permit 64512:3200
!
! ###################################################################
! Utility route-maps
!
! These utility route-maps generally should not used to permit/deny
! routes, i.e. they do not have meaning as filters, and hence probably
! should be used with 'on-match next'. These all finish with an empty
! permit entry so as not interfere with processing in the caller.
!
route-map rm-no-export permit 10
 set community additive no-export
route-map rm-no-export permit 20
!
route-map rm-blackhole permit 10
 description blackhole, up-pref and ensure it cannot escape this AS
 set ip next-hop 127.0.0.1
 set local-preference 10
 set community additive no-export
route-map rm-blackhole permit 20
!
! Set local-pref as requested
route-map rm-prefmod permit 10
 match community cm-prefmod-100
 set local-preference 100
route-map rm-prefmod permit 20
 match community cm-prefmod-200
 set local-preference 200
route-map rm-prefmod permit 30
 match community cm-prefmod-300
 set local-preference 300
route-map rm-prefmod permit 40
 match community cm-prefmod-400
 set local-preference 400
route-map rm-prefmod permit 50
!
! Community actions to take on receipt of route.
route-map rm-community-in permit 10
 description check for blackholing, no point continuing if it matches.
 match community cm-blackhole
 call rm-blackhole
route-map rm-community-in permit 20
 match community cm-set-no-export
 call rm-no-export
 on-match next
route-map rm-community-in permit 30
 match community cme-prefmod-range
 call rm-prefmod
route-map rm-community-in permit 40
!
! #####################################################################
! Community actions to take when advertising a route.
! These are filtering route-maps,
!
! Deny customer routes to upstream with cust-only set.
route-map rm-community-filt-to-upstream deny 10
 match community cm-learnt-cust
 match community cm-cust-only
route-map rm-community-filt-to-upstream permit 20
!
! Deny customer routes to other customers with upstream-only set.
route-map rm-community-filt-to-cust deny 10
 match community cm-learnt-cust
 match community cm-upstream-only
route-map rm-community-filt-to-cust permit 20
!
! ###################################################################
! The top-level route-maps applied to sessions. Further entries could
! be added obviously..
!
! Customers
route-map rm-cust-in permit 10
 call rm-community-in
 on-match next
route-map rm-cust-in permit 20
 set community additive 64512:3100
route-map rm-cust-in permit 30
!
route-map rm-cust-out permit 10
 call rm-community-filt-to-cust
 on-match next
route-map rm-cust-out permit 20
!
! Upstream transit ASes
route-map rm-upstream-out permit 10
 description filter customer prefixes which are marked cust-only
 call rm-community-filt-to-upstream
 on-match next
route-map rm-upstream-out permit 20
 description only customer routes are provided to upstreams/peers
 match community cm-learnt-cust
!
! Peer ASes
! outbound policy is same as for upstream
route-map rm-peer-out permit 10
 call rm-upstream-out
!
route-map rm-peer-in permit 10
 set community additive 64512:3200

Example of how to set up a 6-Bone connection.

! bgpd configuration
! ==================
!
! MP-BGP configuration
!
router bgp 7675
 bgp router-id 10.0.0.1
 neighbor 3ffe:1cfa:0:2:2a0:c9ff:fe9e:f56 remote-as `as-number`
!
 address-family ipv6
 network 3ffe:506::/32
 neighbor 3ffe:1cfa:0:2:2a0:c9ff:fe9e:f56 activate
 neighbor 3ffe:1cfa:0:2:2a0:c9ff:fe9e:f56 route-map set-nexthop out
 neighbor 3ffe:1cfa:0:2:2c0:4fff:fe68:a231 remote-as `as-number`
 neighbor 3ffe:1cfa:0:2:2c0:4fff:fe68:a231 route-map set-nexthop out
 exit-address-family
!
ipv6 access-list all permit any
!
! Set output nexthop address.
!
route-map set-nexthop permit 10
 match ipv6 address all
 set ipv6 nexthop global 3ffe:1cfa:0:2:2c0:4fff:fe68:a225
 set ipv6 nexthop local fe80::2c0:4fff:fe68:a225
!
log file bgpd.log
!

Configuring FRR as a Route Server¶

The purpose of a Route Server is to centralize the peerings between BGP speakers. For example if we have an exchange point scenario with four BGP speakers, each of which maintaining a BGP peering with the other three (Full Mesh), we can convert it into a centralized scenario where each of the four establishes a single BGP peering against the Route Server (Route server and clients).

We will first describe briefly the Route Server model implemented by FRR. We will explain the commands that have been added for configuring that model. And finally we will show a full example of FRR configured as Route Server.

Description of the Route Server model¶

First we are going to describe the normal processing that BGP announcements suffer inside a standard BGP speaker, as shown in Announcement processing inside a ‘normal’ BGP speaker, it consists of three steps:

When an announcement is received from some peer, the In filters configured for that peer are applied to the announcement. These filters can reject the announcement, accept it unmodified, or accept it with some of its attributes modified.
The announcements that pass the In filters go into the Best Path Selection process, where they are compared to other announcements referred to the same destination that have been received from different peers (in case such other announcements exist). For each different destination, the announcement which is selected as the best is inserted into the BGP speaker’s Loc-RIB.
The routes which are inserted in the Loc-RIB are considered for announcement to all the peers (except the one from which the route came). This is done by passing the routes in the Loc-RIB through the Out filters corresponding to each peer. These filters can reject the route, accept it unmodified, or accept it with some of its attributes modified. Those routes which are accepted by the Out filters of a peer are announced to that peer.

Announcement processing inside a ‘normal’ BGP speaker

Full Mesh

Route server and clients

Of course we want that the routing tables obtained in each of the routers are the same when using the route server than when not. But as a consequence of having a single BGP peering (against the route server), the BGP speakers can no longer distinguish from/to which peer each announce comes/goes.

This means that the routers connected to the route server are not able to apply by themselves the same input/output filters as in the full mesh scenario, so they have to delegate those functions to the route server.

Even more, the ‘best path’ selection must be also performed inside the route server on behalf of its clients. The reason is that if, after applying the filters of the announcer and the (potential) receiver, the route server decides to send to some client two or more different announcements referred to the same destination, the client will only retain the last one, considering it as an implicit withdrawal of the previous announcements for the same destination. This is the expected behavior of a BGP speaker as defined in RFC 1771, and even though there are some proposals of mechanisms that permit multiple paths for the same destination to be sent through a single BGP peering, none are currently supported by most existing BGP implementations.

As a consequence a route server must maintain additional information and perform additional tasks for a RS-client that those necessary for common BGP peerings. Essentially a route server must:

Maintain a separated Routing Information Base (Loc-RIB) for each peer configured as RS-client, containing the routes selected as a result of the ‘Best Path Selection’ process that is performed on behalf of that RS-client.
Whenever it receives an announcement from a RS-client, it must consider it for the Loc-RIBs of the other RS-clients.
- This means that for each of them the route server must pass the announcement through the appropriate Out filter of the announcer.
- Then through the appropriate In filter of the potential receiver.
- Only if the announcement is accepted by both filters it will be passed to the ‘Best Path Selection’ process.
- Finally, it might go into the Loc-RIB of the receiver.

When we talk about the ‘appropriate’ filter, both the announcer and the receiver of the route must be taken into account. Suppose that the route server receives an announcement from client A, and the route server is considering it for the Loc-RIB of client B. The filters that should be applied are the same that would be used in the full mesh scenario, i.e., first the Out filter of router A for announcements going to router B, and then the In filter of router B for announcements coming from router A.

We call ‘Export Policy’ of a RS-client to the set of Out filters that the client would use if there was no route server. The same applies for the ‘Import Policy’ of a RS-client and the set of In filters of the client if there was no route server.

It is also common to demand from a route server that it does not modify some BGP attributes (next-hop, as-path and MED) that are usually modified by standard BGP speakers before announcing a route.

The announcement processing model implemented by FRR is shown in Announcement processing model implemented by the Route Server. The figure shows a mixture of RS-clients (B, C and D) with normal BGP peers (A). There are some details that worth additional comments:

Announcements coming from a normal BGP peer are also considered for the Loc-RIBs of all the RS-clients. But logically they do not pass through any export policy.
Those peers that are configured as RS-clients do not receive any announce from the Main Loc-RIB.
Apart from import and export policies, In and Out filters can also be set for RS-clients. In filters might be useful when the route server has also normal BGP peers. On the other hand, Out filters for RS-clients are probably unnecessary, but we decided not to remove them as they do not hurt anybody (they can always be left empty).

Announcement processing model implemented by the Route Server

Commands for configuring a Route Server¶

Now we will describe the commands that have been added to frr in order to support the route server features.

neighbor PEER-GROUP route-server-client¶

neighbor A.B.C.D route-server-client¶

neighbor X:X::X:X route-server-client¶

This command configures the peer given by peer, A.B.C.D or X:X::X:X as an RS-client.

Actually this command is not new, it already existed in standard FRR. It enables the transparent mode for the specified peer. This means that some BGP attributes (as-path, next-hop and MED) of the routes announced to that peer are not modified.

With the route server patch, this command, apart from setting the transparent mode, creates a new Loc-RIB dedicated to the specified peer (those named Loc-RIB for X in Announcement processing model implemented by the Route Server.). Starting from that moment, every announcement received by the route server will be also considered for the new Loc-RIB.

neigbor A.B.C.D|X.X::X.X|peer-group route-map WORD import|export¶: This set of commands can be used to specify the route-map that represents the Import or Export policy of a peer which is configured as a RS-client (with the previous command).

match peer A.B.C.D|X:X::X:X¶

This is a new match statement for use in route-maps, enabling them to describe import/export policies. As we said before, an import/export policy represents a set of input/output filters of the RS-client. This statement makes possible that a single route-map represents the full set of filters that a BGP speaker would use for its different peers in a non-RS scenario.

The match peer statement has different semantics whether it is used inside an import or an export route-map. In the first case the statement matches if the address of the peer who sends the announce is the same that the address specified by {A.B.C.D|X:X::X:X}. For export route-maps it matches when {A.B.C.D|X:X::X:X} is the address of the RS-Client into whose Loc-RIB the announce is going to be inserted (how the same export policy is applied before different Loc-RIBs is shown in Announcement processing model implemented by the Route Server.).

call WORD¶: This command (also used inside a route-map) jumps into a different route-map, whose name is specified by WORD. When the called route-map finishes, depending on its result the original route-map continues or not. Apart from being useful for making import/export route-maps easier to write, this command can also be used inside any normal (in or out) route-map.

Example of Route Server Configuration¶

Finally we are going to show how to configure a FRR daemon to act as a Route Server. For this purpose we are going to present a scenario without route server, and then we will show how to use the configurations of the BGP routers to generate the configuration of the route server.

All the configuration files shown in this section have been taken from scenarios which were tested using the VNUML tool http://www.dit.upm.es/vnuml,VNUML.

Configuration of the BGP routers without Route Server¶

We will suppose that our initial scenario is an exchange point with three BGP capable routers, named RA, RB and RC. Each of the BGP speakers generates some routes (with the network command), and establishes BGP peerings against the other two routers. These peerings have In and Out route-maps configured, named like ‘PEER-X-IN’ or ‘PEER-X-OUT’. For example the configuration file for router RA could be the following:

#Configuration for router 'RA'
!
hostname RA
password ****
!
router bgp 65001
  no bgp default ipv4-unicast
  neighbor 2001:0DB8::B remote-as 65002
  neighbor 2001:0DB8::C remote-as 65003
!
  address-family ipv6
    network 2001:0DB8:AAAA:1::/64
    network 2001:0DB8:AAAA:2::/64
    network 2001:0DB8:0000:1::/64
    network 2001:0DB8:0000:2::/64
    neighbor 2001:0DB8::B activate
    neighbor 2001:0DB8::B soft-reconfiguration inbound
    neighbor 2001:0DB8::B route-map PEER-B-IN in
    neighbor 2001:0DB8::B route-map PEER-B-OUT out
    neighbor 2001:0DB8::C activate
    neighbor 2001:0DB8::C soft-reconfiguration inbound
    neighbor 2001:0DB8::C route-map PEER-C-IN in
    neighbor 2001:0DB8::C route-map PEER-C-OUT out
  exit-address-family
!
ipv6 prefix-list COMMON-PREFIXES seq  5 permit 2001:0DB8:0000::/48 ge 64 le 64
ipv6 prefix-list COMMON-PREFIXES seq 10 deny any
!
ipv6 prefix-list PEER-A-PREFIXES seq  5 permit 2001:0DB8:AAAA::/48 ge 64 le 64
ipv6 prefix-list PEER-A-PREFIXES seq 10 deny any
!
ipv6 prefix-list PEER-B-PREFIXES seq  5 permit 2001:0DB8:BBBB::/48 ge 64 le 64
ipv6 prefix-list PEER-B-PREFIXES seq 10 deny any
!
ipv6 prefix-list PEER-C-PREFIXES seq  5 permit 2001:0DB8:CCCC::/48 ge 64 le 64
ipv6 prefix-list PEER-C-PREFIXES seq 10 deny any
!
route-map PEER-B-IN permit 10
  match ipv6 address prefix-list COMMON-PREFIXES
  set metric 100
route-map PEER-B-IN permit 20
  match ipv6 address prefix-list PEER-B-PREFIXES
  set community 65001:11111
!
route-map PEER-C-IN permit 10
  match ipv6 address prefix-list COMMON-PREFIXES
  set metric 200
route-map PEER-C-IN permit 20
  match ipv6 address prefix-list PEER-C-PREFIXES
  set community 65001:22222
!
route-map PEER-B-OUT permit 10
  match ipv6 address prefix-list PEER-A-PREFIXES
!
route-map PEER-C-OUT permit 10
  match ipv6 address prefix-list PEER-A-PREFIXES
!
line vty
!

Configuration of the BGP routers with Route Server¶

To convert the initial scenario into one with route server, first we must modify the configuration of routers RA, RB and RC. Now they must not peer between them, but only with the route server. For example, RA’s configuration would turn into:

# Configuration for router 'RA'
!
hostname RA
password ****
!
router bgp 65001
  no bgp default ipv4-unicast
  neighbor 2001:0DB8::FFFF remote-as 65000
!
  address-family ipv6
    network 2001:0DB8:AAAA:1::/64
    network 2001:0DB8:AAAA:2::/64
    network 2001:0DB8:0000:1::/64
    network 2001:0DB8:0000:2::/64

    neighbor 2001:0DB8::FFFF activate
    neighbor 2001:0DB8::FFFF soft-reconfiguration inbound
  exit-address-family
!
line vty
!

Which is logically much simpler than its initial configuration, as it now maintains only one BGP peering and all the filters (route-maps) have disappeared.

Configuration of the Route Server itself¶

As we said when we described the functions of a route server (Description of the Route Server model), it is in charge of all the route filtering. To achieve that, the In and Out filters from the RA, RB and RC configurations must be converted into Import and Export policies in the route server.

This is a fragment of the route server configuration (we only show the policies for client RA):

# Configuration for Route Server ('RS')
!
hostname RS
password ix
!
router bgp 65000 view RS
  no bgp default ipv4-unicast
  neighbor 2001:0DB8::A  remote-as 65001
  neighbor 2001:0DB8::B  remote-as 65002
  neighbor 2001:0DB8::C  remote-as 65003
!
  address-family ipv6
    neighbor 2001:0DB8::A activate
    neighbor 2001:0DB8::A route-server-client
    neighbor 2001:0DB8::A route-map RSCLIENT-A-IMPORT import
    neighbor 2001:0DB8::A route-map RSCLIENT-A-EXPORT export
    neighbor 2001:0DB8::A soft-reconfiguration inbound

    neighbor 2001:0DB8::B activate
    neighbor 2001:0DB8::B route-server-client
    neighbor 2001:0DB8::B route-map RSCLIENT-B-IMPORT import
    neighbor 2001:0DB8::B route-map RSCLIENT-B-EXPORT export
    neighbor 2001:0DB8::B soft-reconfiguration inbound

    neighbor 2001:0DB8::C activate
    neighbor 2001:0DB8::C route-server-client
    neighbor 2001:0DB8::C route-map RSCLIENT-C-IMPORT import
    neighbor 2001:0DB8::C route-map RSCLIENT-C-EXPORT export
    neighbor 2001:0DB8::C soft-reconfiguration inbound
  exit-address-family
!
ipv6 prefix-list COMMON-PREFIXES seq  5 permit 2001:0DB8:0000::/48 ge 64 le 64
ipv6 prefix-list COMMON-PREFIXES seq 10 deny any
!
ipv6 prefix-list PEER-A-PREFIXES seq  5 permit 2001:0DB8:AAAA::/48 ge 64 le 64
ipv6 prefix-list PEER-A-PREFIXES seq 10 deny any
!
ipv6 prefix-list PEER-B-PREFIXES seq  5 permit 2001:0DB8:BBBB::/48 ge 64 le 64
ipv6 prefix-list PEER-B-PREFIXES seq 10 deny any
!
ipv6 prefix-list PEER-C-PREFIXES seq  5 permit 2001:0DB8:CCCC::/48 ge 64 le 64
ipv6 prefix-list PEER-C-PREFIXES seq 10 deny any
!
route-map RSCLIENT-A-IMPORT permit 10
  match peer 2001:0DB8::B
  call A-IMPORT-FROM-B
route-map RSCLIENT-A-IMPORT permit 20
  match peer 2001:0DB8::C
  call A-IMPORT-FROM-C
!
route-map A-IMPORT-FROM-B permit 10
  match ipv6 address prefix-list COMMON-PREFIXES
  set metric 100
route-map A-IMPORT-FROM-B permit 20
  match ipv6 address prefix-list PEER-B-PREFIXES
  set community 65001:11111
!
route-map A-IMPORT-FROM-C permit 10
  match ipv6 address prefix-list COMMON-PREFIXES
  set metric 200
route-map A-IMPORT-FROM-C permit 20
  match ipv6 address prefix-list PEER-C-PREFIXES
  set community 65001:22222
!
route-map RSCLIENT-A-EXPORT permit 10
  match peer 2001:0DB8::B
  match ipv6 address prefix-list PEER-A-PREFIXES
route-map RSCLIENT-A-EXPORT permit 20
  match peer 2001:0DB8::C
  match ipv6 address prefix-list PEER-A-PREFIXES
!
...
...
...

If you compare the initial configuration of RA with the route server configuration above, you can see how easy it is to generate the Import and Export policies for RA from the In and Out route-maps of RA’s original configuration.

When there was no route server, RA maintained two peerings, one with RB and another with RC. Each of this peerings had an In route-map configured. To build the Import route-map for client RA in the route server, simply add route-map entries following this scheme:

route-map <NAME> permit 10
    match peer <Peer Address>
    call <In Route-Map for this Peer>
route-map <NAME> permit 20
    match peer <Another Peer Address>
    call <In Route-Map for this Peer>

This is exactly the process that has been followed to generate the route-map RSCLIENT-A-IMPORT. The route-maps that are called inside it (A-IMPORT-FROM-B and A-IMPORT-FROM-C) are exactly the same than the In route-maps from the original configuration of RA (PEER-B-IN and PEER-C-IN), only the name is different.

The same could have been done to create the Export policy for RA (route-map RSCLIENT-A-EXPORT), but in this case the original Out route-maps where so simple that we decided not to use the call WORD commands, and we integrated all in a single route-map (RSCLIENT-A-EXPORT).

The Import and Export policies for RB and RC are not shown, but the process would be identical.

Further considerations about Import and Export route-maps¶

The current version of the route server patch only allows to specify a route-map for import and export policies, while in a standard BGP speaker apart from route-maps there are other tools for performing input and output filtering (access-lists, community-lists, …). But this does not represent any limitation, as all kinds of filters can be included in import/export route-maps. For example suppose that in the non-route-server scenario peer RA had the following filters configured for input from peer B:

neighbor 2001:0DB8::B prefix-list LIST-1 in
neighbor 2001:0DB8::B filter-list LIST-2 in
neighbor 2001:0DB8::B route-map PEER-B-IN in
...
...
route-map PEER-B-IN permit 10
  match ipv6 address prefix-list COMMON-PREFIXES
  set local-preference 100
route-map PEER-B-IN permit 20
  match ipv6 address prefix-list PEER-B-PREFIXES
  set community 65001:11111

It is possible to write a single route-map which is equivalent to the three filters (the community-list, the prefix-list and the route-map). That route-map can then be used inside the Import policy in the route server. Lets see how to do it:

neighbor 2001:0DB8::A route-map RSCLIENT-A-IMPORT import
...
!
...
route-map RSCLIENT-A-IMPORT permit 10
  match peer 2001:0DB8::B
  call A-IMPORT-FROM-B
...
...
!
route-map A-IMPORT-FROM-B permit 1
  match ipv6 address prefix-list LIST-1
  match as-path LIST-2
  on-match goto 10
route-map A-IMPORT-FROM-B deny 2
route-map A-IMPORT-FROM-B permit 10
  match ipv6 address prefix-list COMMON-PREFIXES
  set local-preference 100
route-map A-IMPORT-FROM-B permit 20
  match ipv6 address prefix-list PEER-B-PREFIXES
  set community 65001:11111
!
...
...

The route-map A-IMPORT-FROM-B is equivalent to the three filters (LIST-1, LIST-2 and PEER-B-IN). The first entry of route-map A-IMPORT-FROM-B (sequence number 1) matches if and only if both the prefix-list LIST-1 and the filter-list LIST-2 match. If that happens, due to the ‘on-match goto 10’ statement the next route-map entry to be processed will be number 10, and as of that point route-map A-IMPORT-FROM-B is identical to PEER-B-IN. If the first entry does not match, on-match goto 10’ will be ignored and the next processed entry will be number 2, which will deny the route.

Thus, the result is the same that with the three original filters, i.e., if either LIST-1 or LIST-2 rejects the route, it does not reach the route-map PEER-B-IN. In case both LIST-1 and LIST-2 accept the route, it passes to PEER-B-IN, which can reject, accept or modify the route.

Prefix Origin Validation Using RPKI¶

Prefix Origin Validation allows BGP routers to verify if the origin AS of an IP prefix is legitimate to announce this IP prefix. The required attestation objects are stored in the Resource Public Key Infrastructure (RPKI). However, RPKI-enabled routers do not store cryptographic data itself but only validation information. The validation of the cryptographic data (so called Route Origin Authorization, or short ROA, objects) will be performed by trusted cache servers. The RPKI/RTR protocol defines a standard mechanism to maintain the exchange of the prefix/origin AS mapping between the cache server and routers. In combination with a BGP Prefix Origin Validation scheme a router is able to verify received BGP updates without suffering from cryptographic complexity.

The RPKI/RTR protocol is defined in RFC 6810 and the validation scheme in RFC 6811. The current version of Prefix Origin Validation in FRR implements both RFCs.

For a more detailed but still easy-to-read background, we suggest:

Features of the Current Implementation¶

In a nutshell, the current implementation provides the following features

The BGP router can connect to one or more RPKI cache servers to receive validated prefix to origin AS mappings. Advanced failover can be implemented by server sockets with different preference values.
If no connection to an RPKI cache server can be established after a pre-defined timeout, the router will process routes without prefix origin validation. It still will try to establish a connection to an RPKI cache server in the background.
By default, enabling RPKI does not change best path selection. In particular, invalid prefixes will still be considered during best path selection. However, the router can be configured to ignore all invalid prefixes.
Route maps can be configured to match a specific RPKI validation state. This allows the creation of local policies, which handle BGP routes based on the outcome of the Prefix Origin Validation.
Updates from the RPKI cache servers are directly applied and path selection is updated accordingly. (Soft reconfiguration must be enabled for this to work).

Enabling RPKI¶

rpki¶

This command enables the RPKI configuration mode. Most commands that start with rpki can only be used in this mode.

When it is used in a telnet session, leaving of this mode cause rpki to be initialized.

Executing this command alone does not activate prefix validation. You need to configure at least one reachable cache server. See section Configuring RPKI/RTR Cache Servers for configuring a cache server.

When first installing FRR with RPKI support from the pre-packaged binaries. Remember to add -M rpki to the variable bgpd_options in /etc/frr/daemons , like so:

bgpd_options="   -A 127.0.0.1 -M rpki"

instead of the default setting:

bgpd_options="   -A 127.0.0.1"

Otherwise you will encounter an error when trying to enter RPKI configuration mode due to the rpki module not being loaded when the BGP daemon is initialized.

Examples of the error:

router(config)# debug rpki
% [BGP] Unknown command: debug rpki

router(config)# rpki
% [BGP] Unknown command: rpki

Note that the RPKI commands will be available in vtysh when running find rpki regardless of whether the module is loaded.

Configuring RPKI/RTR Cache Servers¶

The following commands are independent of a specific cache server.

rpki polling_period (1-3600)¶

no rpki polling_period¶

Set the number of seconds the router waits until the router asks the cache again for updated data.

The default value is 300 seconds.

The following commands configure one or multiple cache servers.

rpki cache (A.B.C.D|WORD) PORT [SSH_USERNAME] [SSH_PRIVKEY_PATH] [SSH_PUBKEY_PATH] [KNOWN_HOSTS_PATH] PREFERENCE¶

no rpki cache (A.B.C.D|WORD) [PORT] PREFERENCE¶

Add a cache server to the socket. By default, the connection between router and cache server is based on plain TCP. Protecting the connection between router and cache server by SSH is optional. Deleting a socket removes the associated cache server and terminates the existing connection.

A.B.C.D|WORD: Address of the cache server.
PORT: Port number to connect to the cache server
SSH_USERNAME: SSH username to establish an SSH connection to the cache server.
SSH_PRIVKEY_PATH: Local path that includes the private key file of the router.
SSH_PUBKEY_PATH: Local path that includes the public key file of the router.
KNOWN_HOSTS_PATH: Local path that includes the known hosts file. The default value depends on the configuration of the operating system environment, usually ~/.ssh/known_hosts.

Validating BGP Updates¶

match rpki notfound|invalid|valid¶

no match rpki notfound|invalid|valid¶

Create a clause for a route map to match prefixes with the specified RPKI state.

In the following example, the router prefers valid routes over invalid prefixes because invalid routes have a lower local preference.

! Allow for invalid routes in route selection process
route bgp 60001
!
! Set local preference of invalid prefixes to 10
route-map rpki permit 10
 match rpki invalid
 set local-preference 10
!
! Set local preference of valid prefixes to 500
route-map rpki permit 500
 match rpki valid
 set local-preference 500

Debugging¶

debug rpki¶

no debug rpki¶: Enable or disable debugging output for RPKI.

Displaying RPKI¶

show rpki prefix-table¶: Display all validated prefix to origin AS mappings/records which have been received from the cache servers and stored in the router. Based on this data, the router validates BGP Updates.

show rpki cache-connection¶: Display all configured cache servers, whether active or not.

RPKI Configuration Example¶

hostname bgpd1
password zebra
! log stdout
debug bgp updates
debug bgp keepalives
debug rpki
!
rpki
 rpki polling_period 1000
 rpki timeout 10
  ! SSH Example:
  rpki cache example.com 22 rtr-ssh ./ssh_key/id_rsa ./ssh_key/id_rsa.pub preference 1
  ! TCP Example:
  rpki cache rpki-validator.realmv6.org 8282 preference 2
  exit
!
router bgp 60001
 bgp router-id 141.22.28.223
 network 192.168.0.0/16
 neighbor 123.123.123.0 remote-as 60002
 neighbor 123.123.123.0 route-map rpki in
!
 address-family ipv6
  neighbor 123.123.123.0 activate
   neighbor 123.123.123.0 route-map rpki in
 exit-address-family
!
route-map rpki permit 10
 match rpki invalid
 set local-preference 10
!
route-map rpki permit 20
 match rpki notfound
 set local-preference 20
!
route-map rpki permit 30
 match rpki valid
 set local-preference 30
!
route-map rpki permit 40
!

[Securing-BGP]

Geoff Huston, Randy Bush: Securing BGP, In: The Internet Protocol Journal, Volume 14, No. 2, 2011. <http://www.cisco.com/web/about/ac123/ac147/archived_issues/ipj_14-2/142_bgp.html>

[Resource-Certification]

Geoff Huston: Resource Certification, In: The Internet Protocol Journal, Volume 12, No.1, 2009. <http://www.cisco.com/web/about/ac123/ac147/archived_issues/ipj_12-1/121_resource.html>

Flowspec¶

Overview¶

Flowspec introduces a new NLRI encoding format that is used to distribute traffic rule flow specifications. Basically, instead of simply relying on destination IP address for IP prefixes, the IP prefix is replaced by a n-tuple consisting of a rule. That rule can be a more or less complex combination of the following:

Network source/destination (can be one or the other, or both).
Layer 4 information for UDP/TCP: source port, destination port, or any port.
Layer 4 information for ICMP type and ICMP code.
Layer 4 information for TCP Flags.
Layer 3 information: DSCP value, Protocol type, packet length, fragmentation.
Misc layer 4 TCP flags.

A combination of the above rules is applied for traffic filtering. This is encoded as part of specific BGP extended communities and the action can range from the obvious rerouting (to nexthop or to separate VRF) to shaping, or discard.

The following IETF drafts and RFCs have been used to implement FRR Flowspec:

Design Principles¶

FRR implements the Flowspec client side, that is to say that BGP is able to receive Flowspec entries, but is not able to act as manager and send Flowspec entries.

Linux provides the following mechanisms to implement policy based routing:

Filtering the traffic with Netfilter. Netfilter provides a set of tools like ipset and iptables that are powerful enough to be able to filter such Flowspec filter rule.
using non standard routing tables via iproute2 (via the ip rule command provided by iproute2). iproute2 is already used by FRR’s PBR daemon which provides basic policy based routing based on IP source and destination criterion.

Below example is an illustration of what Flowspec will inject in the underlying system:

# linux shell
ipset create match0x102 hash:net,net counters
ipset add match0x102 32.0.0.0/16,40.0.0.0/16
iptables -N match0x102 -t mangle
iptables -A match0x102 -t mangle -j MARK --set-mark 102
iptables -A match0x102 -t mangle -j ACCEPT
iptables -i ntfp3 -t mangle -I PREROUTING -m set --match-set match0x102
             src,dst -g match0x102
ip rule add fwmark 102 lookup 102
ip route add 40.0.0.0/16 via 44.0.0.2 table 102

For handling an incoming Flowspec entry, the following workflow is applied:

Incoming Flowspec entries are handled by bgpd, stored in the BGP RIB.
Flowspec entry is installed according to its complexity.

It will be installed if one of the following filtering action is seen on the BGP extended community: either redirect IP, or redirect VRF, in conjunction with rate option, for redirecting traffic. Or rate option set to 0, for discarding traffic.

According to the degree of complexity of the Flowspec entry, it will be installed in zebra RIB. For more information about what is supported in the FRR implementation as rule, see Limitations / Known Issues chapter. Flowspec entry is split in several parts before being sent to zebra.

zebra daemon receives the policy routing configuration

Policy Based Routing entities necessary to policy route the traffic in the underlying system, are received by zebra. Two filtering contexts will be created or appended in Netfilter: ipset and iptable context. The former is used to define an IP filter based on multiple criterium. For instance, an ipset net:net is based on two ip addresses, while net,port,net is based on two ip addresses and one port (for ICMP, UDP, or TCP). The way the filtering is used (for example, is src port or dst port used?) is defined by the latter filtering context. iptable command will reference the ipset context and will tell how to filter and what to do. In our case, a marker will be set to indicate iproute2 where to forward the traffic to. Sometimes, for dropping action, there is no need to add a marker; the iptable will tell to drop all packets matching the ipset entry.

Configuration Guide¶

In order to configure an IPv4 Flowspec engine, use the following configuration. As of today, it is only possible to configure Flowspec on the default VRF.

router bgp <AS>
  neighbor <A.B.C.D> remote-as <remoteAS>
  address-family ipv4 flowspec
   neighbor <A.B.C.D> activate
 exit
exit

You can see Flowspec entries, by using one of the following show commands:

show bgp ipv4 flowspec [detail | A.B.C.D]¶

Per-interface configuration¶

One nice feature to use is the ability to apply Flowspec to a specific interface, instead of applying it to the whole machine. Despite the following IETF draft [Draft-IETF-IDR-Flowspec-Interface-Set] is not implemented, it is possible to manually limit Flowspec application to some incoming interfaces. Actually, not using it can result to some unexpected behaviour like accounting twice the traffic, or slow down the traffic (filtering costs). To limit Flowspec to one specific interface, use the following command, under flowspec address-family node.

[no] local-install <IFNAME | any>¶

By default, Flowspec is activated on all interfaces. Installing it to a named interface will result in allowing only this interface. Conversely, enabling any interface will flush all previously configured interfaces.

VRF redirection¶

Another nice feature to configure is the ability to redirect traffic to a separate VRF. This feature does not go against the ability to configure Flowspec only on default VRF. Actually, when you receive incoming BGP flowspec entries on that default VRF, you can redirect traffic to an other VRF.

As a reminder, BGP flowspec entries have a BGP extended community that contains a Route Target. Finding out a local VRF based on Route Target consists in the following:

A configuration of each VRF must be done, with its Route Target set Each VRF is being configured within a BGP VRF instance with its own Route Target list. Route Target accepted format matches the following: A.B.C.D:U16, or U16:U32, U32:U16.
The first VRF with the matching Route Target will be selected to route traffic to. Use the following command under ipv4 unicast address-family node

[no] rt redirect import RTLIST...¶

In order to illustrate, if the Route Target configured in the Flowspec entry is E.F.G.H:II, then a BGP VRF instance with the same Route Target will be set set. That VRF will then be selected. The below full configuration example depicts how Route Targets are configured and how VRFs and cross VRF configuration is done. Note that the VRF are mapped on Linux Network Namespaces. For data traffic to cross VRF boundaries, virtual ethernet interfaces are created with private IP addressing scheme.

router bgp <ASx>
 neighbor <A.B.C.D> remote-as <ASz>
 address-family ipv4 flowspec
  neighbor A.B.C.D activate
 exit
exit
router bgp <ASy> vrf vrf2
 address-family ipv4 unicast
  rt redirect import <E.F.G.H:II>
 exit
exit

Flowspec monitoring & troubleshooting¶

You can monitor policy-routing objects by using one of the following commands. Those command rely on the filtering contexts configured from BGP, and get the statistics information retrieved from the underlying system. In other words, those statistics are retrieved from Netfilter.

show pbr ipset IPSETNAME | iptable¶

IPSETNAME is the policy routing object name created by ipset. About rule contexts, it is possible to know which rule has been configured to policy-route some specific traffic. The show pbr iptable command displays for forwarded traffic, which table is used. Then it is easy to use that table identifier to dump the routing table that the forwarded traffic will match.

show ip route table TABLEID¶: TABLEID is the table number identifier referencing the non standard routing table used in this example.

[no] debug bgp flowspec¶: You can troubleshoot Flowspec, or BGP policy based routing. For instance, if you encounter some issues when decoding a Flowspec entry, you should enable debug bgp flowspec.

[no] debug bgp pbr [error]¶

If you fail to apply the flowspec entry into zebra, there should be some relationship with policy routing mechanism. Here, debug bgp pbr error could help.

To get information about policy routing contexts created/removed, only use debug bgp pbr command.

Ensuring that a Flowspec entry has been correctly installed and that incoming traffic is policy-routed correctly can be checked as demonstrated below. First of all, you must check whether the Flowspec entry has been installed or not.

CLI# show bgp ipv4 flowspec 5.5.5.2/32
 BGP flowspec entry: (flags 0x418)
   Destination Address 5.5.5.2/32
   IP Protocol = 17
   Destination Port >= 50 , <= 90
   FS:redirect VRF RT:255.255.255.255:255
   received for 18:41:37
   installed in PBR (match0x271ce00)

This means that the Flowspec entry has been installed in an iptable named match0x271ce00. Once you have confirmation it is installed, you can check whether you find the associate entry by executing following command. You can also check whether incoming traffic has been matched by looking at counter line.

CLI# show pbr ipset match0x271ce00
IPset match0x271ce00 type net,port
     to 5.5.5.0/24:proto 6:80-120 (8)
        pkts 1000, bytes 1000000
     to 5.5.5.2:proto 17:50-90 (5)
        pkts 1692918, bytes 157441374

As you can see, the entry is present. note that an iptable entry can be used to host several Flowspec entries. In order to know where the matching traffic is redirected to, you have to look at the policy routing rules. The policy-routing is done by forwarding traffic to a routing table number. That routing table number is reached by using a iptable. The relationship between the routing table number and the incoming traffic is a MARKER that is set by the IPtable referencing the IPSet. In Flowspec case, iptable referencing the ipset context have the same name. So it is easy to know which routing table is used by issuing following command:

CLI# show pbr iptable
   IPtable match0x271ce00 action redirect (5)
     pkts 1700000, bytes 158000000
     table 257, fwmark 257
...

As you can see, by using following Linux commands, the MARKER 0x101 is present in both iptable and ip rule contexts.

# iptables -t mangle --list match0x271ce00 -v
Chain match0x271ce00 (1 references)
pkts bytes target     prot opt in     out     source              destination
1700K  158M MARK       all  --  any    any     anywhere             anywhere
     MARK set 0x101
1700K  158M ACCEPT     all  --  any    any     anywhere             anywhere

# ip rule list
0:from all lookup local
0:from all fwmark 0x101 lookup 257
32766:from all lookup main
32767:from all lookup default

This allows us to see where the traffic is forwarded to.

Limitations / Known Issues¶

As you can see, Flowspec is rich and can be very complex. As of today, not all Flowspec rules will be able to be converted into Policy Based Routing actions.

The Netfilter driver is not integrated into FRR yet. Not having this piece of code prevents from injecting flowspec entries into the underlying system.
There are some limitations around filtering contexts

If I take example of UDP ports, or TCP ports in Flowspec, the information can be a range of ports, or a unique value. This case is handled. However, complexity can be increased, if the flow is a combination of a list of range of ports and an enumerate of unique values. Here this case is not handled. Similarly, it is not possible to create a filter for both src port and dst port. For instance, filter on src port from [1-1000] and dst port = 80. The same kind of complexity is not possible for packet length, ICMP type, ICMP code.

There are some other known issues:

The validation procedure depicted in RFC 5575 is not available.

This validation procedure has not been implemented, as this feature was not used in the existing setups you shared with us.
The filtering action shaper value, if positive, is not used to apply shaping.

If value is positive, the traffic is redirected to the wished destination, without any other action configured by Flowspec. It is recommended to configure Quality of Service if needed, more globally on a per interface basis.
Upon an unexpected crash or other event, zebra may not have time to flush PBR contexts.

That is to say ipset, iptable and ip rule contexts. This is also a consequence due to the fact that ip rule / ipset / iptables are not discovered at startup (not able to read appropriate contexts coming from Flowspec).

Appendix¶

More information with a public presentation that explains the design of Flowspec inside FRRouting.

[Presentation]

[Draft-IETF-IDR-Flowspec-redirect-IP]

<https://tools.ietf.org/id/draft-ietf-idr-flowspec-redirect-ip-02.txt>

[Draft-IETF-IDR-Flowspec-Interface-Set]

<https://tools.ietf.org/id/draft-ietf-idr-flowspec-interfaceset-03.txt>

[Presentation]

<https://docs.google.com/presentation/d/1ekQygUAG5yvQ3wWUyrw4Wcag0LgmbW1kV02IWcU4iUg/edit#slide=id.g378f0e1b5e_1_44>

[1]

For some set of objects to have an order, there must be some binary ordering relation that is defined for every combination of those objects, and that relation must be transitive. I.e.:, if the relation operator is <, and if a < b and b < c then that relation must carry over and it must be that a < c for the objects to have an order. The ordering relation may allow for equality, i.e. a < b and b < a may both be true and imply that a and b are equal in the order and not distinguished by it, in which case the set has a partial order. Otherwise, if there is an order, all the objects have a distinct place in the order and the set has a total order)

[bgp-route-osci-cond]

McPherson, D. and Gill, V. and Walton, D., “Border Gateway Protocol (BGP) Persistent Route Oscillation Condition”, IETF RFC3345

[stable-flexible-ibgp]

Flavel, A. and M. Roughan, “Stable and flexible iBGP”, ACM SIGCOMM 2009

[ibgp-correctness]

Griffin, T. and G. Wilfong, “On the correctness of IBGP configuration”, ACM SIGCOMM 2002

Babel¶

Babel is an interior gateway protocol that is suitable both for wired networks and for wireless mesh networks. Babel has been described as ‘RIP on speed’ – it is based on the same principles as RIP, but includes a number of refinements that make it react much faster to topology changes without ever counting to infinity, and allow it to perform reliable link quality estimation on wireless links. Babel is a double-stack routing protocol, meaning that a single Babel instance is able to perform routing for both IPv4 and IPv6.

FRR implements Babel as described in RFC 6126.

Configuring babeld¶

The babeld daemon can be invoked with any of the common options (Common Invocation Options).

The zebra daemon must be running before babeld is invoked. Also, if zebra is restarted then babeld must be too.

Configuration of babeld is done in its configuration file babeld.conf.

Babel configuration¶

[no] router babel¶: Enable or disable Babel routing.

[no] babel resend-delay (20-655340)¶: Specifies the time after which important messages are resent when avoiding a black-hole. The default is 2000 ms.

[no] babel diversity¶: Enable or disable routing using radio frequency diversity. This is highly recommended in networks with many wireless nodes. If you enable this, you will probably want to set babel diversity-factor and babel channel below.

babel diversity-factor (1-256)¶: Sets the multiplicative factor used for diversity routing, in units of 1/256; lower values cause diversity to play a more important role in route selection. The default it 256, which means that diversity plays no role in route selection; you will probably want to set that to 128 or less on nodes with multiple independent radios.

no network IFNAME¶: Enable or disable Babel on the given interface.

babel <wired|wireless>¶: Specifies whether this interface is wireless, which disables a number of optimisations that are only correct on wired interfaces. Specifying wireless (the default) is always correct, but may cause slower convergence and extra routing traffic.

[no] babel split-horizon¶: Specifies whether to perform split-horizon on the interface. Specifying no babel split-horizon is always correct, while babel split-horizon is an optimisation that should only be used on symmetric and transitive (wired) networks. The default is babel split-horizon on wired interfaces, and no babel split-horizon on wireless interfaces. This flag is reset when the wired/wireless status of an interface is changed.

babel hello-interval (20-655340)¶: Specifies the time in milliseconds between two scheduled hellos. On wired links, Babel notices a link failure within two hello intervals; on wireless links, the link quality value is reestimated at every hello interval. The default is 4000 ms.

babel update-interval (20-655340)¶: Specifies the time in milliseconds between two scheduled updates. Since Babel makes extensive use of triggered updates, this can be set to fairly high values on links with little packet loss. The default is 20000 ms.

babel channel (1-254)¶

babel channel interfering¶

babel channel noninterfering¶: Set the channel number that diversity routing uses for this interface (see babel diversity above). Noninterfering interfaces are assumed to only interfere with themselves, interfering interfaces are assumed to interfere with all other channels except noninterfering channels, and interfaces with a channel number interfere with interfering interfaces and interfaces with the same channel number. The default is babel channel interfering for wireless interfaces, and babel channel noninterfering for wired interfaces. This is reset when the wired/wireless status of an interface is changed.

babel rxcost (1-65534)¶: Specifies the base receive cost for this interface. For wireless interfaces, it specifies the multiplier used for computing the ETX reception cost (default 256); for wired interfaces, it specifies the cost that will be advertised to neighbours. This value is reset when the wired/wireless attribute of the interface is changed.

Note

Do not use this command unless you know what you are doing; in most networks, acting directly on the cost using route maps is a better technique.

babel rtt-decay (1-256)¶: This specifies the decay factor for the exponential moving average of RTT samples, in units of 1/256. Higher values discard old samples faster. The default is 42.

babel rtt-min (1-65535)¶: This specifies the minimum RTT, in milliseconds, starting from which we increase the cost to a neighbour. The additional cost is linear in (rtt - rtt-min). The default is 100 ms.

babel rtt-max (1-65535)¶: This specifies the maximum RTT, in milliseconds, above which we don’t increase the cost to a neighbour. The default is 120 ms.

babel max-rtt-penalty (0-65535)¶: This specifies the maximum cost added to a neighbour because of RTT, i.e. when the RTT is higher or equal than rtt-max. The default is 0, which effectively disables the use of a RTT-based cost.

[no] babel enable-timestamps¶: Enable or disable sending timestamps with each Hello and IHU message in order to compute RTT values. The default is no babel enable-timestamps.

babel resend-delay (20-655340)¶: Specifies the time in milliseconds after which an ‘important’ request or update will be resent. The default is 2000 ms. You probably don’t want to tweak this value.

babel smoothing-half-life (0-65534)¶: Specifies the time constant, in seconds, of the smoothing algorithm used for implementing hysteresis. Larger values reduce route oscillation at the cost of very slightly increasing convergence time. The value 0 disables hysteresis, and is suitable for wired networks. The default is 4 s.

Babel redistribution¶

[no] redistribute <ipv4|ipv6> KIND¶: Specify which kind of routes should be redistributed into Babel.

Show Babel information¶

These commands dump various parts of babeld’s internal state.

show babel route¶

show babel route A.B.C.D¶

show babel route X:X::X:X¶

show babel route A.B.C.D/M¶

show babel route X:X::X:X/M¶

show babel interface¶

show babel interface IFNAME¶

show babel neighbor¶

show babel parameters¶

Babel debugging commands¶

[no] debug babel KIND¶

Enable or disable debugging messages of a given kind. KIND can be one of:

common
filter
timeout
interface
route
all

Note

If you have compiled with the NO_DEBUG flag, then these commands aren’t available.

OpenFabric¶

OpenFabric, specified in draft-white-openfabric-06.txt, is a routing protocol derived from IS-IS, providing link-state routing with efficient flooding for topologies like spine-leaf networks.

FRR implements OpenFabric in a daemon called fabricd

Configuring fabricd¶

There are no fabricd specific options. Common options can be specified (Common Invocation Options) to fabricd. fabricd needs to acquire interface information from zebra in order to function. Therefore zebra must be running before invoking fabricd. Also, if zebra is restarted then fabricd must be too.

Like other daemons, fabricd configuration is done in an OpenFabric specific configuration file fabricd.conf.

OpenFabric router¶

To enable the OpenFabric routing protocol, an OpenFabric router needs to be created in the configuration:

router openfabric WORD¶

no router openfabric WORD¶: Enable or disable the OpenFabric process by specifying the OpenFabric domain with ‘WORD’.

net XX.XXXX. ... .XXX.XX¶

no net XX.XXXX. ... .XXX.XX¶: Set/Unset network entity title (NET) provided in ISO format.

domain-password [clear | md5] <password>¶

no domain-password¶: Configure the authentication password for a domain, as clear text or md5 one.

log-adjacency-changes¶

no log-adjacency-changes¶: Log changes in adjacency state.

set-overload-bit¶

no set-overload-bit¶: Set overload bit to avoid any transit traffic.

purge-originator¶

no purge-originator¶: Enable or disable RFC 6232 purge originator identification.

fabric-tier (0-14)¶

no fabric-tier¶: Configure a static tier number to advertise as location in the fabric

OpenFabric Timer¶

lsp-gen-interval (1-120)¶

no lsp-gen-interval¶: Set minimum interval in seconds between regenerating same LSP.

lsp-refresh-interval (1-65235)¶

no lsp-refresh-interval¶: Set LSP refresh interval in seconds.

max-lsp-lifetime (360-65535)¶

no max-lsp-lifetime¶: Set LSP maximum LSP lifetime in seconds.

spf-interval (1-120)¶

no spf-interval¶: Set minimum interval between consecutive SPF calculations in seconds.

OpenFabric interface¶

ip router openfabric WORD¶

no ip router openfabric WORD¶

Activate OpenFabric on this interface. Note that the name of OpenFabric instance must be the same as the one used to configure the routing process (see command router openfabric WORD).

openfabric csnp-interval (1-600)¶

no openfabric csnp-interval¶: Set CSNP interval in seconds.

openfabric hello-interval (1-600)¶

no openfabric hello-interval¶: Set Hello interval in seconds.

openfabric hello-multiplier (2-100)¶

no openfabric hello-multiplier¶: Set multiplier for Hello holding time.

openfabric metric (0-16777215)¶

no openfabric metric¶: Set interface metric value.

openfabric passive¶

no openfabric passive¶: Configure the passive mode for this interface.

openfabric password [clear | md5] <password>¶

no openfabric password¶: Configure the authentication password (clear or encoded text) for the interface.

openfabric psnp-interval (1-120)¶

no openfabric psnp-interval¶: Set PSNP interval in seconds.

Showing OpenFabric information¶

show openfabric summary¶: Show summary information about OpenFabric.

show openfabric hostname¶: Show which hostnames are associated with which OpenFabric system ids.

show openfabric interface¶

show openfabric interface detail¶

show openfabric interface <interface name>¶: Show state and configuration of specified OpenFabric interface, or all interfaces if no interface is given with or without details.

show openfabric neighbor¶

show openfabric neighbor <System Id>¶

show openfabric neighbor detail¶: Show state and information of specified OpenFabric neighbor, or all neighbors if no system id is given with or without details.

show openfabric database¶

show openfabric database [detail]¶

show openfabric database <LSP id> [detail]¶

show openfabric database detail <LSP id>¶: Show the OpenFabric database globally, for a specific LSP id without or with details.

show openfabric topology¶: Show calculated OpenFabric paths and associated topology information.

Debugging OpenFabric¶

debug openfabric adj-packets¶

no debug openfabric adj-packets¶

OpenFabric Adjacency related packets.

debug openfabric checksum-errors¶

no debug openfabric checksum-errors¶

OpenFabric LSP checksum errors.

debug openfabric events¶

no debug openfabric events¶

OpenFabric Events.

debug openfabric local-updates¶

no debug openfabric local-updates¶

OpenFabric local update packets.

debug openfabric lsp-gen¶

no debug openfabric lsp-gen¶

Generation of own LSPs.

debug openfabric lsp-sched¶

no debug openfabric lsp-sched¶

Debug scheduling of generation of own LSPs.

debug openfabric packet-dump¶

no debug openfabric packet-dump¶

OpenFabric packet dump.

debug openfabric protocol-errors¶

no debug openfabric protocol-errors¶

OpenFabric LSP protocol errors.

debug openfabric route-events¶

no debug openfabric route-events¶

OpenFabric Route related events.

debug openfabric snp-packets¶

no debug openfabric snp-packets¶

OpenFabric CSNP/PSNP packets.

debug openfabric spf-events¶

debug openfabric spf-statistics¶

debug openfabric spf-triggers¶

no debug openfabric spf-events¶

no debug openfabric spf-statistics¶

no debug openfabric spf-triggers¶

OpenFabric Shortest Path First Events, Timing and Statistic Data and triggering events.

debug openfabric update-packets¶

no debug openfabric update-packets¶

Update related packets.

show debugging openfabric¶: Print which OpenFabric debug levels are active.

OpenFabric configuration example¶

A simple example:

!
interface lo
 ip address 192.0.2.1/32
 ip router openfabric 1
 ipv6 address 2001:db8::1/128
 ipv6 router openfabric 1
!
interface eth0
 ip router openfabric 1
 ipv6 router openfabric 1
!
interface eth1
 ip router openfabric 1
 ipv6 router openfabric 1
!
router openfabric 1
 net 49.0000.0000.0001.00

LDP¶

The ldpd daemon is a standardised protocol that permits exchanging MPLS label information between MPLS devices. The LDP protocol creates peering between devices, so as to exchange that label information. This information is stored in MPLS table of zebra, and it injects that MPLS information in the underlying system (Linux kernel or OpenBSD system for instance). ldpd provides necessary options to create a Layer 2 VPN across MPLS network. For instance, it is possible to interconnect several sites that share the same broadcast domain.

FRR implements LDP as described in RFC 5036; other LDP standard are the following ones: RFC 6720, RFC 6667, RFC 5919, RFC 5561, RFC 7552, RFC 4447. Because MPLS is already available, FRR also supports RFC 3031.

Running Ldpd¶

The ldpd daemon can be invoked with any of the common options (Common Invocation Options).

..option:: –ctl_socket

This option allows you to override the path to the ldpd.sock file used to control this daemon. If specified this option overrides the -N option path addition.

The zebra daemon must be running before ldpd is invoked.

Configuration of ldpd is done in its configuration file ldpd.conf.

Understanding LDP principles¶

Let’s first introduce some definitions that permit understand better the LDP protocol:

LSR : Labeled Switch Router. Networking devices handling labels used to forward traffic between and through them.
LER : Labeled Edge Router. A Labeled edge router is located at the edge of

an MPLS network, generally between an IP network and an MPLS network.

LDP aims at sharing label information across devices. It tries to establish peering with remote LDP capable devices, first by discovering using UDP port 646 , then by peering using TCP port 646. Once the TCP session is established, the label information is shared, through label advertisements.

There are different methods to send label advertisement modes. The implementation actually supports the following : Liberal Label Retention + Downstream Unsolicited + Independent Control. The other advertising modes are depicted below, and compared with the current implementation.

Liberal label retention versus conservative mode In liberal mode, every label sent by every LSR is stored in the MPLS table. In conservative mode, only the label that was sent by the best next hop (determined by the IGP metric) for that particular FEC is stored in the MPLS table.
Independent LSP Control versus ordered LSP Control MPLS has two ways of binding labels to FEC’s; either through ordered LSP control, or independent LSP control. Ordered LSP control only binds a label to a FEC if it is the egress LSR, or the router received a label binding for a FEC from the next hop router. In this mode, an MPLS router will create a label binding for each FEC and distribute it to its neighbors so long as he has a entry in the RIB for the destination. In the other mode, label bindings are made without any dependencies on another router advertising a label for a particular FEC. Each router makes it own independent decision to create a label for each FEC. By default IOS uses Independent LSP Control, while Juniper implements the Ordered Control. Both modes are interoperable, the difference is that Ordered Control prevent blackholing during the LDP convergence process, at cost of slowing down the convergence itself
unsolicited downstream versus downstream on demand Downstream on demand label distribution is where an LSR must explicitly request that a label be sent from its downstream router for a particular FEC. Unsolicited label distribution is where a label is sent from the downstream router without the original router requesting it.

LDP Configuration¶

[no] mpls ldp¶: Enable or disable LDP daemon

[no] router-id A.B.C.D¶: The following command located under MPLS router node configures the MPLS router-id of the local device.

[no] address-family [ipv4 | ipv6]¶: Configure LDP for IPv4 or IPv6 address-family. Located under MPLS route node, this subnode permits configuring the LDP neighbors.

[no] interface IFACE¶: Located under MPLS address-family node, use this command to enable or disable LDP discovery per interface. IFACE stands for the interface name where LDP is enabled. By default it is disabled. Once this command executed, the address-family interface node is configured.

[no] discovery transport-address A.B.C.D | A:B::C:D¶: Located under mpls address-family interface node, use this command to set the IPv4 or IPv6 transport-address used by the LDP protocol to talk on this interface.

[no] neighbor A.B.C.D password PASSWORD¶: The following command located under MPLS router node configures the router of a LDP device. This device, if found, will have to comply with the configured password. PASSWORD is a clear text password wit its digest sent through the network.

[no] neighbor A.B.C.D holdtime HOLDTIME¶: The following command located under MPLS router node configures the holdtime value in seconds of the LDP neighbor ID. Configuring it triggers a keepalive mechanism. That value can be configured between 15 and 65535 seconds. After this time of non response, the LDP established session will be considered as set to down. By default, no holdtime is configured for the LDP devices.

[no] discovery hello holdtime HOLDTIME¶

[no] discovery hello interval INTERVAL¶: INTERVAL value ranges from 1 to 65535 seconds. Default value is 5 seconds. This is the value between each hello timer message sent. HOLDTIME value ranges from 1 to 65535 seconds. Default value is 15 seconds. That value is added as a TLV in the LDP messages.

[no] dual-stack transport-connection prefer ipv4¶: When ldpd is configured for dual-stack operation, the transport connection preference is IPv6 by default (as specified by RFC 7552). On such circumstances, ldpd will refuse to establish TCP connections over IPv4. You can use above command to change the transport connection preference to IPv4. In this case, it will be possible to distribute label mappings for IPv6 FECs over TCPv4 connections.

Show LDP Information¶

These commands dump various parts of ldpd.

show mpls ldp neighbor [A.B.C.D]¶

This command dumps the various neighbors discovered. Below example shows that local machine has an operation neighbor with ID set to 1.1.1.1.

west-vm# show mpls ldp neighbor
AF   ID              State       Remote Address    Uptime
ipv4 1.1.1.1         OPERATIONAL 1.1.1.1         00:01:37
west-vm#

show mpls ldp neighbor [A.B.C.D] capabilities¶

show mpls ldp neighbor [A.B.C.D] detail¶: Above commands dump other neighbor information.

show mpls ldp discovery [detail]¶

show mpls ldp ipv4 discovery [detail]¶

show mpls ldp ipv6 discovery [detail]¶: Above commands dump discovery information.

show mpls ldp ipv4 interface¶

show mpls ldp ipv6 interface¶

Above command dumps the IPv4 or IPv6 interface per where LDP is enabled. Below output illustrates what is dumped for IPv4.

west-vm# show mpls ldp ipv4 interface
AF   Interface   State  Uptime   Hello Timers  ac
ipv4 eth1       ACTIVE 00:08:35 5/15           0
ipv4 eth3       ACTIVE 00:08:35 5/15           1

show mpls ldp ipv4|ipv6 binding¶

Above command dumps the binding obtained through MPLS exchanges with LDP.

west-vm# show mpls ldp ipv4 binding
AF   Destination          Nexthop         Local Label Remote Label  In Use
ipv4 1.1.1.1/32           1.1.1.1         16          imp-null         yes
ipv4 2.2.2.2/32           1.1.1.1         imp-null    16                no
ipv4 10.0.2.0/24          1.1.1.1         imp-null    imp-null          no
ipv4 10.115.0.0/24        1.1.1.1         imp-null    17                no
ipv4 10.135.0.0/24        1.1.1.1         imp-null    imp-null          no
ipv4 10.200.0.0/24        1.1.1.1         17          imp-null         yes
west-vm#

LDP debugging commands¶

[no] debug mpls ldp KIND¶

Enable or disable debugging messages of a given kind. KIND can be one of:

discovery
errors
event
labels
messages
zebra

LDP Example Configuration¶

Below configuration gives a typical MPLS configuration of a device located in a MPLS backbone. LDP is enabled on two interfaces and will attempt to peer with two neighbors with router-id set to either 1.1.1.1 or 3.3.3.3.

mpls ldp
 router-id 2.2.2.2
 neighbor 1.1.1.1 password test
 neighbor 3.3.3.3 password test
 !
 address-family ipv4
  discovery transport-address 2.2.2.2
  !
  interface eth1
  !
  interface eth3
  !
 exit-address-family
 !

Deploying LDP across a backbone generally is done in a full mesh configuration topology. LDP is typically deployed with an IGP like OSPF, that helps discover the remote IPs. Below example is an OSPF configuration extract that goes with LDP configuration

router ospf
 ospf router-id 2.2.2.2
  network 0.0.0.0/0 area 0
 !

Below output shows the routing entry on the LER side. The OSPF routing entry (10.200.0.0) is associated with Label entry (17), and shows that MPLS push action that traffic to that destination will be applied.

north-vm# show ip route
Codes: K - kernel route, C - connected, S - static, R - RIP,
       O - OSPF, I - IS-IS, B - BGP, E - EIGRP, N - NHRP,
       T - Table, v - VNC, V - VNC-Direct, A - Babel, D - SHARP,
       F - PBR,
       > - selected route, * - FIB route

O>* 1.1.1.1/32 [110/120] via 10.115.0.1, eth2, label 16, 00:00:15
O>* 2.2.2.2/32 [110/20] via 10.115.0.1, eth2, label implicit-null, 00:00:15
O   3.3.3.3/32 [110/10] via 0.0.0.0, loopback1 onlink, 00:01:19
C>* 3.3.3.3/32 is directly connected, loopback1, 00:01:29
O>* 10.0.2.0/24 [110/11] via 10.115.0.1, eth2, label implicit-null, 00:00:15
O   10.100.0.0/24 [110/10] is directly connected, eth1, 00:00:32
C>* 10.100.0.0/24 is directly connected, eth1, 00:00:32
O   10.115.0.0/24 [110/10] is directly connected, eth2, 00:00:25
C>* 10.115.0.0/24 is directly connected, eth2, 00:00:32
O>* 10.135.0.0/24 [110/110] via 10.115.0.1, eth2, label implicit-null, 00:00:15
O>* 10.200.0.0/24 [110/210] via 10.115.0.1, eth2, label 17, 00:00:15
north-vm#

EIGRP¶

DUAL: The Diffusing Update ALgorithm, a Bellman-Ford based routing algorithm used by EIGRP.

EIGRP – Routing Information Protocol is widely deployed interior gateway routing protocol. EIGRP was developed in the 1990’s. EIGRP is a distance-vector protocol and is based on the DUAL algorithms. As a distance-vector protocol, the EIGRP router send updates to its neighbors as networks change, thus allowing the convergence to a known topology.

eigrpd supports EIGRP as described in RFC7868

Starting and Stopping eigrpd¶

The default configuration file name of eigrpd’s is eigrpd.conf. When invocation eigrpd searches directory /etc/frr. If eigrpd.conf is not there next search current directory. If an integrated config is specified configuration is written into frr.conf.

The EIGRP protocol requires interface information maintained by zebra daemon. So running zebra is mandatory to run eigrpd. Thus minimum sequence for running EIGRP is:

# zebra -d
# eigrpd -d

Please note that zebra must be invoked before eigrpd.

To stop eigrpd, please use ::: kill cat /var/run/eigrpd.pid

Certain signals have special meanings to eigrpd.

Signal	Meaning
SIGHUP & SIGUSR1	Rotate the log file
SIGINT & SIGTERM	Sweep all installed EIGRP routes and gracefully terminate

eigrpd invocation options. Common options that can be specified (Common Invocation Options).

EIGRP Configuration¶

router eigrp (1-65535) [vrf NAME]¶: The router eigrp command is necessary to enable EIGRP. To disable EIGRP, use the no router eigrp (1-65535) command. EIGRP must be enabled before carrying out any of the EIGRP commands. Specify vrf NAME if you want eigrp to work within the specified vrf.

no router eigrp (1-65535) [vrf NAME]¶: Disable EIGRP.

network NETWORK¶

no network NETWORK¶

Set the EIGRP enable interface by network. The interfaces which have addresses matching with network are enabled.

This group of commands either enables or disables EIGRP interfaces between certain numbers of a specified network address. For example, if the network for 10.0.0.0/24 is EIGRP enabled, this would result in all the addresses from 10.0.0.0 to 10.0.0.255 being enabled for EIGRP. The no network command will disable EIGRP for the specified network.

Below is very simple EIGRP configuration. Interface eth0 and interface which address match to 10.0.0.0/8 are EIGRP enabled.

!
router eigrp 1
 network 10.0.0.0/8
!

passive-interface (IFNAME|default)¶

no passive-interface IFNAME¶

This command sets the specified interface to passive mode. On passive mode interface, all receiving packets are ignored and eigrpd does not send either multicast or unicast EIGRP packets except to EIGRP neighbors specified with neighbor command. The interface may be specified as default to make eigrpd default to passive on all interfaces.

The default is to be passive on all interfaces.

How to Announce EIGRP route¶

redistribute kernel¶

redistribute kernel metric (1-4294967295) (0-4294967295) (0-255) (1-255) (1-65535)¶

no redistribute kernel¶: redistribute kernel redistributes routing information from kernel route entries into the EIGRP tables. no redistribute kernel disables the routes.

redistribute static¶

redistribute static metric (1-4294967295) (0-4294967295) (0-255) (1-255) (1-65535)¶

no redistribute static¶: redistribute static redistributes routing information from static route entries into the EIGRP tables. no redistribute static disables the routes.

redistribute connected¶

redistribute connected metric (1-4294967295) (0-4294967295) (0-255) (1-255) (1-65535)¶

no redistribute connected¶: Redistribute connected routes into the EIGRP tables. no redistribute connected disables the connected routes in the EIGRP tables. This command redistribute connected of the interface which EIGRP disabled. The connected route on EIGRP enabled interface is announced by default.

redistribute ospf¶

redistribute ospf metric (1-4294967295) (0-4294967295) (0-255) (1-255) (1-65535)¶

no redistribute ospf¶: redistribute ospf redistributes routing information from ospf route entries into the EIGRP tables. no redistribute ospf disables the routes.

redistribute bgp¶

redistribute bgp metric (1-4294967295) (0-4294967295) (0-255) (1-255) (1-65535)¶

no redistribute bgp¶: redistribute bgp redistributes routing information from bgp route entries into the EIGRP tables. no redistribute bgp disables the routes.

Show EIGRP Information¶

show ip eigrp [vrf NAME] topology¶

Display current EIGRP status.

eigrpd> **show ip eigrp topology**
# show ip eigrp topo

EIGRP Topology Table for AS(4)/ID(0.0.0.0)

Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply
       r - reply Status, s - sia Status

P  10.0.2.0/24, 1 successors, FD is 256256, serno: 0
       via Connected, enp0s3

show ip eigrp [vrf NAME] interface¶: Display the list of interfaces associated with a particular eigrp instance.

..index:: show ip eigrp [vrf NAME] neighbor ..clicmd:: show ip eigrp [vrf NAME] neighbor

Display the list of neighbors that have been established within a particular eigrp instance.

EIGRP Debug Commands¶

Debug for EIGRP protocol.

debug eigrp packets¶

Debug eigrp packets

debug eigrp will show EIGRP packets that are sent and received.

debug eigrp transmit¶

Debug eigrp transmit events

debug eigrp transmit will display detailed information about the EIGRP transmit events.

show debugging eigrp¶

Display eigrpd’s debugging option.

show debugging eigrp will show all information currently set for eigrpd debug.

ISIS¶

ISIS is a routing protocol which is described in ISO10589, RFC 1195, RFC 5308. ISIS is an IGP. Compared with RIP, ISIS can provide scalable network support and faster convergence times like OSPF. ISIS is widely used in large networks such as ISP and carrier backbone networks.

Configuring isisd¶

There are no isisd specific options. Common options can be specified (Common Invocation Options) to isisd. isisd needs to acquire interface information from zebra in order to function. Therefore zebra must be running before invoking isisd. Also, if zebra is restarted then isisd must be too.

Like other daemons, isisd configuration is done in ISIS specific configuration file isisd.conf.

ISIS router¶

To start the ISIS process you have to specify the ISIS router. As of this writing, isisd does not support multiple ISIS processes.

[no] router isis WORD¶: Enable or disable the ISIS process by specifying the ISIS domain with ‘WORD’. isisd does not yet support multiple ISIS processes but you must specify the name of ISIS process. The ISIS process name ‘WORD’ is then used for interface (see command ip router isis WORD).

net XX.XXXX. ... .XXX.XX¶

no net XX.XXXX. ... .XXX.XX¶: Set/Unset network entity title (NET) provided in ISO format.

hostname dynamic¶

no hostname dynamic¶: Enable support for dynamic hostname.

area-password [clear | md5] <password>¶

domain-password [clear | md5] <password>¶

no area-password¶

no domain-password¶: Configure the authentication password for an area, respectively a domain, as clear text or md5 one.

log-adjacency-changes¶

no log-adjacency-changes¶: Log changes in adjacency state.

metric-style [narrow | transition | wide]¶

no metric-style¶

Set old-style (ISO 10589) or new-style packet formats:

narrow Use old style of TLVs with narrow metric
transition Send and accept both styles of TLVs during transition
wide Use new style of TLVs to carry wider metric

set-overload-bit¶

no set-overload-bit¶: Set overload bit to avoid any transit traffic.

purge-originator¶

no purge-originator¶: Enable or disable RFC 6232 purge originator identification.

ISIS Timer¶

lsp-gen-interval (1-120)¶

lsp-gen-interval [level-1 | level-2] (1-120)¶

no lsp-gen-interval¶

no lsp-gen-interval [level-1 | level-2]¶: Set minimum interval in seconds between regenerating same LSP, globally, for an area (level-1) or a domain (level-2).

lsp-refresh-interval [level-1 | level-2] (1-65235)¶

no lsp-refresh-interval [level-1 | level-2]¶: Set LSP refresh interval in seconds, globally, for an area (level-1) or a domain (level-2).

max-lsp-lifetime (360-65535)¶

max-lsp-lifetime [level-1 | level-2] (360-65535)¶

no max-lsp-lifetime¶

no max-lsp-lifetime [level-1 | level-2]¶: Set LSP maximum LSP lifetime in seconds, globally, for an area (level-1) or a domain (level-2).

spf-interval (1-120)¶

spf-interval [level-1 | level-2] (1-120)¶

no spf-interval¶

no spf-interval [level-1 | level-2]¶: Set minimum interval between consecutive SPF calculations in seconds.

ISIS region¶

is-type [level-1 | level-1-2 | level-2-only]¶

no is-type¶

Define the ISIS router behavior:

level-1 Act as a station router only
level-1-2 Act as both a station router and an area router
level-2-only Act as an area router only

ISIS interface¶

[no] <ip|ipv6> router isis WORD¶: Activate ISIS adjacency on this interface. Note that the name of ISIS instance must be the same as the one used to configure the ISIS process (see command router isis WORD). To enable IPv4, issue ip router isis WORD; to enable IPv6, issue ipv6 router isis WORD.

isis circuit-type [level-1 | level-1-2 | level-2]¶

no isis circuit-type¶

Configure circuit type for interface:

level-1 Level-1 only adjacencies are formed
level-1-2 Level-1-2 adjacencies are formed
level-2-only Level-2 only adjacencies are formed

isis csnp-interval (1-600)¶

isis csnp-interval (1-600) [level-1 | level-2]¶

no isis csnp-interval¶

no isis csnp-interval [level-1 | level-2]¶: Set CSNP interval in seconds globally, for an area (level-1) or a domain (level-2).

isis hello padding¶: Add padding to IS-IS hello packets.

isis hello-interval (1-600)¶

isis hello-interval (1-600) [level-1 | level-2]¶

no isis hello-interval¶

no isis hello-interval [level-1 | level-2]¶: Set Hello interval in seconds globally, for an area (level-1) or a domain (level-2).

isis hello-multiplier (2-100)¶

isis hello-multiplier (2-100) [level-1 | level-2]¶

no isis hello-multiplier¶

no isis hello-multiplier [level-1 | level-2]¶: Set multiplier for Hello holding time globally, for an area (level-1) or a domain (level-2).

isis metric [(0-255) | (0-16777215)]¶

isis metric [(0-255) | (0-16777215)] [level-1 | level-2]¶

no isis metric¶

no isis metric [level-1 | level-2]¶: Set default metric value globally, for an area (level-1) or a domain (level-2). Max value depend if metric support narrow or wide value (see command metric-style [narrow | transition | wide]).

isis network point-to-point¶

no isis network point-to-point¶: Set network type to ‘Point-to-Point’ (broadcast by default).

isis passive¶

no isis passive¶: Configure the passive mode for this interface.

isis password [clear | md5] <password>¶

no isis password¶: Configure the authentication password (clear or encoded text) for the interface.

isis priority (0-127)¶

isis priority (0-127) [level-1 | level-2]¶

no isis priority¶

no isis priority [level-1 | level-2]¶: Set priority for Designated Router election, globally, for the area (level-1) or the domain (level-2).

isis psnp-interval (1-120)¶

isis psnp-interval (1-120) [level-1 | level-2]¶

no isis psnp-interval¶

no isis psnp-interval [level-1 | level-2]¶: Set PSNP interval in seconds globally, for an area (level-1) or a domain (level-2).

isis three-way-handshake¶

no isis three-way-handshake¶: Enable or disable RFC 5303 Three-Way Handshake for P2P adjacencies. Three-Way Handshake is enabled by default.

Showing ISIS information¶

show isis summary¶: Show summary information about ISIS.

show isis hostname¶: Show information about ISIS node.

show isis interface¶

show isis interface detail¶

show isis interface <interface name>¶: Show state and configuration of ISIS specified interface, or all interfaces if no interface is given with or without details.

show isis neighbor¶

show isis neighbor <System Id>¶

show isis neighbor detail¶: Show state and information of ISIS specified neighbor, or all neighbors if no system id is given with or without details.

show isis database¶

show isis database [detail]¶

show isis database <LSP id> [detail]¶

show isis database detail <LSP id>¶: Show the ISIS database globally, for a specific LSP id without or with details.

show isis topology¶

show isis topology [level-1|level-2]¶: Show topology IS-IS paths to Intermediate Systems, globally, in area (level-1) or domain (level-2).

show ip route isis¶: Show the ISIS routing table, as determined by the most recent SPF calculation.

Traffic Engineering¶

Note

At this time, FRR offers partial support for some of the routing protocol extensions that can be used with MPLS-TE. FRR does not support a complete RSVP-TE solution currently.

mpls-te on¶

no mpls-te¶: Enable Traffic Engineering LSP flooding.

mpls-te router-address <A.B.C.D>¶

no mpls-te router-address¶: Configure stable IP address for MPLS-TE.

show isis mpls-te interface¶

show isis mpls-te interface INTERFACE¶: Show MPLS Traffic Engineering parameters for all or specified interface.

show isis mpls-te router¶: Show Traffic Engineering router parameters.

See also

Traffic Engineering

Debugging ISIS¶

debug isis adj-packets¶

no debug isis adj-packets¶: IS-IS Adjacency related packets.

debug isis checksum-errors¶

no debug isis checksum-errors¶: IS-IS LSP checksum errors.

debug isis events¶

no debug isis events¶: IS-IS Events.

debug isis local-updates¶

no debug isis local-updates¶: IS-IS local update packets.

debug isis packet-dump¶

no debug isis packet-dump¶: IS-IS packet dump.

debug isis protocol-errors¶

no debug isis protocol-errors¶: IS-IS LSP protocol errors.

debug isis route-events¶

no debug isis route-events¶: IS-IS Route related events.

debug isis snp-packets¶

no debug isis snp-packets¶: IS-IS CSNP/PSNP packets.

debug isis spf-events¶

debug isis spf-statistics¶

debug isis spf-triggers¶

no debug isis spf-events¶

no debug isis spf-statistics¶

no debug isis spf-triggers¶: IS-IS Shortest Path First Events, Timing and Statistic Data and triggering events.

debug isis update-packets¶

no debug isis update-packets¶: Update related packets.

show debugging isis¶: Print which ISIS debug level is activate.

ISIS Configuration Examples¶

A simple example, with MD5 authentication enabled:

!
interface eth0
 ip router isis FOO
 isis network point-to-point
 isis circuit-type level-2-only
!
router isis FOO
net 47.0023.0000.0000.0000.0000.0000.0000.1900.0004.00
 metric-style wide
 is-type level-2-only

A Traffic Engineering configuration, with Inter-ASv2 support.

First, the zebra.conf part:

hostname HOSTNAME
password PASSWORD
log file /var/log/zebra.log
!
interface eth0
 ip address 10.2.2.2/24
 link-params
  max-bw 1.25e+07
  max-rsv-bw 1.25e+06
  unrsv-bw 0 1.25e+06
  unrsv-bw 1 1.25e+06
  unrsv-bw 2 1.25e+06
  unrsv-bw 3 1.25e+06
  unrsv-bw 4 1.25e+06
  unrsv-bw 5 1.25e+06
  unrsv-bw 6 1.25e+06
  unrsv-bw 7 1.25e+06
  admin-grp 0xab
!
interface eth1
 ip address 10.1.1.1/24
 link-params
  enable
  metric 100
  max-bw 1.25e+07
  max-rsv-bw 1.25e+06
  unrsv-bw 0 1.25e+06
  unrsv-bw 1 1.25e+06
  unrsv-bw 2 1.25e+06
  unrsv-bw 3 1.25e+06
  unrsv-bw 4 1.25e+06
  unrsv-bw 5 1.25e+06
  unrsv-bw 6 1.25e+06
  unrsv-bw 7 1.25e+06
  neighbor 10.1.1.2 as 65000

Then the isisd.conf itself:

hostname HOSTNAME
password PASSWORD
log file /var/log/isisd.log
!
!
interface eth0
 ip router isis FOO
!
interface eth1
 ip router isis FOO
!
!
router isis FOO
 isis net 47.0023.0000.0000.0000.0000.0000.0000.1900.0004.00
  mpls-te on
  mpls-te router-address 10.1.1.1
!
line vty

NHRP¶

nhrpd is an implementation of the NHRP. NHRP is described in RFC 2332.

NHRP is used to improve the efficiency of routing computer network traffic over NBMA networks. NHRP provides an ARP-like solution that allows a system to dynamically learn the NBMA address of the other systems that are part of that network, allowing these systems to directly communicate without requiring traffic to use an intermediate hop.

NHRP is a client-server protocol. The server side is called the NHS or the hub, while a client is referred to as the NHC or the spoke. When a node is configured as an NHC, it registers its address with the NHS which keeps track of all registered spokes. An NHC client can then query the addresses of other clients from NHS allowing all spokes to communicate directly with each other.

Cisco Dynamic Multipoint VPN (DMVPN) is based on NHRP, and frr nhrpd implements this scenario.

Routing Design¶

nhrpd never handles routing of prefixes itself. You need to run some real routing protocol (e.g. BGP) to advertise routes over the tunnels. What nhrpd does it establishes ‘shortcut routes’ that optimizes the routing protocol to avoid going through extra nodes in NBMA GRE mesh.

nhrpd does route NHRP domain addresses individually using per-host prefixes. This is similar to Cisco FlexVPN; but in contrast to opennhrp which uses a generic subnet route.

To create NBMA GRE tunnel you might use the following (Linux terminal commands):

ip tunnel add gre1 mode gre key 42 ttl 64
ip addr add 10.255.255.2/32 dev gre1
ip link set gre1 up

Note that the IP-address is assigned as host prefix to gre1. nhrpd will automatically create additional host routes pointing to gre1 when a connection with these hosts is established.

The gre1 subnet prefix should be announced by routing protocol from the hub nodes (e.g. BGP ‘network’ announce). This allows the routing protocol to decide which is the closest hub and determine the relay hub on prefix basis when direct tunnel is not established.

nhrpd will redistribute directly connected neighbors to zebra. Within hub nodes, these routes should be internally redistributed using some routing protocol (e.g. iBGP) to allow hubs to be able to relay all traffic.

This can be achieved in hubs with the following bgp configuration (network command defines the GRE subnet):

router bgp 65555
 address-family ipv4 unicast
   network 172.16.0.0/16
   redistribute nhrp
 exit-address-family

Configuring NHRP¶

ip nhrp holdtime (1-65000)¶: Holdtime is the number of seconds that have to pass before stopping to advertise an NHRP NBMA address as valid. It also controls how often NHRP registration requests are sent. By default registrations are sent every one third of the holdtime.

ip nhrp map A.B.C.D|X:X::X:X A.B.C.D|local¶: Map an IP address of a station to the station’s NBMA address.

ip nhrp network-id (1-4294967295)¶: Enable NHRP on this interface and set the interface’s network ID. The network ID is used to allow creating multiple nhrp domains on a router when multiple interfaces are configured on the router. Interfaces configured with the same ID are part of the same logical NBMA network. The ID is a local only parameter and is not sent to other NHRP nodes and so IDs on different nodes do not need to match. When NHRP packets are received on an interface they are assigned to the local NHRP domain for that interface.

ip nhrp nhs A.B.C.D nbma A.B.C.D|FQDN¶: Configure the Next Hop Server address and its NBMA address.

ip nhrp nhs dynamic nbma A.B.C.D¶: Configure the Next Hop Server to have a dynamic address and set its NBMA address.

ip nhrp registration no-unique¶: Allow the client to not set the unique flag in the NHRP packets. This is useful when a station has a dynamic IP address that could change over time.

ip nhrp shortcut¶: Enable shortcut (spoke-to-spoke) tunnels to allow NHC to talk to each others directly after establishing a connection without going through the hub.

ip nhrp mtu¶: Configure NHRP advertised MTU.

Hub Functionality¶

In addition to routing nhrp redistributed host prefixes, the hub nodes are also responsible to send NHRP Traffic Indication messages that trigger creation of the shortcut tunnels.

nhrpd sends Traffic Indication messages based on network traffic captured using NFLOG. Typically you want to send Traffic Indications for network traffic that is routed from gre1 back to gre1 in rate limited manner. This can be achieved with the following iptables rule.

iptables -A FORWARD -i gre1 -o gre1 \\
    -m hashlimit --hashlimit-upto 4/minute --hashlimit-burst 1 \\
    --hashlimit-mode srcip,dstip --hashlimit-srcmask 24 --hashlimit-dstmask 24 \\
    --hashlimit-name loglimit-0 -j NFLOG --nflog-group 1 --nflog-range 128

You can fine tune the src/dstmask according to the prefix lengths you announce internal, add additional IP range matches, or rate limitation if needed. However, the above should be good in most cases.

This kernel NFLOG target’s nflog-group is configured in global nhrp config with:

nhrp nflog-group (1-65535)¶

To start sending these traffic notices out from hubs, use the nhrp per-interface directive:

ip nhrp redirect¶

This enable redirect replies on the NHS similar to ICMP redirects except this is managed by the nhrp protocol. This setting allows spokes to communicate with each others directly.

Integration with IKE¶

nhrpd needs tight integration with IKE daemon for various reasons. Currently only strongSwan is supported as IKE daemon.

nhrpd connects to strongSwan using VICI protocol based on UNIX socket (hardcoded now as /var/run/charon.vici).

strongSwan currently needs few patches applied. Please check out the https://git.alpinelinux.org/user/tteras/strongswan/log/?h=tteras-release and https://git.alpinelinux.org/user/tteras/strongswan/log/?h=tteras git repositories for the patches.

NHRP Events¶

nhrp event socket SOCKET¶: Configure the Unix path for the event socket.

Configuration Example¶

FIXME

OSPFv2¶

OSPF version 2 is a routing protocol which is described in RFC 2328. OSPF is an IGP. Compared with RIP, OSPF can provide scalable network support and faster convergence times. OSPF is widely used in large networks such as ISP backbone and enterprise networks.

OSPF Fundamentals¶

OSPF is, mostly, a link-state routing protocol. In contrast to distance-vector protocols, such as RIP or BGP, where routers describe available paths (i.e. routes) to each other, in link-state protocols routers instead describe the state of their links to their immediate neighbouring routers.

Each router describes their link-state information in a message known as an LSA, which is then propagated through to all other routers in a link-state routing domain, by a process called flooding. Each router thus builds up an LSDB of all the link-state messages. From this collection of LSAs in the LSDB, each router can then calculate the shortest path to any other router, based on some common metric, by using an algorithm such as Edsger Dijkstra’s SPF algorithm.

By describing connectivity of a network in this way, in terms of routers and links rather than in terms of the paths through a network, a link-state protocol can use less bandwidth and converge more quickly than other protocols. A link-state protocol need distribute only one link-state message throughout the link-state domain when a link on any single given router changes state, in order for all routers to reconverge on the best paths through the network. In contrast, distance vector protocols can require a progression of different path update messages from a series of different routers in order to converge.

The disadvantage to a link-state protocol is that the process of computing the best paths can be relatively intensive when compared to distance-vector protocols, in which near to no computation need be done other than (potentially) select between multiple routes. This overhead is mostly negligible for modern embedded CPUs, even for networks with thousands of nodes. The primary scaling overhead lies more in coping with the ever greater frequency of LSA updates as the size of a link-state area increases, in managing the LSDB and required flooding.

This section aims to give a distilled, but accurate, description of the more important workings of OSPF which an administrator may need to know to be able best configure and trouble-shoot OSPF.

OSPF Mechanisms¶

OSPF defines a range of mechanisms, concerned with detecting, describing and propagating state through a network. These mechanisms will nearly all be covered in greater detail further on. They may be broadly classed as:

The Hello Protocol¶

The OSPF Hello protocol allows OSPF to quickly detect changes in two-way reachability between routers on a link. OSPF can additionally avail of other sources of reachability information, such as link-state information provided by hardware, or through dedicated reachability protocols such as BFD.

OSPF also uses the Hello protocol to propagate certain state between routers sharing a link, for example:

Hello protocol configured state, such as the dead-interval.
Router priority, for DR/BDR election.
DR/BDR election results.
Any optional capabilities supported by each router.

The Hello protocol is comparatively trivial and will not be explored in greater detail than here.

LSAs¶

At the heart of OSPF are LSA messages. Despite the name, some LSA s do not, strictly speaking, describe link-state information. Common LSA s describe information such as:

Routers, in terms of their links.
Networks, in terms of attached routers.
Routes, external to a link-state domain:

External Routes

Routes entirely external to OSPF. Routers originating such routes are known as ASBR routers.

Summary Routes

Routes which summarise routing information relating to OSPF areas external to the OSPF link-state area at hand, originated by ABR routers.

LSA Flooding¶

OSPF defines several related mechanisms, used to manage synchronisation of LSDB s between neighbours as neighbours form adjacencies and the propagation, or flooding of new or updated LSA s.

Areas¶

OSPF provides for the protocol to be broken up into multiple smaller and independent link-state areas. Each area must be connected to a common backbone area by an ABR. These ABR routers are responsible for summarising the link-state routing information of an area into Summary LSAs, possibly in a condensed (i.e. aggregated) form, and then originating these summaries into all other areas the ABR is connected to.

Note that only summaries and external routes are passed between areas. As these describe paths, rather than any router link-states, routing between areas hence is by distance-vector, not link-state.

OSPF LSAs¶

The core objects in OSPF are LSA s. Everything else in OSPF revolves around detecting what to describe in LSAs, when to update them, how to flood them throughout a network and how to calculate routes from them.

There are a variety of different LSA s, for purposes such as describing actual link-state information, describing paths (i.e. routes), describing bandwidth usage of links for TE purposes, and even arbitrary data by way of Opaque LSA s.

LSA Header¶

All LSAs share a common header with the following information:

Type

Different types of LSA s describe different things in OSPF. Types include:
- Router LSA
- Network LSA
- Network Summary LSA
- Router Summary LSA
- AS-External LSA
The specifics of the different types of LSA are examined below.
Advertising Router

The Router ID of the router originating the LSA.

See also

ospf router-id A.B.C.D.

LSA ID

The ID of the LSA, which is typically derived in some way from the information the LSA describes, e.g. a Router LSA uses the Router ID as the LSA ID, a Network LSA will have the IP address of the DR as its LSA ID.

The combination of the Type, ID and Advertising Router ID must uniquely identify the LSA. There can however be multiple instances of an LSA with the same Type, LSA ID and Advertising Router ID, see sequence number.
Age

A number to allow stale LSA s to, eventually, be purged by routers from their LSDB s.

The value nominally is one of seconds. An age of 3600, i.e. 1 hour, is called the MaxAge. MaxAge LSAs are ignored in routing calculations. LSAs must be periodically refreshed by their Advertising Router before reaching MaxAge if they are to remain valid.

Routers may deliberately flood LSAs with the age artificially set to 3600 to indicate an LSA is no longer valid. This is called flushing of an LSA.

It is not abnormal to see stale LSAs in the LSDB, this can occur where a router has shutdown without flushing its LSA(s), e.g. where it has become disconnected from the network. Such LSAs do little harm.

Sequence Number

A number used to distinguish newer instances of an LSA from older instances.

Link-State LSAs¶

Of all the various kinds of LSA s, just two types comprise the actual link-state part of OSPF, Router LSA s and Network LSA s. These LSA types are absolutely core to the protocol.

Instances of these LSAs are specific to the link-state area in which they are originated. Routes calculated from these two LSA types are called intra-area routes.

Router LSA

Each OSPF Router must originate a router LSA to describe itself. In it, the router lists each of its OSPF enabled interfaces, for the given link-state area, in terms of:

Cost

The output cost of that interface, scaled inversely to some commonly known reference value, auto-cost reference-bandwidth (1-4294967.

Link Type

Transit Network

A link to a multi-access network, on which the router has at least one Full adjacency with another router.

PtP

A link to a single remote router, with a Full adjacency. No DR is elected on such links; no network LSA is originated for such a link.

Stub: A link with no adjacent neighbours, or a host route.

Link ID and Data

These values depend on the Link Type:

Link Type	Link ID	Link Data
Transit	Link IP address of the DR	Interface IP address
Point-to-Point	Router ID of the remote router	Local interface IP address, or the ifindex for unnumbered links
Stub	IP address	Subnet Mask

Links on a router may be listed multiple times in the Router LSA, e.g. a PtP interface on which OSPF is enabled must always be described by a Stub link in the Router LSA, in addition to being listed as PtP link in the Router LSA if the adjacency with the remote router is Full.

Stub links may also be used as a way to describe links on which OSPF is not spoken, known as passive interfaces, see passive-interface INTERFACE.

Network LSA

On multi-access links (e.g. ethernets, certain kinds of ATM and X.25 configurations), routers elect a DR. The DR is responsible for originating a Network LSA, which helps reduce the information needed to describe multi-access networks with multiple routers attached. The DR also acts as a hub for the flooding of LSA s on that link, thus reducing flooding overheads.

The contents of the Network LSA describes the:
- Subnet Mask
  
  As the LSA ID of a Network LSA must be the IP address of the DR, the Subnet Mask together with the LSA ID gives you the network address.
- Attached Routers
  
  Each router fully-adjacent with the DR is listed in the LSA, by their Router-ID. This allows the corresponding Router LSA s to be easily retrieved from the LSDB.

Summary of Link State LSAs:

LSA Type	LSA ID	LSA Data Describes
Router LSA	Router ID	The OSPF enabled links of the router, within a specific link-state area.
Network LSA	The IP address of the DR for the network	The subnet mask of the network and the Router IDs of all routers on the network

With an LSDB composed of just these two types of LSA, it is possible to construct a directed graph of the connectivity between all routers and networks in a given OSPF link-state area. So, not surprisingly, when OSPF routers build updated routing tables, the first stage of SPF calculation concerns itself only with these two LSA types.

Link-State LSA Examples¶

The example below shows two LSA s, both originated by the same router (Router ID 192.168.0.49) and with the same LSA ID (192.168.0.49), but of different LSA types.

The first LSA being the router LSA describing 192.168.0.49’s links: 2 links to multi-access networks with fully-adjacent neighbours (i.e. Transit links) and 1 being a Stub link (no adjacent neighbours).

The second LSA being a Network LSA, for which 192.168.0.49 is the DR, listing the Router IDs of 4 routers on that network which are fully adjacent with 192.168.0.49.

# show ip ospf database router 192.168.0.49

       OSPF Router with ID (192.168.0.53)

                Router Link States (Area 0.0.0.0)

  LS age: 38
  Options: 0x2  : *|-|-|-|-|-|E|*
  LS Flags: 0x6
  Flags: 0x2 : ASBR
  LS Type: router-LSA
  Link State ID: 192.168.0.49
  Advertising Router: 192.168.0.49
  LS Seq Number: 80000f90
  Checksum: 0x518b
  Length: 60
   Number of Links: 3

    Link connected to: a Transit Network
     (Link ID) Designated Router address: 192.168.1.3
     (Link Data) Router Interface address: 192.168.1.3
      Number of TOS metrics: 0
       TOS 0 Metric: 10

    Link connected to: a Transit Network
     (Link ID) Designated Router address: 192.168.0.49
     (Link Data) Router Interface address: 192.168.0.49
      Number of TOS metrics: 0
       TOS 0 Metric: 10

    Link connected to: Stub Network
     (Link ID) Net: 192.168.3.190
     (Link Data) Network Mask: 255.255.255.255
      Number of TOS metrics: 0
       TOS 0 Metric: 39063
# show ip ospf database network 192.168.0.49

       OSPF Router with ID (192.168.0.53)

                Net Link States (Area 0.0.0.0)

  LS age: 285
  Options: 0x2  : *|-|-|-|-|-|E|*
  LS Flags: 0x6
  LS Type: network-LSA
  Link State ID: 192.168.0.49 (address of Designated Router)
  Advertising Router: 192.168.0.49
  LS Seq Number: 80000074
  Checksum: 0x0103
  Length: 40
  Network Mask: /29
        Attached Router: 192.168.0.49
        Attached Router: 192.168.0.52
        Attached Router: 192.168.0.53
        Attached Router: 192.168.0.54

Note that from one LSA, you can find the other. E.g. Given the Network-LSA you have a list of Router IDs on that network, from which you can then look up, in the local LSDB, the matching Router LSA. From that Router-LSA you may (potentially) find links to other Transit networks and Routers IDs which can be used to lookup the corresponding Router or Network LSA. And in that fashion, one can find all the Routers and Networks reachable from that starting LSA.

Given the Router LSA instead, you have the IP address of the DR of any attached transit links. Network LSAs will have that IP as their LSA ID, so you can then look up that Network LSA and from that find all the attached routers on that link, leading potentially to more links and Network and Router LSAs, etc. etc.

From just the above two LSA s, one can already see the following partial topology:

------------------------ Network: ......
            |            Designated Router IP: 192.168.1.3
            |
      IP: 192.168.1.3
       (transit link)
        (cost: 10)
   Router ID: 192.168.0.49(stub)---------- IP: 192.168.3.190/32
        (cost: 10)        (cost: 39063)
       (transit link)
      IP: 192.168.0.49
            |
            |
------------------------------ Network: 192.168.0.48/29
  |        |           |       Designated Router IP: 192.168.0.49
  |        |           |
  |        |     Router ID: 192.168.0.54
  |        |
  |   Router ID: 192.168.0.53
  |
Router ID: 192.168.0.52

Note the Router IDs, though they look like IP addresses and often are IP addresses, are not strictly speaking IP addresses, nor need they be reachable addresses (though, OSPF will calculate routes to Router IDs).

External LSAs¶

External, or “Type 5”, LSA s describe routing information which is entirely external to OSPF, and is “injected” into OSPF. Such routing information may have come from another routing protocol, such as RIP or BGP, they may represent static routes or they may represent a default route.

An OSPF router which originates External LSA s is known as an ASBR. Unlike the link-state LSA s, and most other LSA s, which are flooded only within the area in which they originate, External LSA s are flooded through-out the OSPF network to all areas capable of carrying External LSA s (Areas).

Routes internal to OSPF (intra-area or inter-area) are always preferred over external routes.

The External LSA describes the following:

IP Network number: The IP Network number of the route is described by the LSA ID field.
IP Network Mask: The body of the External LSA describes the IP Network Mask of the route. This, together with the LSA ID, describes the prefix of the IP route concerned.
Metric: The cost of the External Route. This cost may be an OSPF cost (also known as a “Type 1” metric), i.e. equivalent to the normal OSPF costs, or an externally derived cost (“Type 2” metric) which is not comparable to OSPF costs and always considered larger than any OSPF cost. Where there are both Type 1 and 2 External routes for a route, the Type 1 is always preferred.
Forwarding Address: The address of the router to forward packets to for the route. This may be, and usually is, left as 0 to specify that the ASBR originating the External LSA should be used. There must be an internal OSPF route to the forwarding address, for the forwarding address to be usable.
Tag: An arbitrary 4-bytes of data, not interpreted by OSPF, which may carry whatever information about the route which OSPF speakers desire.

AS External LSA Example¶

To illustrate, below is an example of an External LSA in the LSDB of an OSPF router. It describes a route to the IP prefix of 192.168.165.0/24, originated by the ASBR with Router-ID 192.168.0.49. The metric of 20 is external to OSPF. The forwarding address is 0, so the route should forward to the originating ASBR if selected.

# show ip ospf database external 192.168.165.0
  LS age: 995
  Options: 0x2  : *|-|-|-|-|-|E|*
  LS Flags: 0x9
  LS Type: AS-external-LSA
  Link State ID: 192.168.165.0 (External Network Number)
  Advertising Router: 192.168.0.49
  LS Seq Number: 800001d8
  Checksum: 0xea27
  Length: 36
  Network Mask: /24
        Metric Type: 2 (Larger than any link state path)
        TOS: 0
        Metric: 20
        Forward Address: 0.0.0.0
        External Route Tag: 0

We can add this to our partial topology from above, which now looks like::

--------------------- Network: ......
         |            Designated Router IP: 192.168.1.3
         |
   IP: 192.168.1.3      /---- External route: 192.168.165.0/24
    (transit link)     /                Cost: 20 (External metric)
     (cost: 10)       /
Router ID: 192.168.0.49(stub)---------- IP: 192.168.3.190/32
     (cost: 10)        (cost: 39063)
    (transit link)
   IP: 192.168.0.49
         |
         |
------------------------------ Network: 192.168.0.48/29
  |        |           |       Designated Router IP: 192.168.0.49
  |        |           |
  |        |     Router ID: 192.168.0.54
  |        |
  |   Router ID: 192.168.0.53
  |
Router ID: 192.168.0.52

Summary LSAs¶

Summary LSAs are created by ABR s to summarise the destinations available within one area to other areas. These LSAs may describe IP networks, potentially in aggregated form, or ASBR routers.

Configuring OSPF¶

ospfd accepts all Common Invocation Options.

-n, --instance¶: Specify the instance number for this invocation of ospfd.

-a, --apiserver¶: Enable the OSPF API server. This is required to use ospfclient.

ospfd must acquire interface information from zebra in order to function. Therefore zebra must be running before invoking ospfd. Also, if zebra is restarted then ospfd must be too.

Like other daemons, ospfd configuration is done in OSPF specific configuration file ospfd.conf when the integrated config is not used.

Multi-instance Support¶

OSPF supports multiple instances. Each instance is identified by a positive nonzero integer that must be provided when adding configuration items specific to that instance. Enabling instances is done with /etc/frr/daemons in the following manner:

...
ospfd=yes
ospfd_instances=1,5,6
...

The ospfd_instances variable controls which instances are started and what their IDs are. In this example, after starting FRR you should see the following processes:

# ps -ef | grep "ospfd"
frr      11816     1  0 17:30 ?        00:00:00 /usr/lib/frr/ospfd --daemon -A 127.0.0.1 -n 1
frr      11822     1  0 17:30 ?        00:00:00 /usr/lib/frr/ospfd --daemon -A 127.0.0.1 -n 2
frr      11828     1  0 17:30 ?        00:00:00 /usr/lib/frr/ospfd --daemon -A 127.0.0.1 -n 3

The instance number should be specified in the config when addressing a particular instance:

router ospf 5
   ospf router-id 1.2.3.4
   area 0.0.0.0 authentication message-digest
   ...

Routers¶

To start OSPF process you have to specify the OSPF router.

router ospf [(1-65535)] vrf NAME¶

no router ospf [(1-65535)] vrf NAME¶: Enable or disable the OSPF process.

ospf router-id A.B.C.D¶

no ospf router-id [A.B.C.D]¶: This sets the router-ID of the OSPF process. The router-ID may be an IP address of the router, but need not be - it can be any arbitrary 32bit number. However it MUST be unique within the entire OSPF domain to the OSPF speaker - bad things will happen if multiple OSPF speakers are configured with the same router-ID! If one is not specified then ospfd will obtain a router-ID automatically from zebra.

ospf abr-type TYPE¶

no ospf abr-type TYPE¶

type can be cisco|ibm|shortcut|standard. The “Cisco” and “IBM” types are equivalent.

The OSPF standard for ABR behaviour does not allow an ABR to consider routes through non-backbone areas when its links to the backbone are down, even when there are other ABRs in attached non-backbone areas which still can reach the backbone - this restriction exists primarily to ensure routing-loops are avoided.

With the “Cisco” or “IBM” ABR type, the default in this release of FRR, this restriction is lifted, allowing an ABR to consider summaries learned from other ABRs through non-backbone areas, and hence route via non-backbone areas as a last resort when, and only when, backbone links are down.

Note that areas with fully-adjacent virtual-links are considered to be “transit capable” and can always be used to route backbone traffic, and hence are unaffected by this setting (area A.B.C.D virtual-link A.B.C.D).

More information regarding the behaviour controlled by this command can be found in RFC 3509, and draft-ietf-ospf-shortcut-abr-02.txt.

Quote: “Though the definition of the ABR in the OSPF specification does not require a router with multiple attached areas to have a backbone connection, it is actually necessary to provide successful routing to the inter-area and external destinations. If this requirement is not met, all traffic destined for the areas not connected to such an ABR or out of the OSPF domain, is dropped. This document describes alternative ABR behaviors implemented in Cisco and IBM routers.”

ospf rfc1583compatibility¶

no ospf rfc1583compatibility¶

RFC 2328, the successor to RFC 1583, suggests according to section G.2 (changes) in section 16.4 a change to the path preference algorithm that prevents possible routing loops that were possible in the old version of OSPFv2. More specifically it demands that inter-area paths and intra-area backbone path are now of equal preference but still both preferred to external paths.

This command should NOT be set normally.

log-adjacency-changes [detail]¶

no log-adjacency-changes [detail]¶: Configures ospfd to log changes in adjacency. With the optional detail argument, all changes in adjacency status are shown. Without detail, only changes to full or regressions are shown.

passive-interface INTERFACE¶

no passive-interface INTERFACE¶: Do not speak OSPF interface on the given interface, but do advertise the interface as a stub link in the router-LSA for this router. This allows one to advertise addresses on such connected interfaces without having to originate AS-External/Type-5 LSAs (which have global flooding scope) - as would occur if connected addresses were redistributed into OSPF (Redistribution). This is the only way to advertise non-OSPF links into stub areas.

timers throttle spf DELAY INITIAL-HOLDTIME MAX-HOLDTIME¶

no timers throttle spf¶

This command sets the initial delay, the initial-holdtime and the maximum-holdtime between when SPF is calculated and the event which triggered the calculation. The times are specified in milliseconds and must be in the range of 0 to 600000 milliseconds.

The delay specifies the minimum amount of time to delay SPF calculation (hence it affects how long SPF calculation is delayed after an event which occurs outside of the holdtime of any previous SPF calculation, and also serves as a minimum holdtime).

Consecutive SPF calculations will always be separated by at least ‘hold-time’ milliseconds. The hold-time is adaptive and initially is set to the initial-holdtime configured with the above command. Events which occur within the holdtime of the previous SPF calculation will cause the holdtime to be increased by initial-holdtime, bounded by the maximum-holdtime configured with this command. If the adaptive hold-time elapses without any SPF-triggering event occurring then the current holdtime is reset to the initial-holdtime. The current holdtime can be viewed with show ip ospf, where it is expressed as a multiplier of the initial-holdtime.

router ospf
timers throttle spf 200 400 10000

In this example, the delay is set to 200ms, the initial holdtime is set to 400ms and the maximum holdtime to 10s. Hence there will always be at least 200ms between an event which requires SPF calculation and the actual SPF calculation. Further consecutive SPF calculations will always be separated by between 400ms to 10s, the hold-time increasing by 400ms each time an SPF-triggering event occurs within the hold-time of the previous SPF calculation.

This command supersedes the timers spf command in previous FRR releases.

max-metric router-lsa [on-startup|on-shutdown] (5-86400)¶

max-metric router-lsa administrative¶

no max-metric router-lsa [on-startup|on-shutdown|administrative]¶

This enables RFC 3137 support, where the OSPF process describes its transit links in its router-LSA as having infinite distance so that other routers will avoid calculating transit paths through the router while still being able to reach networks through the router.

This support may be enabled administratively (and indefinitely) or conditionally. Conditional enabling of max-metric router-lsas can be for a period of seconds after startup and/or for a period of seconds prior to shutdown.

Enabling this for a period after startup allows OSPF to converge fully first without affecting any existing routes used by other routers, while still allowing any connected stub links and/or redistributed routes to be reachable. Enabling this for a period of time in advance of shutdown allows the router to gracefully excuse itself from the OSPF domain.

Enabling this feature administratively allows for administrative intervention for whatever reason, for an indefinite period of time. Note that if the configuration is written to file, this administrative form of the stub-router command will also be written to file. If ospfd is restarted later, the command will then take effect until manually deconfigured.

Configured state of this feature as well as current status, such as the number of second remaining till on-startup or on-shutdown ends, can be viewed with the show ip ospf command.

auto-cost reference-bandwidth (1-4294967)¶

no auto-cost reference-bandwidth¶

This sets the reference bandwidth for cost calculations, where this bandwidth is considered equivalent to an OSPF cost of 1, specified in Mbits/s. The default is 100Mbit/s (i.e. a link of bandwidth 100Mbit/s or higher will have a cost of 1. Cost of lower bandwidth links will be scaled with reference to this cost).

This configuration setting MUST be consistent across all routers within the OSPF domain.

network A.B.C.D/M area A.B.C.D¶

network A.B.C.D/M area (0-4294967295)¶

no network A.B.C.D/M area A.B.C.D¶

no network A.B.C.D/M area (0-4294967295)¶

This command specifies the OSPF enabled interface(s). If the interface has an address from range 192.168.1.0/24 then the command below enables ospf on this interface so router can provide network information to the other ospf routers via this interface.

router ospf
network 192.168.1.0/24 area 0.0.0.0

Prefix length in interface must be equal or bigger (i.e. smaller network) than prefix length in network statement. For example statement above doesn’t enable ospf on interface with address 192.168.1.1/23, but it does on interface with address 192.168.1.129/25.

Note that the behavior when there is a peer address defined on an interface changed after release 0.99.7. Currently, if a peer prefix has been configured, then we test whether the prefix in the network command contains the destination prefix. Otherwise, we test whether the network command prefix contains the local address prefix of the interface.

In some cases it may be more convenient to enable OSPF on a per interface/subnet basis (ip ospf area AREA [ADDR]).

Areas¶

area A.B.C.D range A.B.C.D/M¶

area (0-4294967295) range A.B.C.D/M¶

no area A.B.C.D range A.B.C.D/M¶

no area (0-4294967295) range A.B.C.D/M¶

Summarize intra area paths from specified area into one Type-3 summary-LSA announced to other areas. This command can be used only in ABR and ONLY router-LSAs (Type-1) and network-LSAs (Type-2) (i.e. LSAs with scope area) can be summarized. Type-5 AS-external-LSAs can’t be summarized - their scope is AS. Summarizing Type-7 AS-external-LSAs isn’t supported yet by FRR.

router ospf
 network 192.168.1.0/24 area 0.0.0.0
 network 10.0.0.0/8 area 0.0.0.10
 area 0.0.0.10 range 10.0.0.0/8

With configuration above one Type-3 Summary-LSA with routing info 10.0.0.0/8 is announced into backbone area if area 0.0.0.10 contains at least one intra-area network (i.e. described with router or network LSA) from this range.

area A.B.C.D range IPV4_PREFIX not-advertise¶

no area A.B.C.D range IPV4_PREFIX not-advertise¶: Instead of summarizing intra area paths filter them - i.e. intra area paths from this range are not advertised into other areas. This command makes sense in ABR only.

area A.B.C.D range IPV4_PREFIX substitute IPV4_PREFIX¶

no area A.B.C.D range IPV4_PREFIX substitute IPV4_PREFIX¶

Substitute summarized prefix with another prefix.

router ospf
 network 192.168.1.0/24 area 0.0.0.0
 network 10.0.0.0/8 area 0.0.0.10
 area 0.0.0.10 range 10.0.0.0/8 substitute 11.0.0.0/8

One Type-3 summary-LSA with routing info 11.0.0.0/8 is announced into backbone area if area 0.0.0.10 contains at least one intra-area network (i.e. described with router-LSA or network-LSA) from range 10.0.0.0/8. This command makes sense in ABR only.

area A.B.C.D virtual-link A.B.C.D¶

area (0-4294967295) virtual-link A.B.C.D¶

no area A.B.C.D virtual-link A.B.C.D¶

no area (0-4294967295) virtual-link A.B.C.D¶

area A.B.C.D shortcut¶

area (0-4294967295) shortcut¶

no area A.B.C.D shortcut¶

no area (0-4294967295) shortcut¶: Configure the area as Shortcut capable. See RFC 3509. This requires that the ‘abr-type’ be set to ‘shortcut’.

area A.B.C.D stub¶

area (0-4294967295) stub¶

no area A.B.C.D stub¶

no area (0-4294967295) stub¶: Configure the area to be a stub area. That is, an area where no router originates routes external to OSPF and hence an area where all external routes are via the ABR(s). Hence, ABRs for such an area do not need to pass AS-External LSAs (type-5s) or ASBR-Summary LSAs (type-4) into the area. They need only pass Network-Summary (type-3) LSAs into such an area, along with a default-route summary.

area A.B.C.D stub no-summary¶

area (0-4294967295) stub no-summary¶

no area A.B.C.D stub no-summary¶

no area (0-4294967295) stub no-summary¶: Prevents an ospfd ABR from injecting inter-area summaries into the specified stub area.

area A.B.C.D default-cost (0-16777215)¶

no area A.B.C.D default-cost (0-16777215)¶: Set the cost of default-summary LSAs announced to stubby areas.

area A.B.C.D export-list NAME¶

area (0-4294967295) export-list NAME¶

no area A.B.C.D export-list NAME¶

no area (0-4294967295) export-list NAME¶

Filter Type-3 summary-LSAs announced to other areas originated from intra- area paths from specified area.

router ospf
 network 192.168.1.0/24 area 0.0.0.0
 network 10.0.0.0/8 area 0.0.0.10
 area 0.0.0.10 export-list foo
!
access-list foo permit 10.10.0.0/16
access-list foo deny any

With example above any intra-area paths from area 0.0.0.10 and from range 10.10.0.0/16 (for example 10.10.1.0/24 and 10.10.2.128/30) are announced into other areas as Type-3 summary-LSA’s, but any others (for example 10.11.0.0/16 or 10.128.30.16/30) aren’t.

This command is only relevant if the router is an ABR for the specified area.

area A.B.C.D import-list NAME¶

area (0-4294967295) import-list NAME¶

no area A.B.C.D import-list NAME¶

no area (0-4294967295) import-list NAME¶: Same as export-list, but it applies to paths announced into specified area as Type-3 summary-LSAs.

area A.B.C.D filter-list prefix NAME in¶

area A.B.C.D filter-list prefix NAME out¶

area (0-4294967295) filter-list prefix NAME in¶

area (0-4294967295) filter-list prefix NAME out¶

no area A.B.C.D filter-list prefix NAME in¶

no area A.B.C.D filter-list prefix NAME out¶

no area (0-4294967295) filter-list prefix NAME in¶

no area (0-4294967295) filter-list prefix NAME out¶: Filtering Type-3 summary-LSAs to/from area using prefix lists. This command makes sense in ABR only.

area A.B.C.D authentication¶

area (0-4294967295) authentication¶

no area A.B.C.D authentication¶

no area (0-4294967295) authentication¶: Specify that simple password authentication should be used for the given area.

area A.B.C.D authentication message-digest¶

area (0-4294967295) authentication message-digest¶

Specify that OSPF packets must be authenticated with MD5 HMACs within the given area. Keying material must also be configured on a per-interface basis (ip ospf message-digest-key).

MD5 authentication may also be configured on a per-interface basis (ip ospf authentication message-digest). Such per-interface settings will override any per-area authentication setting.

Interfaces¶

ip ospf area AREA [ADDR]¶

no ip ospf area [ADDR]¶

Enable OSPF on the interface, optionally restricted to just the IP address given by ADDR, putting it in the AREA area. Per interface area settings take precedence to network commands (network A.B.C.D/M area A.B.C.D).

If you have a lot of interfaces, and/or a lot of subnets, then enabling OSPF via this command may result in a slight performance improvement.

ip ospf authentication-key AUTH_KEY¶

no ip ospf authentication-key¶

Set OSPF authentication key to a simple password. After setting AUTH_KEY, all OSPF packets are authenticated. AUTH_KEY has length up to 8 chars.

Simple text password authentication is insecure and deprecated in favour of MD5 HMAC authentication.

ip ospf authentication message-digest¶

Specify that MD5 HMAC authentication must be used on this interface. MD5 keying material must also be configured. Overrides any authentication enabled on a per-area basis (area A.B.C.D authentication message-digest)

Note that OSPF MD5 authentication requires that time never go backwards (correct time is NOT important, only that it never goes backwards), even across resets, if ospfd is to be able to promptly reestablish adjacencies with its neighbours after restarts/reboots. The host should have system time be set at boot from an external or non-volatile source (e.g. battery backed clock, NTP, etc.) or else the system clock should be periodically saved to non-volatile storage and restored at boot if MD5 authentication is to be expected to work reliably.

ip ospf message-digest-key KEYID md5 KEY¶

no ip ospf message-digest-key¶

Set OSPF authentication key to a cryptographic password. The cryptographic algorithm is MD5.

KEYID identifies secret key used to create the message digest. This ID is part of the protocol and must be consistent across routers on a link.

KEY is the actual message digest key, of up to 16 chars (larger strings will be truncated), and is associated with the given KEYID.

ip ospf cost (1-65535)¶

no ip ospf cost¶: Set link cost for the specified interface. The cost value is set to router-LSA’s metric field and used for SPF calculation.

ip ospf dead-interval (1-65535)¶

ip ospf dead-interval minimal hello-multiplier (2-20)¶

no ip ospf dead-interval¶

Set number of seconds for RouterDeadInterval timer value used for Wait Timer and Inactivity Timer. This value must be the same for all routers attached to a common network. The default value is 40 seconds.

If ‘minimal’ is specified instead, then the dead-interval is set to 1 second and one must specify a hello-multiplier. The hello-multiplier specifies how many Hellos to send per second, from 2 (every 500ms) to 20 (every 50ms). Thus one can have 1s convergence time for OSPF. If this form is specified, then the hello-interval advertised in Hello packets is set to 0 and the hello-interval on received Hello packets is not checked, thus the hello-multiplier need NOT be the same across multiple routers on a common link.

ip ospf hello-interval (1-65535)¶

no ip ospf hello-interval¶

Set number of seconds for HelloInterval timer value. Setting this value, Hello packet will be sent every timer value seconds on the specified interface. This value must be the same for all routers attached to a common network. The default value is 10 seconds.

This command has no effect if ip ospf dead-interval minimal hello-multiplier (2-20) is also specified for the interface.

ip ospf network (broadcast|non-broadcast|point-to-multipoint|point-to-point)¶: When configuring a point-to-point network on an interface and the interface has a /32 address associated with then OSPF will treat the interface as being unnumbered. If you are doing this you must set the net.ipv4.conf.<interface name>.rp_filter value to 0. In order for the ospf multicast packets to be delivered by the kernel.

no ip ospf network¶: Set explicitly network type for specified interface.

ip ospf priority (0-255)¶

no ip ospf priority¶: Set RouterPriority integer value. The router with the highest priority will be more eligible to become Designated Router. Setting the value to 0, makes the router ineligible to become Designated Router. The default value is 1.

ip ospf retransmit-interval (1-65535)¶

no ip ospf retransmit interval¶: Set number of seconds for RxmtInterval timer value. This value is used when retransmitting Database Description and Link State Request packets. The default value is 5 seconds.

ip ospf transmit-delay¶

no ip ospf transmit-delay¶: Set number of seconds for InfTransDelay value. LSAs’ age should be incremented by this value when transmitting. The default value is 1 second.

ip ospf area (A.B.C.D|(0-4294967295))¶

no ip ospf area¶: Enable ospf on an interface and set associated area.

Redistribution¶

redistribute (kernel|connected|static|rip|bgp)¶

redistribute (kernel|connected|static|rip|bgp) ROUTE-MAP¶

redistribute (kernel|connected|static|rip|bgp) metric-type (1|2)¶

redistribute (kernel|connected|static|rip|bgp) metric-type (1|2) route-map WORD¶

redistribute (kernel|connected|static|rip|bgp) metric (0-16777214)¶

redistribute (kernel|connected|static|rip|bgp) metric (0-16777214) route-map WORD¶

redistribute (kernel|connected|static|rip|bgp) metric-type (1|2) metric (0-16777214)¶

redistribute (kernel|connected|static|rip|bgp) metric-type (1|2) metric (0-16777214) route-map WORD¶

no redistribute (kernel|connected|static|rip|bgp)¶

Redistribute routes of the specified protocol or kind into OSPF, with the metric type and metric set if specified, filtering the routes using the given route-map if specified. Redistributed routes may also be filtered with distribute-lists, see ospf distribute-list configuration.

Redistributed routes are distributed as into OSPF as Type-5 External LSAs into links to areas that accept external routes, Type-7 External LSAs for NSSA areas and are not redistributed at all into Stub areas, where external routes are not permitted.

Note that for connected routes, one may instead use the passive-interface configuration.

See also

clicmd:passive-interface INTERFACE.

default-information originate¶

default-information originate metric (0-16777214)¶

default-information originate metric (0-16777214) metric-type (1|2)¶

default-information originate metric (0-16777214) metric-type (1|2) route-map WORD¶

default-information originate always¶

default-information originate always metric (0-16777214)¶

default-information originate always metric (0-16777214) metric-type (1|2)¶

default-information originate always metric (0-16777214) metric-type (1|2) route-map WORD¶

no default-information originate¶: Originate an AS-External (type-5) LSA describing a default route into all external-routing capable areas, of the specified metric and metric type. If the ‘always’ keyword is given then the default is always advertised, even when there is no default present in the routing table.

distribute-list NAME out (kernel|connected|static|rip|ospf¶

no distribute-list NAME out (kernel|connected|static|rip|ospf¶

Apply the access-list filter, NAME, to redistributed routes of the given type before allowing the routes to redistributed into OSPF (ospf redistribution).

default-metric (0-16777214)¶

no default-metric¶

distance (1-255)¶

no distance (1-255)¶

distance ospf (intra-area|inter-area|external) (1-255)¶

no distance ospf¶

router zebra¶

no router zebra¶

Showing Information¶

show ip ospf¶: Show information on a variety of general OSPF and area state and configuration information.

show ip ospf interface [INTERFACE]¶: Show state and configuration of OSPF the specified interface, or all interfaces if no interface is given.

show ip ospf neighbor¶

show ip ospf neighbor INTERFACE¶

show ip ospf neighbor detail¶

show ip ospf neighbor INTERFACE detail¶

show ip ospf database¶

show ip ospf database (asbr-summary|external|network|router|summary)¶

show ip ospf database (asbr-summary|external|network|router|summary) LINK-STATE-ID¶

show ip ospf database (asbr-summary|external|network|router|summary) LINK-STATE-ID adv-router ADV-ROUTER¶

show ip ospf database (asbr-summary|external|network|router|summary) adv-router ADV-ROUTER¶

show ip ospf database (asbr-summary|external|network|router|summary) LINK-STATE-ID self-originate¶

show ip ospf database (asbr-summary|external|network|router|summary) self-originate¶

show ip ospf database max-age¶

show ip ospf database self-originate¶

show ip ospf route¶: Show the OSPF routing table, as determined by the most recent SPF calculation.

Opaque LSA¶

ospf opaque-lsa¶

capability opaque¶

no ospf opaque-lsa¶

no capability opaque¶: ospfd supports Opaque LSA (RFC 2370) as partial support for MPLS Traffic Engineering LSAs. The opaque-lsa capability must be enabled in the configuration. An alternate command could be “mpls-te on” (Traffic Engineering). Note that FRR offers only partial support for some of the routing protocol extensions that are used with MPLS-TE; it does not support a complete RSVP-TE solution.

show ip ospf database (opaque-link|opaque-area|opaque-external)¶

show ip ospf database (opaque-link|opaque-area|opaque-external) LINK-STATE-ID¶

show ip ospf database (opaque-link|opaque-area|opaque-external) LINK-STATE-ID adv-router ADV-ROUTER¶

show ip ospf database (opaque-link|opaque-area|opaque-external) adv-router ADV-ROUTER¶

show ip ospf database (opaque-link|opaque-area|opaque-external) LINK-STATE-ID self-originate¶

show ip ospf database (opaque-link|opaque-area|opaque-external) self-originate¶: Show Opaque LSA from the database.

Traffic Engineering¶

Note

At this time, FRR offers partial support for some of the routing protocol extensions that can be used with MPLS-TE. FRR does not support a complete RSVP-TE solution currently.

mpls-te on¶

no mpls-te¶: Enable Traffic Engineering LSA flooding.

mpls-te router-address <A.B.C.D>¶: Configure stable IP address for MPLS-TE. This IP address is then advertise in Opaque LSA Type-10 TLV=1 (TE) option 1 (Router-Address).

mpls-te inter-as area <area-id>|as¶

no mpls-te inter-as¶: Enable RFC 5392 support - Inter-AS TE v2 - to flood Traffic Engineering parameters of Inter-AS link. 2 modes are supported: AREA and AS; LSA are flood in AREA <area-id> with Opaque Type-10, respectively in AS with Opaque Type-11. In all case, Opaque-LSA TLV=6.

show ip ospf mpls-te interface¶

show ip ospf mpls-te interface INTERFACE¶: Show MPLS Traffic Engineering parameters for all or specified interface.

show ip ospf mpls-te router¶: Show Traffic Engineering router parameters.

Router Information¶

router-info [as | area]¶

no router-info¶: Enable Router Information (RFC 4970) LSA advertisement with AS scope (default) or Area scope flooding when area is specified. Old syntax router-info area <A.B.C.D> is always supported but mark as deprecated as the area ID is no more necessary. Indeed, router information support multi-area and detect automatically the areas.

pce address <A.B.C.D>¶

no pce address¶

pce domain as (0-65535)¶

no pce domain as (0-65535)¶

pce neighbor as (0-65535)¶

no pce neighbor as (0-65535)¶

pce flag BITPATTERN¶

no pce flag¶

pce scope BITPATTERN¶

no pce scope¶: The commands are conform to RFC 5088 and allow OSPF router announce Path Computation Element (PCE) capabilities through the Router Information (RI) LSA. Router Information must be enable prior to this. The command set/unset respectively the PCE IP address, Autonomous System (AS) numbers of controlled domains, neighbor ASs, flag and scope. For flag and scope, please refer to :rfc`5088` for the BITPATTERN recognition. Multiple ‘pce neighbor’ command could be specified in order to specify all PCE neighbours.

show ip ospf router-info¶: Show Router Capabilities flag.

show ip ospf router-info pce¶: Show Router Capabilities PCE parameters.

Segment Routing¶

This is an EXPERIMENTAL support of Segment Routing as per draft draft-ietf-ospf-segment-routing-extensions-24.txt for MPLS dataplane.

[no] segment-routing on¶: Enable Segment Routing. Even if this also activate routing information support, it is preferable to also activate routing information, and set accordingly the Area or AS flooding.

[no] segment-routing global-block (0-1048575) (0-1048575)¶: Fix the Segment Routing Global Block i.e. the label range used by MPLS to store label in the MPLS FIB.

[no] segment-routing node-msd (1-16)¶: Fix the Maximum Stack Depth supported by the router. The value depend of the MPLS dataplane. E.g. for Linux kernel, since version 4.13 it is 32.

[no] segment-routing prefix A.B.C.D/M index (0-65535) [no-php-flag]¶: Set the Segment Routing index for the specified prefix. Note that, only prefix with /32 corresponding to a loopback interface are currently supported. The ‘no-php-flag’ means NO Penultimate Hop Popping that allows SR node to request to its neighbor to not pop the label.

show ip ospf database segment-routing <adv-router ADVROUTER|self-originate> [json]¶: Show Segment Routing Data Base, all SR nodes, specific advertised router or self router. Optional JSON output can be obtained by appending ‘json’ to the end of the command.

Debugging OSPF¶

debug ospf packet (hello|dd|ls-request|ls-update|ls-ack|all) (send|recv) [detail]¶

no debug ospf packet (hello|dd|ls-request|ls-update|ls-ack|all) (send|recv) [detail]¶: Dump Packet for debugging

debug ospf ism¶

debug ospf ism (status|events|timers)¶

no debug ospf ism¶

no debug ospf ism (status|events|timers)¶: Show debug information of Interface State Machine

debug ospf nsm¶

debug ospf nsm (status|events|timers)¶

no debug ospf nsm¶

no debug ospf nsm (status|events|timers)¶: Show debug information of Network State Machine

debug ospf event¶

no debug ospf event¶: Show debug information of OSPF event

debug ospf nssa¶

no debug ospf nssa¶: Show debug information about Not So Stub Area

debug ospf lsa¶

debug ospf lsa (generate|flooding|refresh)¶

no debug ospf lsa¶

no debug ospf lsa (generate|flooding|refresh)¶: Show debug detail of Link State messages

debug ospf te¶

no debug ospf te¶: Show debug information about Traffic Engineering LSA

debug ospf zebra¶

debug ospf zebra (interface|redistribute)¶

no debug ospf zebra¶

no debug ospf zebra (interface|redistribute)¶: Show debug information of ZEBRA API

show debugging ospf¶

OSPF Configuration Examples¶

A simple example, with MD5 authentication enabled:

!
interface bge0
 ip ospf authentication message-digest
 ip ospf message-digest-key 1 md5 ABCDEFGHIJK
!
router ospf
 network 192.168.0.0/16 area 0.0.0.1
 area 0.0.0.1 authentication message-digest

An ABR router, with MD5 authentication and performing summarisation of networks between the areas:

!
password ABCDEF
log file /var/log/frr/ospfd.log
service advanced-vty
!
interface eth0
 ip ospf authentication message-digest
 ip ospf message-digest-key 1 md5 ABCDEFGHIJK
!
interface ppp0
!
interface br0
 ip ospf authentication message-digest
 ip ospf message-digest-key 2 md5 XYZ12345
!
router ospf
 ospf router-id 192.168.0.1
 redistribute connected
 passive interface ppp0
 network 192.168.0.0/24 area 0.0.0.0
 network 10.0.0.0/16 area 0.0.0.0
 network 192.168.1.0/24 area 0.0.0.1
 area 0.0.0.0 authentication message-digest
 area 0.0.0.0 range 10.0.0.0/16
 area 0.0.0.0 range 192.168.0.0/24
 area 0.0.0.1 authentication message-digest
 area 0.0.0.1 range 10.2.0.0/16
!

A Traffic Engineering configuration, with Inter-ASv2 support.

First, the zebra.conf part:

interface eth0
 ip address 198.168.1.1/24
 link-params
  enable
  admin-grp 0xa1
  metric 100
  max-bw 1.25e+07
  max-rsv-bw 1.25e+06
  unrsv-bw 0 1.25e+06
  unrsv-bw 1 1.25e+06
  unrsv-bw 2 1.25e+06
  unrsv-bw 3 1.25e+06
  unrsv-bw 4 1.25e+06
  unrsv-bw 5 1.25e+06
  unrsv-bw 6 1.25e+06
  unrsv-bw 7 1.25e+06
!
interface eth1
 ip address 192.168.2.1/24
 link-params
  enable
  metric 10
  max-bw 1.25e+07
  max-rsv-bw 1.25e+06
  unrsv-bw 0 1.25e+06
  unrsv-bw 1 1.25e+06
  unrsv-bw 2 1.25e+06
  unrsv-bw 3 1.25e+06
  unrsv-bw 4 1.25e+06
  unrsv-bw 5 1.25e+06
  unrsv-bw 6 1.25e+06
  unrsv-bw 7 1.25e+06
  neighbor 192.168.2.2 as 65000
   hostname HOSTNAME
   password PASSWORD
   log file /var/log/zebra.log
   !
   interface eth0
    ip address 198.168.1.1/24
    link-params
     enable
     admin-grp 0xa1
     metric 100
     max-bw 1.25e+07
     max-rsv-bw 1.25e+06
     unrsv-bw 0 1.25e+06
     unrsv-bw 1 1.25e+06
     unrsv-bw 2 1.25e+06
     unrsv-bw 3 1.25e+06
     unrsv-bw 4 1.25e+06
     unrsv-bw 5 1.25e+06
     unrsv-bw 6 1.25e+06
     unrsv-bw 7 1.25e+06
   !
   interface eth1
    ip address 192.168.2.1/24
    link-params
     enable
     metric 10
     max-bw 1.25e+07
     max-rsv-bw 1.25e+06
     unrsv-bw 0 1.25e+06
     unrsv-bw 1 1.25e+06
     unrsv-bw 2 1.25e+06
     unrsv-bw 3 1.25e+06
     unrsv-bw 4 1.25e+06
     unrsv-bw 5 1.25e+06
     unrsv-bw 6 1.25e+06
     unrsv-bw 7 1.25e+06
     neighbor 192.168.2.2 as 65000

Then the ospfd.conf itself:

hostname HOSTNAME
password PASSWORD
log file /var/log/ospfd.log
!
!
interface eth0
 ip ospf hello-interval 60
 ip ospf dead-interval 240
!
interface eth1
 ip ospf hello-interval 60
 ip ospf dead-interval 240
!
!
router ospf
 ospf router-id 192.168.1.1
 network 192.168.0.0/16 area 1
 ospf opaque-lsa
 mpls-te
 mpls-te router-address 192.168.1.1
 mpls-te inter-as area 1
!
line vty

A router information example with PCE advertisement:

!
router ospf
 ospf router-id 192.168.1.1
 network 192.168.0.0/16 area 1
 capability opaque
 mpls-te
 mpls-te router-address 192.168.1.1
 router-info area 0.0.0.1
 pce address 192.168.1.1
 pce flag 0x80
 pce domain as 65400
 pce neighbor as 65500
 pce neighbor as 65200
 pce scope 0x80
!

OSPFv3¶

ospf6d is a daemon support OSPF version 3 for IPv6 network. OSPF for IPv6 is described in RFC 2740.

OSPF6 router¶

router ospf6¶

ospf6 router-id A.B.C.D¶: Set router’s Router-ID.

interface IFNAME area AREA¶: Bind interface to specified area, and start sending OSPF packets. area can be specified as 0.

timers throttle spf DELAY INITIAL-HOLDTIME MAX-HOLDTIME¶

no timers throttle spf¶

This command sets the initial delay, the initial-holdtime and the maximum-holdtime between when SPF is calculated and the event which triggered the calculation. The times are specified in milliseconds and must be in the range of 0 to 600000 milliseconds.

The delay specifies the minimum amount of time to delay SPF calculation (hence it affects how long SPF calculation is delayed after an event which occurs outside of the holdtime of any previous SPF calculation, and also serves as a minimum holdtime).

Consecutive SPF calculations will always be separated by at least ‘hold-time’ milliseconds. The hold-time is adaptive and initially is set to the initial-holdtime configured with the above command. Events which occur within the holdtime of the previous SPF calculation will cause the holdtime to be increased by initial-holdtime, bounded by the maximum-holdtime configured with this command. If the adaptive hold-time elapses without any SPF-triggering event occurring then the current holdtime is reset to the initial-holdtime.

router ospf6
 timers throttle spf 200 400 10000

In this example, the delay is set to 200ms, the initial holdtime is set to 400ms and the maximum holdtime to 10s. Hence there will always be at least 200ms between an event which requires SPF calculation and the actual SPF calculation. Further consecutive SPF calculations will always be separated by between 400ms to 10s, the hold-time increasing by 400ms each time an SPF-triggering event occurs within the hold-time of the previous SPF calculation.

auto-cost reference-bandwidth COST¶

no auto-cost reference-bandwidth¶

This sets the reference bandwidth for cost calculations, where this bandwidth is considered equivalent to an OSPF cost of 1, specified in Mbits/s. The default is 100Mbit/s (i.e. a link of bandwidth 100Mbit/s or higher will have a cost of 1. Cost of lower bandwidth links will be scaled with reference to this cost).

This configuration setting MUST be consistent across all routers within the OSPF domain.

OSPF6 area¶

Area support for OSPFv3 is not yet implemented.

OSPF6 interface¶

ipv6 ospf6 cost COST¶: Sets interface’s output cost. Default value depends on the interface bandwidth and on the auto-cost reference bandwidth.

ipv6 ospf6 hello-interval HELLOINTERVAL¶: Sets interface’s Hello Interval. Default 10

ipv6 ospf6 dead-interval DEADINTERVAL¶: Sets interface’s Router Dead Interval. Default value is 40.

ipv6 ospf6 retransmit-interval RETRANSMITINTERVAL¶: Sets interface’s Rxmt Interval. Default value is 5.

ipv6 ospf6 priority PRIORITY¶: Sets interface’s Router Priority. Default value is 1.

ipv6 ospf6 transmit-delay TRANSMITDELAY¶: Sets interface’s Inf-Trans-Delay. Default value is 1.

ipv6 ospf6 network (broadcast|point-to-point)¶: Set explicitly network type for specified interface.

Redistribute routes to OSPF6¶

redistribute static¶

redistribute connected¶

redistribute ripng¶

Showing OSPF6 information¶

show ipv6 ospf6 [INSTANCE_ID]¶: INSTANCE_ID is an optional OSPF instance ID. To see router ID and OSPF instance ID, simply type “show ipv6 ospf6 <cr>”.

show ipv6 ospf6 database¶: This command shows LSA database summary. You can specify the type of LSA.

show ipv6 ospf6 interface¶: To see OSPF interface configuration like costs.

show ipv6 ospf6 neighbor¶: Shows state and chosen (Backup) DR of neighbor.

show ipv6 ospf6 request-list A.B.C.D¶: Shows requestlist of neighbor.

show ipv6 route ospf6¶: This command shows internal routing table.

show ipv6 ospf6 zebra¶: Shows state about what is being redistributed between zebra and OSPF6

OSPF6 Configuration Examples¶

Example of ospf6d configured on one interface and area:

interface eth0
 ipv6 ospf6 instance-id 0
!
router ospf6
 ospf6 router-id 212.17.55.53
 area 0.0.0.0 range 2001:770:105:2::/64
 interface eth0 area 0.0.0.0
!

PIM¶

PIM – Protocol Independent Multicast

pimd supports pim-sm as well as igmp v2 and v3. pim is vrf aware and can work within the context of vrf’s in order to do S,G mrouting. Additionally PIM can be used in the EVPN underlay network for optimizing forwarding of overlay BUM traffic.

Note

On Linux for PIM-SM operation you must have kernel version 4.18 or greater. To use PIM for EVPN BUM forwarding, kernels 5.0 or greater are required. OpenBSD has no multicast support and FreeBSD, NetBSD and Solaris only have support for SSM.

Starting and Stopping pimd¶

The default configuration file name of pimd’s is pimd.conf. When invoked pimd searches directory /etc/frr. If pimd.conf is not there then next search current directory.

pimd requires zebra for proper operation. Additionally pimd depends on routing properly setup and working in the network that it is working on.

# zebra -d
# pimd -d

Please note that zebra must be invoked before pimd.

To stop pimd please use:

kill `cat /var/run/pimd.pid`

Certain signals have special meanings to pimd.

Signal	Meaning
SIGUSR1	Rotate the pimd logfile
SIGINT SIGTERM	pimd sweeps all installed PIM mroutes then terminates gracefully.

pimd invocation options. Common options that can be specified (Common Invocation Options).

ip pim rp A.B.C.D A.B.C.D/M¶: In order to use pim, it is necessary to configure a RP for join messages to be sent to. Currently the only methodology to do this is via static rp commands. All routers in the pim network must agree on these values. The first ip address is the RP’s address and the second value is the matching prefix of group ranges covered. This command is vrf aware, to configure for a vrf, enter the vrf submode.

ip pim spt-switchover infinity-and-beyond¶: On the last hop router if it is desired to not switch over to the SPT tree. Configure this command. This command is vrf aware, to configure for a vrf, enter the vrf submode.

ip pim ecmp¶: If pim has the a choice of ECMP nexthops for a particular RPF, pim will cause S,G flows to be spread out amongst the nexthops. If this command is not specified then the first nexthop found will be used. This command is vrf aware, to configure for a vrf, enter the vrf submode.

ip pim ecmp rebalance¶: If pim is using ECMP and an interface goes down, cause pim to rebalance all S,G flows across the remaining nexthops. If this command is not configured pim only modifies those S,G flows that were using the interface that went down. This command is vrf aware, to configure for a vrf, enter the vrf submode.

ip pim join-prune-interval (60-600)¶: Modify the join/prune interval that pim uses to the new value. Time is specified in seconds. This command is vrf aware, to configure for a vrf, enter the vrf submode.

ip pim keep-alive-timer (31-60000)¶: Modify the time out value for a S,G flow from 31-60000 seconds. 31 seconds is chosen for a lower bound because some hardware platforms cannot see data flowing in better than 30 second chunks. This command is vrf aware, to configure for a vrf, enter the vrf submode.

ip pim packets (1-100)¶: When processing packets from a neighbor process the number of packets incoming at one time before moving on to the next task. The default value is 3 packets. This command is only useful at scale when you can possibly have a large number of pim control packets flowing. This command is vrf aware, to configure for a vrf, enter the vrf submode.

ip pim register-suppress-time (5-60000)¶: Modify the time that pim will register suppress a FHR will send register notifications to the kernel. This command is vrf aware, to configure for a vrf, enter the vrf submode.

ip pim send-v6-secondary¶: When sending pim hello packets tell pim to send any v6 secondary addresses on the interface. This information is used to allow pim to use v6 nexthops in it’s decision for RPF lookup. This command is vrf aware, to configure for a vrf, enter the vrf submode.

ip pim ssm prefix-list WORD¶: Specify a range of group addresses via a prefix-list that forces pim to never do SM over. This command is vrf aware, to configure for a vrf, enter the vrf submode.

ip multicast rpf-lookup-mode WORD¶

Modify how PIM does RPF lookups in the zebra routing table. You can use these choices:

longer-prefix: Lookup the RPF in both tables using the longer prefix as a match
lower-distance: Lookup the RPF in both tables using the lower distance as a match
mrib-only: Lookup in the Multicast RIB only
mrib-then-urib: Lookup in the Multicast RIB then the Unicast Rib, returning first found. This is the default value for lookup if this command is not entered
urib-only: Lookup in the Unicast Rib only.

ip igmp generate-query-once [version (2-3)]¶: Generate IGMP query (v2/v3) on user requirement. This will not depend on the existing IGMP general query timer.If no version is provided in the cli, it will be considered as default v2 query.This is a hidden command.

PIM Interface Configuration¶

PIM interface commands allow you to configure an interface as either a Receiver or a interface that you would like to form pim neighbors on. If the interface is in a vrf, enter the interface command with the vrf keyword at the end.

ip pim bfd¶: Turns on BFD support for PIM for this interface.

ip pim bsm¶: Tell pim that we would like to use this interface to process bootstrap messages. This is enabled by default. ‘no’ form of this command is used to restrict bsm messages on this interface.

ip pim unicast-bsm¶: Tell pim that we would like to allow interface to process unicast bootstrap messages. This is enabled by default. ‘no’ form of this command is used to restrict processing of unicast bsm messages on this interface.

ip pim drpriority (1-4294967295)¶: Set the DR Priority for the interface. This command is useful to allow the user to influence what node becomes the DR for a lan segment.

ip pim hello (1-180) (1-180)¶: Set the pim hello and hold interval for a interface.

ip pim¶: Tell pim that we would like to use this interface to form pim neighbors over. Please note that this command does not enable the reception of IGMP reports on the interface. Refer to the next ip igmp command for IGMP management.

ip igmp¶: Tell pim to receive IGMP reports and Query on this interface. The default version is v3. This command is useful on a LHR.

ip igmp join A.B.C.D [A.B.C.D]¶: Join multicast group or source-group on an interface.

ip igmp query-interval (1-1800)¶: Set the IGMP query interval that PIM will use.

ip igmp query-max-response-time (10-250)¶: Set the IGMP query response timeout value. If an report is not returned in the specified time we will assume the S,G or *,G has timed out.

ip igmp version (2-3)¶: Set the IGMP version used on this interface. The default value is 3.

ip multicast boundary oil WORD¶: Set a pim multicast boundary, based upon the WORD prefix-list. If a pim join or IGMP report is received on this interface and the Group is denied by the prefix-list, PIM will ignore the join or report.

ip igmp last-member-query-count (1-7)¶: Set the IGMP last member query count. The default value is 2. ‘no’ form of this command is used to to configure back to the default value.

ip igmp last-member-query-interval (1-255)¶: Set the IGMP last member query interval in deciseconds. The default value is 10 deciseconds. ‘no’ form of this command is used to to configure back to the default value.

ip mroute INTERFACE A.B.C.D [A.B.C.D]¶: Set a static multicast route for a traffic coming on the current interface to be forwarded on the given interface if the traffic matches the group address and optionally the source address.

PIM Multicast RIB insertion:¶

In order to influence Multicast RPF lookup, it is possible to insert into zebra routes for the Multicast RIB. These routes are only used for RPF lookup and will not be used by zebra for insertion into the kernel or for normal rib processing. As such it is possible to create weird states with these commands. Use with caution. Most of the time this will not be necessary.

ip mroute A.B.C.D/M A.B.C.D (1-255)¶: Insert into the Multicast Rib Route A.B.C.D/M with specified nexthop. The distance can be specified as well if desired.

ip mroute A.B.C.D/M INTERFACE (1-255)¶: Insert into the Multicast Rib Route A.B.C.D/M using the specified INTERFACE. The distance can be specified as well if desired.

Show PIM Information¶

All PIM show commands are vrf aware and typically allow you to insert a specified vrf command if information is desired about a specific vrf. If no vrf is specified then the default vrf is assumed. Finally the special keyword ‘all’ allows you to look at all vrfs for the command. Naming a vrf ‘all’ will cause great confusion.

show ip igmp interface¶: Display IGMP interface information.

show ip igmp join¶: Display IGMP static join information.

show ip igmp groups¶: Display IGMP groups information.

show ip igmp groups retransmissions¶: Display IGMP group retransmission information.

show ip igmp sources¶: Display IGMP sources information.

show ip igmp sources retransmissions¶: Display IGMP source retransmission information.

show ip igmp statistics¶: Display IGMP statistics information.

show ip multicast¶: Display various information about the interfaces used in this pim instance.

show ip mroute [vrf NAME] [A.B.C.D [A.B.C.D]] [fill] [json]¶: Display information about installed into the kernel S,G mroutes. If one address is specified we assume it is the Group we are interested in displaying data on. If the second address is specified then it is Source Group. The keyword fill says to fill in all assumed data for test/data gathering purposes.

show ip mroute count¶: Display information about installed into the kernel S,G mroutes and in addition display data about packet flow for the mroutes.

show ip mroute summary¶: Display total number of S,G mroutes and number of S,G mroutes installed into the kernel.

show ip pim assert¶: Display information about asserts in the PIM system for S,G mroutes.

show ip pim assert-internal¶: Display internal assert state for S,G mroutes

show ip pim assert-metric¶: Display metric information about assert state for S,G mroutes

show ip pim assert-winner-metric¶: Display winner metric for assert state for S,G mroutes

show ip pim group-type¶: Display SSM group ranges.

show ip pim interface¶: Display information about interfaces PIM is using.

show ip pim join¶: Display information about PIM joins received. If one address is specified then we assume it is the Group we are interested in displaying data on. If the second address is specified then it is Source Group.

show ip pim local-membership¶: Display information about PIM interface local-membership.

show ip pim neighbor¶: Display information about PIM neighbors.

show ip pim nexthop¶: Display information about pim nexthops that are being used.

show ip pim nexthop-lookup¶: Display information about a S,G pair and how the RPF would be chosen. This is especially useful if there are ECMP’s available from the RPF lookup.

show ip pim rp-info¶: Display information about RP’s that are configured on this router.

show ip pim rpf¶: Display information about currently being used S,G’s and their RPF lookup information. Additionally display some statistics about what has been happening on the router.

show ip pim secondary¶: Display information about an interface and all the secondary addresses associated with it.

show ip pim state¶: Display information about known S,G’s and incoming interface as well as the OIL and how they were chosen.

show ip pim upstream¶: Display upstream information about a S,G mroute. Allow the user to specify sub Source and Groups that we are only interested in.

show ip pim upstream-join-desired¶: Display upstream information for S,G’s and if we desire to join the multicast tree

show ip pim upstream-rpf¶: Display upstream information for S,G’s and the RPF data associated with them.

show ip pim bsr¶: Display current bsr, its uptime and last received bsm age.

show ip pim bsrp-info¶: Display group-to-rp mappings received from E-BSR.

show ip pim bsm-database¶: Display all fragments ofstored bootstrap message in user readable format.

show ip rpf¶: Display the multicast RIB created in zebra.

mtrace A.B.C.D [A.B.C.D]¶: Display multicast traceroute towards source, optionally for particular group.

PIM Debug Commands¶

The debugging subsystem for PIM behaves in accordance with how FRR handles debugging. You can specify debugging at the enable CLI mode as well as the configure CLI mode. If you specify debug commands in the configuration cli mode, the debug commands can be persistent across restarts of the FRR pimd if the config was written out.

debug igmp¶: This turns on debugging for IGMP protocol activity.

debug mtrace¶: This turns on debugging for mtrace protocol activity.

debug mroute¶: This turns on debugging for PIM interaction with kernel MFC cache.

debug pim events¶: This turns on debugging for PIM system events. Especially timers.

debug pim nht¶: This turns on debugging for PIM nexthop tracking. It will display information about RPF lookups and information about when a nexthop changes.

debug pim packet-dump¶: This turns on an extraordinary amount of data. Each pim packet sent and received is dumped for debugging purposes. This should be considered a developer only command.

debug pim packets¶: This turns on information about packet generation for sending and about packet handling from a received packet.

debug pim trace¶: This traces pim code and how it is running.

debug pim bsm¶: This turns on debugging for BSR message processing.

debug pim zebra¶: This gathers data about events from zebra that come up through the ZAPI.

PIM Clear Commands¶

Clear commands reset various variables.

clear ip interfaces¶: Reset interfaces.

clear ip igmp interfaces¶: Reset IGMP interfaces.

clear ip mroute¶: Reset multicast routes.

clear ip mroute [vrf NAME] count¶: When this command is issued, reset the counts of data shown for packet count, byte count and wrong interface to 0 and start count up from this spot.

clear ip pim interfaces¶: Reset PIM interfaces.

clear ip pim oil¶: Rescan PIM OIL (output interface list).

PIM EVPN configuration¶

To use PIM in the underlay for overlay BUM forwarding associate a multicast group with the L2 VNI. The actual configuration is based on your distribution. Here is an ifupdown2 example:

auto vx-10100
iface vx-10100
    vxlan-id 10100
    bridge-access 100
    vxlan-local-tunnelip 27.0.0.11
    vxlan-mcastgrp 239.1.1.100

Note

PIM will see the vxlan-mcastgrp configuration and auto configure state to properly forward BUM traffic.

PIM also needs to be configured in the underlay to allow the BUM MDT to be setup. This is existing PIM configuration:

Enable pim on the underlay L3 interface via the “ip pim” command.
Configure RPs for the BUM multicast group range.
Ensure the PIM is enabled on the lo of the VTEPs and the RP.

PBR¶

PBR is Policy Based Routing. This implementation supports a very simple interface to allow admins to influence routing on their router. At this time you can only match on destination and source prefixes for an incoming interface. At this point in time, this implementation will only work on Linux.

Starting PBR¶

Default configuration file for pbrd is pbrd.conf. The typical location of pbrd.conf is /etc/frr/pbrd.conf.

If the user is using integrated config, then pbrd.conf need not be present and the frr.conf is read instead.

PBR supports all the common FRR daemon start options which are documented elsewhere.

Nexthop Groups¶

Nexthop groups are a way to encapsulate ECMP information together. It’s a listing of ECMP nexthops used to forward packets for when a pbr-map is matched.

nexthop-group NAME¶: Create a nexthop-group with an associated NAME. This will put you into a sub-mode where you can specify individual nexthops. To exit this mode type exit or end as per normal conventions for leaving a sub-mode.

nexthop [A.B.C.D|X:X::X:XX] [interface] [nexthop-vrf NAME] [label LABELS]¶: Create a v4 or v6 nexthop. All normal rules for creating nexthops that you are used to are allowed here. The syntax was intentionally kept the same as creating nexthops as you would for static routes.

[no] pbr table range (10000-4294966272) (10000-4294966272)¶: Set or unset the range used to assign numeric table ID’s to new nexthop-group tables. Existing tables will not be modified to fit in this range, so it is recommended to configure this before adding nexthop groups.

See also

PBR Details

Showing Nexthop Group Information¶

show pbr nexthop-groups [NAME]¶: Display information on a PBR nexthop-group. If NAME is omitted, all nexthop groups are shown.

PBR Maps¶

PBR maps are a way to group policies that we would like to apply to individual interfaces. These policies when applied are matched against incoming packets. If matched the nexthop-group or nexthop is used to forward the packets to the end destination.

pbr-map NAME seq (1-700)¶: Create a pbr-map with NAME and sequence number specified. This command puts you into a new submode for pbr-map specification. To exit this mode type exit or end as per normal conventions for leaving a sub-mode.

match src-ip PREFIX¶: When a incoming packet matches the source prefix specified, take the packet and forward according to the nexthops specified. This command accepts both v4 and v6 prefixes. This command is used in conjunction of the match dst-ip PREFIX command for matching.

match dst-ip PREFIX¶: When a incoming packet matches the destination prefix specified, take the packet and forward according to the nexthops specified. This command accepts both v4 and v6 prefixes. This command is used in conjunction of the match src-ip PREFIX command for matching.

match mark (1-4294967295)¶: Select the mark to match. This is a linux only command and if attempted on another platform it will be denied. This mark translates to the underlying ip rule …. fwmark XXXX command.

set nexthop-group NAME¶: Use the nexthop-group NAME as the place to forward packets when the match commands have matched a packet.

set nexthop [A.B.C.D|X:X::X:XX] [interface] [nexthop-vrf NAME]¶: Use this individual nexthop as the place to forward packets when the match commands have matched a packet.

set vrf unchanged|NAME¶

If unchanged is set, the rule will use the vrf table the interface is in as its lookup. If NAME is specified, the rule will use that vrf table as its lookup.

Not supported with NETNS VRF backend.

show pbr map [NAME] [detail]¶: Display pbr maps either all or by NAME. If detail is set, it will give information about the rules unique ID used internally and some extra debugging information about install state for the nexthop/nexthop group.

PBR Policy¶

After you have specified a PBR map, in order for it to be turned on, you must apply the PBR map to an interface. This policy application to an interface causes the policy to be installed into the kernel.

pbr-policy NAME¶: This command is available under interface sub-mode. This turns on the PBR map NAME and allows it to work properly.

PBR Details¶

Under the covers a PBR map is translated into two separate constructs in the Linux kernel.

The PBR map specified creates a ip rule … that is inserted into the Linux kernel that points to a table to use for forwarding once the rule matches.

The creation of a nexthop or nexthop-group is translated to a default route in a table with the nexthops specified as the nexthops for the default route.

RIP¶

RIP – Routing Information Protocol is widely deployed interior gateway protocol. RIP was developed in the 1970s at Xerox Labs as part of the XNS routing protocol. RIP is a distance-vector protocol and is based on the Bellman-Ford algorithms. As a distance-vector protocol, RIP router send updates to its neighbors periodically, thus allowing the convergence to a known topology. In each update, the distance to any given network will be broadcast to its neighboring router.

ripd supports RIP version 2 as described in RFC2453 and RIP version 1 as described in RFC1058.

Starting and Stopping ripd¶

The default configuration file name of ripd’s is ripd.conf. When invocation ripd searches directory /etc/frr. If ripd.conf is not there next search current directory.

RIP uses UDP port 520 to send and receive RIP packets. So the user must have the capability to bind the port, generally this means that the user must have superuser privileges. RIP protocol requires interface information maintained by zebra daemon. So running zebra is mandatory to run ripd. Thus minimum sequence for running RIP is like below:

# zebra -d
# ripd -d

Please note that zebra must be invoked before ripd.

To stop ripd. Please use::: kill cat /var/run/ripd.pid

Certain signals have special meanings to ripd.

Signal Action

SIGHUP Reload configuration file ripd.conf. All configurations are reset. All routes learned so far are cleared and removed from routing table.

SIGUSR1 Rotate the ripd logfile.

SIGINT SIGTERM Sweep all installed routes and gracefully terminate.

ripd invocation options. Common options that can be specified (Common Invocation Options).

RIP netmask¶

The netmask features of ripd support both version 1 and version 2 of RIP. Version 1 of RIP originally contained no netmask information. In RIP version 1, network classes were originally used to determine the size of the netmask. Class A networks use 8 bits of mask, Class B networks use 16 bits of masks, while Class C networks use 24 bits of mask. Today, the most widely used method of a network mask is assigned to the packet on the basis of the interface that received the packet. Version 2 of RIP supports a variable length subnet mask (VLSM). By extending the subnet mask, the mask can be divided and reused. Each subnet can be used for different purposes such as large to middle size LANs and WAN links. FRR ripd does not support the non-sequential netmasks that are included in RIP Version 2.

In a case of similar information with the same prefix and metric, the old information will be suppressed. Ripd does not currently support equal cost multipath routing.

RIP Configuration¶

router rip¶: The router rip command is necessary to enable RIP. To disable RIP, use the no router rip command. RIP must be enabled before carrying out any of the RIP commands.

no router rip¶: Disable RIP.

network NETWORK¶

no network NETWORK¶

Set the RIP enable interface by NETWORK. The interfaces which have addresses matching with NETWORK are enabled.

This group of commands either enables or disables RIP interfaces between certain numbers of a specified network address. For example, if the network for 10.0.0.0/24 is RIP enabled, this would result in all the addresses from 10.0.0.0 to 10.0.0.255 being enabled for RIP. The no network command will disable RIP for the specified network.

network IFNAME¶

no network IFNAME¶: Set a RIP enabled interface by IFNAME. Both the sending and receiving of RIP packets will be enabled on the port specified in the network ifname command. The no network ifname command will disable RIP on the specified interface.

neighbor A.B.C.D¶

no neighbor A.B.C.D¶

Specify RIP neighbor. When a neighbor doesn’t understand multicast, this command is used to specify neighbors. In some cases, not all routers will be able to understand multicasting, where packets are sent to a network or a group of addresses. In a situation where a neighbor cannot process multicast packets, it is necessary to establish a direct link between routers. The neighbor command allows the network administrator to specify a router as a RIP neighbor. The no neighbor a.b.c.d command will disable the RIP neighbor.

Below is very simple RIP configuration. Interface eth0 and interface which address match to 10.0.0.0/8 are RIP enabled.

!
router rip
 network 10.0.0.0/8
 network eth0
!

passive-interface (IFNAME|default)¶

no passive-interface IFNAME¶

This command sets the specified interface to passive mode. On passive mode interface, all receiving packets are processed as normal and ripd does not send either multicast or unicast RIP packets except to RIP neighbors specified with neighbor command. The interface may be specified as default to make ripd default to passive on all interfaces.

The default is to be passive on all interfaces.

ip split-horizon¶

no ip split-horizon¶: Control split-horizon on the interface. Default is ip split-horizon. If you don’t perform split-horizon on the interface, please specify no ip split-horizon.

RIP Version Control¶

RIP can be configured to send either Version 1 or Version 2 packets. The default is to send RIPv2 while accepting both RIPv1 and RIPv2 (and replying with packets of the appropriate version for REQUESTS / triggered updates). The version to receive and send can be specified globally, and further overridden on a per-interface basis if needs be for send and receive separately (see below).

It is important to note that RIPv1 cannot be authenticated. Further, if RIPv1 is enabled then RIP will reply to REQUEST packets, sending the state of its RIP routing table to any remote routers that ask on demand. For a more detailed discussion on the security implications of RIPv1 see RIP Authentication.

version VERSION¶

Set RIP version to accept for reads and send. VERSION can be either 1 or 1.

Disabling RIPv1 by specifying version 2 is STRONGLY encouraged, RIP Authentication. This may become the default in a future release.

Default: Send Version 2, and accept either version.

no version¶: Reset the global version setting back to the default.

ip rip send version VERSION¶

VERSION can be 1, 2, or 1 2.

This interface command overrides the global rip version setting, and selects which version of RIP to send packets with, for this interface specifically. Choice of RIP Version 1, RIP Version 2, or both versions. In the latter case, where 1 2 is specified, packets will be both broadcast and multicast.

Default: Send packets according to the global version (version 2)

ip rip receive version VERSION¶

VERSION can be 1, 2, or 1 2.

This interface command overrides the global rip version setting, and selects which versions of RIP packets will be accepted on this interface. Choice of RIP Version 1, RIP Version 2, or both.

Default: Accept packets according to the global setting (both 1 and 2).

How to Announce RIP route¶

redistribute kernel¶

redistribute kernel metric (0-16)¶

redistribute kernel route-map ROUTE-MAP¶

no redistribute kernel¶: redistribute kernel redistributes routing information from kernel route entries into the RIP tables. no redistribute kernel disables the routes.

redistribute static¶

redistribute static metric (0-16)¶

redistribute static route-map ROUTE-MAP¶

no redistribute static¶: redistribute static redistributes routing information from static route entries into the RIP tables. no redistribute static disables the routes.

redistribute connected¶

redistribute connected metric (0-16)¶

redistribute connected route-map ROUTE-MAP¶

no redistribute connected¶: Redistribute connected routes into the RIP tables. no redistribute connected disables the connected routes in the RIP tables. This command redistribute connected of the interface which RIP disabled. The connected route on RIP enabled interface is announced by default.

redistribute ospf¶

redistribute ospf metric (0-16)¶

redistribute ospf route-map ROUTE-MAP¶

no redistribute ospf¶: redistribute ospf redistributes routing information from ospf route entries into the RIP tables. no redistribute ospf disables the routes.

redistribute bgp¶

redistribute bgp metric (0-16)¶

redistribute bgp route-map ROUTE-MAP¶

no redistribute bgp¶

redistribute bgp redistributes routing information from bgp route entries into the RIP tables. no redistribute bgp disables the routes.

If you want to specify RIP only static routes:

default-information originate¶

route A.B.C.D/M¶

no route A.B.C.D/M¶: This command is specific to FRR. The route command makes a static route only inside RIP. This command should be used only by advanced users who are particularly knowledgeable about the RIP protocol. In most cases, we recommend creating a static route in FRR and redistributing it in RIP using redistribute static.

Filtering RIP Routes¶

RIP routes can be filtered by a distribute-list.

distribute-list ACCESS_LIST DIRECT IFNAME¶

You can apply access lists to the interface with a distribute-list command. ACCESS_LIST is the access list name. DIRECT is in or out. If DIRECT is in the access list is applied to input packets.

The distribute-list command can be used to filter the RIP path. distribute-list can apply access-lists to a chosen interface. First, one should specify the access-list. Next, the name of the access-list is used in the distribute-list command. For example, in the following configuration eth0 will permit only the paths that match the route 10.0.0.0/8

!
router rip
 distribute-list private in eth0
!
access-list private permit 10 10.0.0.0/8
access-list private deny any
!

distribute-list can be applied to both incoming and outgoing data.

distribute-list prefix PREFIX_LIST (in|out) IFNAME¶: You can apply prefix lists to the interface with a distribute-list command. PREFIX_LIST is the prefix list name. Next is the direction of in or out. If DIRECT is in the access list is applied to input packets.

RIP Metric Manipulation¶

RIP metric is a value for distance for the network. Usually ripd increment the metric when the network information is received. Redistributed routes’ metric is set to 1.

default-metric (1-16)¶

no default-metric (1-16)¶: This command modifies the default metric value for redistributed routes. The default value is 1. This command does not affect connected route even if it is redistributed by redistribute connected. To modify connected route’s metric value, please use redistribute connected metric or route-map. offset-list also affects connected routes.

offset-list ACCESS-LIST (in|out)¶

offset-list ACCESS-LIST (in|out) IFNAME¶

RIP distance¶

Distance value is used in zebra daemon. Default RIP distance is 120.

distance (1-255)¶

no distance (1-255)¶: Set default RIP distance to specified value.

distance (1-255) A.B.C.D/M¶

no distance (1-255) A.B.C.D/M¶: Set default RIP distance to specified value when the route’s source IP address matches the specified prefix.

distance (1-255) A.B.C.D/M ACCESS-LIST¶

no distance (1-255) A.B.C.D/M ACCESS-LIST¶: Set default RIP distance to specified value when the route’s source IP address matches the specified prefix and the specified access-list.

RIP route-map¶

Usage of ripd’s route-map support.

Optional argument route-map MAP_NAME can be added to each redistribute statement.

redistribute static [route-map MAP_NAME]
redistribute connected [route-map MAP_NAME]
.....

Cisco applies route-map _before_ routes will exported to rip route table. In current FRR’s test implementation, ripd applies route-map after routes are listed in the route table and before routes will be announced to an interface (something like output filter). I think it is not so clear, but it is draft and it may be changed at future.

Route-map statement (Route Maps) is needed to use route-map functionality.

match interface WORD¶: This command match to incoming interface. Notation of this match is different from Cisco. Cisco uses a list of interfaces - NAME1 NAME2 … NAMEN. Ripd allows only one name (maybe will change in the future). Next - Cisco means interface which includes next-hop of routes (it is somewhat similar to “ip next-hop” statement). Ripd means interface where this route will be sent. This difference is because “next-hop” of same routes which sends to different interfaces must be different. Maybe it’d be better to made new matches - say “match interface-out NAME” or something like that.

match ip address WORD¶

match ip address prefix-list WORD¶: Match if route destination is permitted by access-list.

match ip next-hop WORD¶

match ip next-hop prefix-list WORD¶: Match if route next-hop (meaning next-hop listed in the rip route-table as displayed by “show ip rip”) is permitted by access-list.

match metric (0-4294967295)¶: This command match to the metric value of RIP updates. For other protocol compatibility metric range is shown as (0-4294967295). But for RIP protocol only the value range (0-16) make sense.

set ip next-hop A.B.C.D¶: This command set next hop value in RIPv2 protocol. This command does not affect RIPv1 because there is no next hop field in the packet.

set metric (0-4294967295)¶: Set a metric for matched route when sending announcement. The metric value range is very large for compatibility with other protocols. For RIP, valid metric values are from 1 to 16.

RIP Authentication¶

RIPv2 allows packets to be authenticated via either an insecure plain text password, included with the packet, or via a more secure MD5 based HMAC, RIPv1 can not be authenticated at all, thus when authentication is configured ripd will discard routing updates received via RIPv1 packets.

However, unless RIPv1 reception is disabled entirely, RIP Version Control, RIPv1 REQUEST packets which are received, which query the router for routing information, will still be honoured by ripd, and ripd WILL reply to such packets. This allows ripd to honour such REQUESTs (which sometimes is used by old equipment and very simple devices to bootstrap their default route), while still providing security for route updates which are received.

In short: Enabling authentication prevents routes being updated by unauthenticated remote routers, but still can allow routes (I.e. the entire RIP routing table) to be queried remotely, potentially by anyone on the internet, via RIPv1.

To prevent such unauthenticated querying of routes disable RIPv1, RIP Version Control.

ip rip authentication mode md5¶

no ip rip authentication mode md5¶: Set the interface with RIPv2 MD5 authentication.

ip rip authentication mode text¶

no ip rip authentication mode text¶: Set the interface with RIPv2 simple password authentication.

ip rip authentication string STRING¶

no ip rip authentication string STRING¶: RIP version 2 has simple text authentication. This command sets authentication string. The string must be shorter than 16 characters.

ip rip authentication key-chain KEY-CHAIN¶

no ip rip authentication key-chain KEY-CHAIN¶

Specify Keyed MD5 chain.

!
key chain test
 key 1
  key-string test
!
interface eth1
 ip rip authentication mode md5
 ip rip authentication key-chain test
!

RIP Timers¶

timers basic UPDATE TIMEOUT GARBAGE¶

RIP protocol has several timers. User can configure those timers’ values by timers basic command.

The default settings for the timers are as follows:

The update timer is 30 seconds. Every update timer seconds, the RIP process is awakened to send an unsolicited Response message containing the complete routing table to all neighboring RIP routers.
The timeout timer is 180 seconds. Upon expiration of the timeout, the route is no longer valid; however, it is retained in the routing table for a short time so that neighbors can be notified that the route has been dropped.
The garbage collect timer is 120 seconds. Upon expiration of the garbage-collection timer, the route is finally removed from the routing table.

The timers basic command allows the the default values of the timers listed above to be changed.

no timers basic¶: The no timers basic command will reset the timers to the default settings listed above.

Show RIP Information¶

To display RIP routes.

show ip rip¶: Show RIP routes.

The command displays all RIP routes. For routes that are received through RIP, this command will display the time the packet was sent and the tag information. This command will also display this information for routes redistributed into RIP.

show ip rip status¶: The command displays current RIP status. It includes RIP timer, filtering, version, RIP enabled interface and RIP peer information.

ripd> **show ip rip status**
Routing Protocol is "rip"
  Sending updates every 30 seconds with +/-50%, next due in 35 seconds
  Timeout after 180 seconds, garbage collect after 120 seconds
  Outgoing update filter list for all interface is not set
  Incoming update filter list for all interface is not set
  Default redistribution metric is 1
  Redistributing: kernel connected
  Default version control: send version 2, receive version 2
    Interface  Send  Recv
  Routing for Networks:
    eth0
    eth1
    1.1.1.1
    203.181.89.241
  Routing Information Sources:
    Gateway    BadPackets BadRoutes  Distance Last Update

RIP Debug Commands¶

Debug for RIP protocol.

debug rip events¶: Shows RIP events. Sending and receiving packets, timers, and changes in interfaces are events shown with ripd.

debug rip packet¶: Shows display detailed information about the RIP packets. The origin and port number of the packet as well as a packet dump is shown.

debug rip zebra¶: This command will show the communication between ripd and zebra. The main information will include addition and deletion of paths to the kernel and the sending and receiving of interface information.

show debugging rip¶: Shows all information currently set for ripd debug.

RIPng¶

ripngd supports the RIPng protocol as described in RFC 2080. It’s an IPv6 reincarnation of the RIP protocol.

Invoking ripngd¶

There are no ripngd specific invocation options. Common options can be specified (Common Invocation Options).

ripngd Configuration¶

Currently ripngd supports the following commands:

router ripng¶: Enable RIPng.

flush_timer TIME¶: Set flush timer.

network NETWORK¶: Set RIPng enabled interface by NETWORK.

network IFNAME¶: Set RIPng enabled interface by IFNAME.

route NETWORK¶: Set RIPng static routing announcement of NETWORK.

router zebra¶: This command is the default and does not appear in the configuration. With this statement, RIPng routes go to the zebra daemon.

ripngd Terminal Mode Commands¶

show ip ripng¶

show debugging ripng¶

debug ripng events¶

debug ripng packet¶

debug ripng zebra¶

ripngd Filtering Commands¶

distribute-list ACCESS_LIST (in|out) IFNAME¶

You can apply an access-list to the interface using the distribute-list command. ACCESS_LIST is an access-list name. direct is in or out. If direct is in, the access-list is applied only to incoming packets.:

distribute-list local-only out sit1

SHARP¶

SHARP is a daemon that provides miscellaneous functionality used for testing FRR and creating proof-of-concept labs.

Starting SHARP¶

Default configuration file for sharpd is sharpd.conf. The typical location of sharpd.conf is /etc/frr/sharpd.conf.

If the user is using integrated config, then sharpd.conf need not be present and the frr.conf is read instead.

SHARP supports all the common FRR daemon start options which are documented elsewhere.

Using SHARP¶

All sharp commands are under the enable node and preceded by the sharp keyword. At present, no sharp commands will be preserved in the config.

sharp install routes A.B.C.D <nexthop <E.F.G.H|X:X::X:X>|nexthop-group NAME> (1-1000000) [instance (0-255)] [repeat (2-1000)]¶: Install up to 1,000,000 (one million) /32 routes starting at A.B.C.D with specified nexthop E.F.G.H or X:X::X:X. The nexthop is a NEXTHOP_TYPE_IPV4 or NEXTHOP_TYPE_IPV6 and must be reachable to be installed into the kernel. Alternatively a nexthop-group NAME can be specified and used as the nexthops. The routes are installed into zebra as ZEBRA_ROUTE_SHARP and can be used as part of a normal route redistribution. Route installation time is noted in the debug log. When zebra successfully installs a route into the kernel and SHARP receives success notifications for all routes this is logged as well. Instance (0-255) if specified causes the routes to be installed in a different instance. If repeat is used then we will install/uninstall the routes the number of times specified.

sharp remove routes A.B.C.D (1-1000000)¶: Remove up to 1,000,000 (one million) /32 routes starting at A.B.C.D. The routes are removed from zebra. Route deletion start is noted in the debug log and when all routes have been successfully deleted the debug log will be updated with this information as well.

sharp data route¶: Allow end user doing route install and deletion to get timing information from the vty or vtysh instead of having to read the log file. This command is informational only and you should look at sharp_vty.c for explanation of the output as that it may change.

sharp label <ipv4|ipv6> vrf NAME label (0-1000000)¶: Install a label into the kernel that causes the specified vrf NAME table to be used for pop and forward operations when the specified label is seen.

[no] sharp watch <nexthop <A.B.C.D|X:X::X:X>|import <A.B.C.D/M:X:X::X:X/M> [connected]¶: Instruct zebra to monitor and notify sharp when the specified nexthop is changed. The notification from zebra is written into the debug log. The nexthop or import choice chooses the type of nexthop we are asking zebra to watch for us. This choice affects zebra’s decision on what matches. Connected tells zebra whether or not that we want the route matched against to be a static or connected route. The no form of the command obviously turns this watching off.

sharp data nexthop¶: Allow end user to dump associated data with the nexthop tracking that may have been turned on.

STATIC¶

STATIC is a daemon that handles the installation and deletion of static routes.

Starting STATIC¶

Default configuration file for staticd is staticd.conf. The typical location of staticd.conf is /etc/frr/staticd.conf.

If the user is using integrated config, then staticd.conf need not be present and the frr.conf is read instead.

If the user has not fully upgraded to using the staticd.conf and still has a non-integrated config with zebra.conf holding the static routes, staticd will read in the zebrad.conf as a backup.

STATIC supports all the common FRR daemon start options which are documented elsewhere.

Static Route Commands¶

Static routing is a very fundamental feature of routing technology. It defines a static prefix and gateway.

ip route NETWORK GATEWAY table TABLENO nexthop-vrf VRFNAME DISTANCE vrf VRFNAME¶

ipv6 route NETWORK from SRCPREFIX GATEWAY table TABLENO nexthop-vrf VRFNAME DISTANCE vrf VRFNAME¶: NETWORK is destination prefix with a valid v4 or v6 network based upon initial form of the command. GATEWAY is gateway for the prefix it currently must match the v4 or v6 route type specified at the start of the command. GATEWAY can also be treated as an interface name. If the interface name is null0 then zebra installs a blackhole route. TABLENO is an optional parameter for namespaces that allows you to create the route in a specified table associated with the vrf namespace. table will be rejected if you are not using namespace based vrfs. nexthop-vrf allows you to create a leaked route with a nexthop in the specified VRFNAME vrf VRFNAME allows you to create the route in a specified vrf. nexthop-vrf cannot be currently used with namespace based vrfs currently as well. The v6 variant allows the installation of a static source-specific route with the SRCPREFIX sub command. These routes are currently supported on Linux operating systems only, and perform AND matching on packet’s destination and source addresses in the kernel’s forwarding path. Note that destination longest-prefix match is “more important” than source LPM, e.g. 2001:db8:1::/64 from 2001:db8::/48 will win over 2001:db8::/48 from 2001:db8:1::/64 if both match.

Multiple nexthop static route¶

To create multiple nexthops to the same NETWORK, just reenter the same network statement with different nexthop information.

ip route 10.0.0.1/32 10.0.0.2
ip route 10.0.0.1/32 10.0.0.3
ip route 10.0.0.1/32 eth0

If there is no route to 10.0.0.2 and 10.0.0.3, and interface eth0 is reachable, then the last route is installed into the kernel.

If zebra has been compiled with multipath support, and both 10.0.0.2 and 10.0.0.3 are reachable, zebra will install a multipath route via both nexthops, if the platform supports this.

router> show ip route
S>  10.0.0.1/32 [1/0] via 10.0.0.2 inactive
    via 10.0.0.3 inactive
  *       is directly connected, eth0

ip route 10.0.0.0/8 10.0.0.2
ip route 10.0.0.0/8 10.0.0.3
ip route 10.0.0.0/8 null0 255

This will install a multihop route via the specified next-hops if they are reachable, as well as a high-distance blackhole route, which can be useful to prevent traffic destined for a prefix to match less-specific routes (e.g. default) should the specified gateways not be reachable. E.g.:

router> show ip route 10.0.0.0/8
Routing entry for 10.0.0.0/8
  Known via "static", distance 1, metric 0
    10.0.0.2 inactive
    10.0.0.3 inactive

Routing entry for 10.0.0.0/8
  Known via "static", distance 255, metric 0
    directly connected, Null0

Also, if the user wants to configure a static route for a specific VRF, then a specific VRF configuration mode is available. After entering into that mode with vrf VRF the user can enter the same route command as before, but this time, the route command will apply to the VRF.

# case with VRF
configure
vrf r1-cust1
 ip route 10.0.0.0/24 10.0.0.2
exit-vrf

VNC and VNC-GW¶

This chapter describes how to use VNC services, including NVA and VNC-GW functions. Background information on NVAs, NVE s, UN s, and VN is available from the IETF. VNC-GW s support the import/export of routing information between VNC and CE routers operating within a VN. Both IP/Layer 3 (L3) VNs, and IP with Ethernet/Layer 2 (L2) VNs are supported.

BGP, with IP VPNs and Tunnel Encapsulation, is used to distribute VN information between NVAs. BGP based IP VPN support is defined in RFC 4364, and RFC 4659. Encapsulation information is provided via the Tunnel Encapsulation Attribute, RFC 5512.

The protocol that is used to communicate routing and Ethernet / Layer 2 (L2) forwarding information between NVAs and NVEs is referred to as the Remote Forwarder Protocol (RFP). OpenFlow is an example RFP. Specific RFP implementations may choose to implement either a hard-state or soft-state prefix and address registration model. To support a soft-state refresh model, a lifetime in seconds is associated with all registrations and responses.

The chapter also provides sample configurations for basic example scenarios.

Configuring VNC¶

Virtual Network Control (VNC) service configuration commands appear in the router bgp section of the BGPD configuration file (Miscellaneous Configuration Examples). The commands are broken down into the following areas:

General VNC configuration applies to general VNC operation and is primarily used to control the method used to advertise tunnel information.
Remote Forwarder Protocol (RFP) configuration relates to the protocol used between NVAs and NVEs.
VNC Defaults provides default parameters for registered NVEs.
VNC NVE Group provides for configuration of a specific set of registered NVEs and overrides default parameters.
Redistribution and Export control VNC-GW operation, i.e., the import/export of routing information between VNC and customer edge routers (CE s) operating within a VN.

General VNC Configuration¶

VNC Defaults Configuration¶

The VNC Defaults section allows the user to specify default values for configuration parameters for all registered NVEs. Default values are overridden by VNC NVE Group Configuration.

vnc defaults¶

Enter VNC configuration mode for specifying VNC default behaviors. Use exit-vnc to leave VNC configuration mode. vnc defaults is optional.

vnc defaults
... various VNC defaults
exit-vnc

These are the statements that can appear between vnc defaults and exit-vnc. Documentation for these statements is given in VNC NVE Group Configuration.

rt import RT-LIST
rt export RT-LIST
rt both RT-LIST
rd ROUTE-DISTINGUISHER
l2rd NVE-ID-VALUE
response-lifetime LIFETIME|infinite
export bgp|zebra route-map MAP-NAME
export bgp|zebra no route-map

exit-vnc¶: Exit VNC configuration mode.

VNC NVE Group Configuration¶

A NVE Group corresponds to a specific set of NVEs. A Client NVE is assigned to an NVE Group based on whether there is a match for either its virtual or underlay network address against the VN and/or UN address prefixes specified in the NVE Group definition. When an NVE Group definition specifies both VN and UN address prefixes, then an NVE must match both prefixes in order to be assigned to the NVE Group. In the event that multiple NVE Groups match based on VN and/or UN addresses, the NVE is assigned to the first NVE Group listed in the configuration. If an NVE is not assigned to an NVE Group, its messages will be ignored.

Configuration values specified for an NVE group apply to all member NVEs and override configuration values specified in the VNC Defaults section.

At least one `nve-group` is mandatory for useful VNC operation.

vnc nve-group NAME¶

Enter VNC configuration mode for defining the NVE group name. Use exit or exit-vnc to exit group configuration mode.

vnc nve-group group1
... configuration commands
exit-vnc

no vnc nve-group NAME¶

Delete the NVE group named name.

The following statements are valid in an NVE group definition:

l2rd NVE-ID-VALUE¶

Set the value used to distinguish NVEs connected to the same physical Ethernet segment (i.e., at the same location) [1].

The nve-id subfield may be specified as either a literal value in the range 1-255, or it may be specified as auto:vn, which means to use the least-significant octet of the originating NVE’s VN address.

prefix vn|un A.B.C.D/M|X:X::X:X/M¶

Specify the matching prefix for this NVE group by either virtual-network address (vn) or underlay-network address (un). Either or both virtual-network and underlay-network prefixes may be specified. Subsequent virtual-network or underlay-network values within a vnc nve-group exit-vnc block override their respective previous values.

These prefixes are used only for determining assignments of NVEs to NVE Groups.

rd ROUTE-DISTINGUISHER¶

Specify the route distinguisher for routes advertised via BGP VPNs. The route distinguisher must be in one of these forms:

IPv4-address:two-byte-integer
four-byte-autonomous-system-number:two-byte-integer
two-byte-autonomous-system-number:four-byte-integer
auto:vn:two-byte-integer

Routes originated by NVEs in the NVE group will use the group’s specified route-distinguisher when they are advertised via BGP. If the auto form is specified, it means that a matching NVE has its RD set to rd_type=IP=1:IPv4-address=VN-address:two-byte-integer, for IPv4 VN addresses and rd_type=IP=1:IPv4-address=Last-four-bytes-of-VN-address:two-byte-integer, for IPv6 VN addresses.

If the NVE group definition does not specify a route-distinguisher, then the default route-distinguisher is used. If neither a group nor a default route-distinguisher is configured, then the advertised RD is set to two-byte-autonomous-system-number=0:four-byte-integer=0.

response-lifetime LIFETIME|infinite¶

Specify the response lifetime, in seconds, to be included in RFP response messages sent to NVEs. If the value ‘infinite’ is given, an infinite lifetime will be used.

Note that this parameter is not the same as the lifetime supplied by NVEs in RFP registration messages. This parameter does not affect the lifetime value attached to routes sent by this server via BGP.

If the NVE group definition does not specify a response-lifetime, the default response-lifetime will be used. If neither a group nor a default response-lifetime is configured, the value 3600 will be used. The maximum response lifetime is 2147483647.

rt export RT-LIST¶

rt import RT-LIST¶

rt both RT-LIST¶

Specify route target import and export lists. rt-list is a space-separated list of route targets, each element of which is in one of the following forms:

IPv4-address:two-byte-integer
four-byte-autonomous-system-number:two-byte-integer
two-byte-autonomous-system-number:four-byte-integer

The first form, rt export, specifies an export rt-list. The export rt-list will be attached to routes originated by NVEs in the NVE group when they are advertised via BGP. If the NVE group definition does not specify an export rt-list, then the default export rt-list is used. If neither a group nor a default export rt-list is configured, then no RT list will be sent; in turn, these routes will probably not be processed by receiving NVAs.

The second form, rt import specifies an import rt-list, which is a filter for incoming routes. In order to be made available to NVEs in the group, incoming BGP VPN routes must have RT lists that have at least one route target in common with the group’s import rt-list.

If the NVE group definition does not specify an import filter, then the default import rt-list is used. If neither a group nor a default import rt-list is configured, there can be no RT intersections when receiving BGP routes and therefore no incoming BGP routes will be processed for the group.

The third, rt both, is a shorthand way of specifying both lists simultaneously, and is equivalent to rt export `rt-list` followed by rt import `rt-list`.

export bgp|zebra route-map MAP-NAME¶: Specify that the named route-map should be applied to routes being exported to bgp or zebra. This parameter is used in conjunction with Configuring Export of Routes to Other Routing Protocols. This item is optional.

export bgp|zebra no route-map¶: Specify that no route-map should be applied to routes being exported to bgp or zebra. This parameter is used in conjunction with Configuring Export of Routes to Other Routing Protocols. This item is optional.

export bgp|zebra ipv4|ipv6 prefix-list LIST-NAME¶: Specify that the named prefix-list filter should be applied to routes being exported to bgp or zebra. Prefix-lists for ipv4 and ipv6 are independent of each other. This parameter is used in conjunction with Configuring Export of Routes to Other Routing Protocols. This item is optional.

export bgp|zebra no ipv4|ipv6 prefix-list¶: Specify that no prefix-list filter should be applied to routes being exported to bgp or zebra. This parameter is used in conjunction with Configuring Export of Routes to Other Routing Protocols. This item is optional.

VNC L2 Group Configuration¶

The route targets advertised with prefixes and addresses registered by an NVE are determined based on the NVE’s associated VNC NVE Group Configuration, VNC NVE Group Configuration. Layer 2 (L2) Groups are used to override the route targets for an NVE’s Ethernet registrations based on the Logical Network Identifier and label value. A Logical Network Identifier is used to uniquely identify a logical Ethernet segment and is conceptually similar to the Ethernet Segment Identifier defined in RFC 7432. Both the Logical Network Identifier and Label are passed to VNC via RFP prefix and address registration.

Note that a corresponding NVE group configuration must be present, and that other NVE associated configuration information, notably RD, is not impacted by L2 Group Configuration.

vnc l2-group NAME¶

Enter VNC configuration mode for defining the L2 group name. Use exit or exit-vnc to exit group configuration mode.

vnc l2-group group1
  ... configuration commands
exit-vnc

no vnc l2-group NAME¶: Delete the L2 group named name.

The following statements are valid in a L2 group definition:

logical-network-id VALUE¶: Define the Logical Network Identifier with a value in the range of 0-4294967295 that identifies the logical Ethernet segment.

labels LABEL-LIST¶

no labels LABEL-LIST¶: Add or remove labels associated with the group. label-list is a space separated list of label values in the range of 0-1048575.

rt import RT-TARGET¶

rt export RT-TARGET¶

rt both RT-TARGET¶: Specify the route target import and export value associated with the group. A complete definition of these parameters is given above, VNC NVE Group Configuration.

Configuring Redistribution of Routes from Other Routing Protocols¶

Routes from other protocols (including BGP) can be provided to VNC (both for RFP and for redistribution via BGP) from three sources: the zebra kernel routing process; directly from the main (default) unicast BGP RIB; or directly from a designated BGP unicast exterior routing RIB instance.

The protocol named in the vnc redistribute command indicates the route source: bgp-direct routes come directly from the main (default) unicast BGP RIB and are available for RFP and are redistributed via BGP; bgp-direct-to-nve-groups routes come directly from a designated BGP unicast routing RIB and are made available only to RFP; and routes from other protocols come from the zebra kernel routing process. Note that the zebra process does not need to be active if only bgp-direct or bgp-direct-to-nve-groups routes are used.

zebra routes¶

Routes originating from protocols other than BGP must be obtained via the zebra routing process. Redistribution of these routes into VNC does not support policy mechanisms such as prefix-lists or route-maps.

bgp-direct routes¶

bgp-direct redistribution supports policy via prefix lists and route-maps. This policy is applied to incoming original unicast routes before the redistribution translations (described below) are performed.

Redistribution of bgp-direct routes is performed in one of three possible modes: plain, nve-group, or resolve-nve. The default mode is plain. These modes indicate the kind of translations applied to routes before they are added to the VNC RIB.

In plain mode, the route’s next hop is unchanged and the RD is set based on the next hop. For bgp-direct redistribution, the following translations are performed:

The VN address is set to the original unicast route’s next hop address.
The UN address is NOT set. (VN->UN mapping will occur via ENCAP route or attribute, based on vnc advertise-un-method setting, generated by the RFP registration of the actual NVE)
The RD is set to as if auto:vn:0 were specified (i.e., rd_type=IP=1:IPv4-address=VN-address:two-byte-integer=0)
The RT list is included in the extended community list copied from the original unicast route (i.e., it must be set in the original unicast route).

In nve-group mode, routes are registered with VNC as if they came from an NVE in the nve-group designated in the vnc redistribute nve-group command. The following translations are performed:

The next hop/VN address is set to the VN prefix configured for the redistribute nve-group.
The UN address is set to the UN prefix configured for the redistribute nve-group.
The RD is set to the RD configured for the redistribute nve-group.
The RT list is set to the RT list configured for the redistribute nve-group. If bgp-direct routes are being redistributed, any extended communities present in the original unicast route will also be included.

In resolve-nve mode, the next hop of the original BGP route is typically the address of an NVE connected router (CE) connected by one or more NVEs. Each of the connected NVEs will register, via RFP, a VNC host route to the CE. This mode may be though of as a mechanism to proxy RFP registrations of BGP unicast routes on behalf of registering NVEs.

Multiple copies of the BGP route, one per matching NVE host route, will be added to VNC. In other words, for a given BGP unicast route, each instance of a RFP-registered host route to the unicast route’s next hop will result in an instance of an imported VNC route. Each such imported VNC route will have a prefix equal to the original BGP unicast route’s prefix, and a next hop equal to the next hop of the matching RFP-registered host route. If there is no RFP-registered host route to the next hop of the BGP unicast route, no corresponding VNC route will be imported.

The following translations are applied:

The Next Hop is set to the next hop of the NVE route (i.e., the VN address of the NVE).
The extended community list in the new route is set to the union of:
Any extended communities in the original BGP route
- Any extended communities in the NVE route
- An added route-origin extended community with the next hop of the original BGP route is added to the new route. The value of the local administrator field defaults 5226 but may be configured by the user via the roo-ec-local-admin parameter.
The Tunnel Encapsulation attribute is set to the value of the Tunnel Encapsulation attribute of the NVE route, if any.

bgp-direct-to-nve-groups routes¶

Unicast routes from the main or a designated instance of BGP may be redistributed to VNC as bgp-direct-to-nve-groups routes. These routes are NOT announced via BGP, but they are made available for local RFP lookup in response to queries from NVEs.

A non-main/default BGP instance is configured using the router bgp AS view NAME command as described elsewhere in this document.

In order for a route in the unicast BGP RIB to be made available to a querying NVE, there must already be, available to that NVE, an (interior) VNC route matching the next hop address of the unicast route. When the unicast route is provided to the NVE, its next hop is replaced by the next hop of the corresponding NVE. If there are multiple longest-prefix-match VNC routes, the unicast route will be replicated for each.

There is currently no policy (prefix-list or route-map) support for bgp-direct-to-nve-groups routes.

Redistribution Command Syntax¶

vnc redistribute ipv4|ipv6 bgp|bgp-direct|ipv6 bgp-direct-to-nve-groups|connected|kernel|ospf|rip|static¶

vnc redistribute ipv4|ipv6 bgp-direct-to-nve-groups view VIEWNAME¶

no vnc redistribute ipv4|ipv6 bgp|bgp-direct|bgp-direct-to-nve-groups|connected|kernel|ospf|rip|static¶: Import (or do not import) prefixes from another routing protocols. Specify both the address family to import (ipv4 or ipv6) and the protocol (bgp, bgp-direct, bgp-direct-to-nve-groups, connected, kernel, ospf, rip, or static). Repeat this statement as needed for each combination of address family and routing protocol. Prefixes from protocol bgp-direct are imported from unicast BGP in the same bgpd process. Prefixes from all other protocols (including bgp) are imported via the zebra kernel routing process.

vnc redistribute mode plain|nve-group|resolve-nve¶: Redistribute routes from other protocols into VNC using the specified mode. Not all combinations of modes and protocols are supported.

vnc redistribute nve-group GROUP-NAME¶

no vnc redistribute nve-group GROUP-NAME¶

When using nve-group mode, assign (or do not assign) the NVE group group-name to routes redistributed from another routing protocol. group-name must be configured using vnc nve-group.

The VN and UN prefixes of the nve-group must both be configured, and each prefix must be specified as a full-length (/32 for IPv4, /128 for IPv6) prefix.

vnc redistribute lifetime LIFETIME|infinite¶: Assign a registration lifetime, either lifetime seconds or infinite, to prefixes redistributed from other routing protocols as if they had been received via RFP registration messages from an NVE. lifetime can be any integer between 1 and 4294967295, inclusive.

vnc redistribute resolve-nve roo-ec-local-admin 0-65536¶: Assign a value to the local-administrator subfield used in the Route Origin extended community that is assigned to routes exported under the resolve-nve mode. The default value is 5226.

The following four prefix-list and route-map commands may be specified in the context of an nve-group or not. If they are specified in the context of an nve-group, they apply only if the redistribution mode is nve-group, and then only for routes being redistributed from bgp-direct. If they are specified outside the context of an nve-group, then they apply only for redistribution modes plain and resolve-nve, and then only for routes being redistributed from bgp-direct.

vnc redistribute bgp-direct (ipv4|ipv6) prefix-list LIST-NAME¶: When redistributing bgp-direct routes, specifies that the named prefix-list should be applied.

vnc redistribute bgp-direct no (ipv4|ipv6) prefix-list¶: When redistributing bgp-direct routes, specifies that no prefix-list should be applied.

vnc redistribute bgp-direct route-map MAP-NAME¶: When redistributing bgp-direct routes, specifies that the named route-map should be applied.

vnc redistribute bgp-direct no route-map¶: When redistributing bgp-direct routes, specifies that no route-map should be applied.

Configuring Export of Routes to Other Routing Protocols¶

Routes from VNC (both for RFP and for redistribution via BGP) can be provided to other protocols, either via zebra or directly to BGP.

It is important to note that when exporting routes to other protocols, the downstream protocol must also be configured to import the routes. For example, when VNC routes are exported to unicast BGP, the BGP configuration must include a corresponding redistribute vnc-direct statement.

export bgp|zebra mode none|group-nve|registering-nve|ce¶

Specify how routes should be exported to bgp or zebra. If the mode is none, routes are not exported. If the mode is group-nve, routes are exported according to nve-group or vrf-policy group configuration (VNC NVE Group Configuration): if a group is configured to allow export, then each prefix visible to the group is exported with next hops set to the currently-registered NVEs. If the mode is registering-nve, then all VNC routes are exported with their original next hops. If the mode is ce, only VNC routes that have an NVE connected CE Router encoded in a Route Origin Extended Community are exported. This extended community must have an administrative value that matches the configured roo-ec-local-admin value. The next hop of the exported route is set to the encoded NVE connected CE Router.

The default for both bgp and zebra is mode none.

vnc export bgp|zebra group-nve group GROUP-NAME¶

vnc export bgp|zebra group-nve no group GROUP-NAME¶: When export mode is group-nve, export (or do not export) prefixes from the specified nve-group or vrf-policy group to unicast BGP or to zebra. Repeat this statement as needed for each nve-group to be exported. Each VNC prefix that is exported will result in N exported routes to the prefix, each with a next hop corresponding to one of the N NVEs currently associated with the nve-group.

Some commands have a special meaning under certain export modes.

export bgp|zebra ipv4|ipv6 prefix-list LIST-NAME

When export mode is ce or registering-nve, specifies that the named prefix-list should be applied to routes being exported to bgp or zebra. Prefix-lists for ipv4 and ipv6 are independent of each other.

export bgp|zebra no ipv4|ipv6 prefix-list

When export mode is ce or registering-nve, specifies that no prefix-list should be applied to routes being exported to bgp or zebra.

export bgp|zebra route-map MAP-NAME

When export mode is ce or registering-nve, specifies that the named route-map should be applied to routes being exported to bgp or zebra.

export bgp|zebra no route-map

When export mode is ce or registering-nve, specifies that no route-map should be applied to routes being exported to bgp or zebra.

When the export mode is group-nve, policy for exported routes is specified per-NVE-group or vrf-policy group inside a nve-group RFG-NAME block via the following commands(VNC NVE Group Configuration):

export bgp|zebra route-map MAP-NAME

This command is valid inside a nve-group RFG-NAME block. It specifies that the named route-map should be applied to routes being exported to bgp or zebra.

export bgp|zebra no route-map

This command is valid inside a nve-group RFG-NAME block. It specifies that no route-map should be applied to routes being exported to bgp or zebra.

export bgp|zebra ipv4|ipv6 prefix-list LIST-NAME

This command is valid inside a nve-group RFG-NAME block. It specifies that the named prefix-list filter should be applied to routes being exported to bgp or zebra. Prefix-lists for ipv4 and ipv6 are independent of each other.

export bgp|zebra no ipv4|ipv6 prefix-list

This command is valid inside a nve-group RFG-NAME block. It specifies that no prefix-list filter should be applied to routes being exported to bgp or zebra.

Manual Address Control¶

The commands in this section can be used to augment normal dynamic VNC. The add vnc commands can be used to manually add IP prefix or Ethernet MAC address forwarding information. The clear vnc commands can be used to remove manually and dynamically added information.

add vnc prefix (A.B.C.D/M|X:X::X:X/M) vn (A.B.C.D|X:X::X:X) un (A.B.C.D|X:X::X:X) [cost (0-255)] [lifetime (infinite|(1-4294967295))] [local-next-hop (A.B.C.D|X:X::X:X) [local-cost (0-255)]]¶: Register an IP prefix on behalf of the NVE identified by the VN and UN addresses. The cost parameter provides the administrative preference of the forwarding information for remote advertisement. If omitted, it defaults to 255 (lowest preference). The lifetime parameter identifies the period, in seconds, that the information remains valid. If omitted, it defaults to infinite. The optional local-next-hop parameter is used to configure a nexthop to be used by an NVE to reach the prefix via a locally connected CE router. This information remains local to the NVA, i.e., not passed to other NVAs, and is only passed to registered NVEs. When specified, it is also possible to provide a local-cost parameter to provide a forwarding preference. If omitted, it defaults to 255 (lowest preference).

add vnc mac xx:xx:xx:xx:xx:xx virtual-network-identifier (1-4294967295) vn (A.B.C.D|X:X::X:X) un (A.B.C.D|X:X::X:X) [prefix (A.B.C.D/M|X:X::X:X/M)] [cost (0-255)] [lifetime (infinite|(1-4294967295))]¶: Register a MAC address for a logical Ethernet (L2VPN) on behalf of the NVE identified by the VN and UN addresses. The optional prefix parameter is to support enable IP address mediation for the given prefix. The cost parameter provides the administrative preference of the forwarding information. If omitted, it defaults to 255. The lifetime parameter identifies the period, in seconds, that the information remains valid. If omitted, it defaults to infinite.

clear vnc prefix (*|A.B.C.D/M|X:X::X:X/M) (*|[(vn|un) (A.B.C.D|X:X::X:X|*) [(un|vn) (A.B.C.D|X:X::X:X|*)] [mac xx:xx:xx:xx:xx:xx] [local-next-hop (A.B.C.D|X:X::X:X)])¶: Delete the information identified by prefix, VN address, and UN address. Any or all of these parameters may be wildcarded to (potentially) match more than one registration. The optional mac parameter specifies a layer-2 MAC address that must match the registration(s) to be deleted. The optional local-next-hop parameter is used to delete specific local nexthop information.

clear vnc mac (*|xx:xx:xx:xx:xx:xx) virtual-network-identifier (*|(1-4294967295)) (*|[(vn|un) (A.B.C.D|X:X::X:X|*) [(un|vn) (A.B.C.D|X:X::X:X|*)] [prefix (*|A.B.C.D/M|X:X::X:X/M)])¶: Delete mac forwarding information. Any or all of these parameters may be wildcarded to (potentially) match more than one registration. The default value for the prefix parameter is the wildcard value *.

clear vnc nve (*|((vn|un) (A.B.C.D|X:X::X:X) [(un|vn) (A.B.C.D|X:X::X:X)]))¶: Delete prefixes associated with the NVE specified by the given VN and UN addresses. It is permissible to specify only one of VN or UN, in which case any matching registration will be deleted. It is also permissible to specify * in lieu of any VN or UN address, in which case all registrations will match.

Other VNC-Related Commands¶

Note: VNC-Related configuration can be obtained via the show running-configuration command when in enable mode.

The following commands are used to clear and display Virtual Network Control related information:

clear vnc counters¶: Reset the counter values stored by the NVA. Counter values can be seen using the show vnc commands listed above. This command is only available in enable mode.

show vnc summary¶: Print counter values and other general information about the NVA. Counter values can be reset using the clear vnc counters command listed below.

show vnc nves¶

show vnc nves vn|un ADDRESS¶: Display the NVA’s current clients. Specifying address limits the output to the NVEs whose addresses match address. The time since the NVA last communicated with the NVE, per-NVE summary counters and each NVE’s addresses will be displayed.

show vnc queries¶

show vnc queries PREFIX¶

Display active Query information. Queries remain valid for the default Response Lifetime (VNC Defaults Configuration) or NVE-group Response Lifetime (VNC NVE Group Configuration). Specifying prefix limits the output to Query Targets that fall within prefix.

Query information is provided for each querying NVE, and includes the Query Target and the time remaining before the information is removed.

show vnc registrations [all|local|remote|holddown|imported]¶

show vnc registrations [all|local|remote|holddown|imported] PREFIX¶

Display local, remote, holddown, and/or imported registration information. Local registrations are routes received via RFP, which are present in the NVA Registrations Cache. Remote registrations are routes received via BGP (VPN SAFIs), which are present in the NVE-group import tables. Holddown registrations are local and remote routes that have been withdrawn but whose holddown timeouts have not yet elapsed. Imported information represents routes that are imported into NVA and are made available to querying NVEs. Depending on configuration, imported routes may also be advertised via BGP. Specifying prefix limits the output to the registered prefixes that fall within prefix.

Registration information includes the registered prefix, the registering NVE addresses, the registered administrative cost, the registration lifetime and the time since the information was registered or, in the case of Holddown registrations, the amount of time remaining before the information is removed.

show vnc responses [active|removed]¶

show vnc responses [active|removed] PREFIX¶

Display all, active and/or removed response information which are present in the NVA Responses Cache. Responses remain valid for the default Response Lifetime (VNC Defaults Configuration) or NVE-group Response Lifetime (VNC NVE Group Configuration.) When Removal Responses are enabled (General VNC Configuration), such responses are listed for the Response Lifetime. Specifying prefix limits the output to the addresses that fall within prefix.

Response information is provided for each querying NVE, and includes the response prefix, the prefix-associated registering NVE addresses, the administrative cost, the provided response lifetime and the time remaining before the information is to be removed or will become inactive.

show memory vnc¶: Print the number of memory items allocated by the NVA.

Example VNC and VNC-GW Configurations¶

Mesh NVA Configuration¶

This example includes three NVAs, nine NVEs, and two NVE groups. Note that while not shown, a single physical device may support multiple logical NVEs. A three-way full mesh with three NVEs per NVA. shows code NVA-1 (192.168.1.100), NVA 2 (192.168.1.101), and NVA 3 (192.168.1.102), which are connected in a full mesh. Each is a member of the autonomous system 64512. Each NVA provides VNC services to three NVE clients in the 172.16.0.0/16 virtual-network address range. The 172.16.0.0/16 address range is partitioned into two NVE groups, group1 (172.16.0.0/17) and group2 (172.16.128.0/17).

Each NVE belongs to either NVE group group1 or NVE group group2. The NVEs NVE 1, NVE 2, NVE 4, NVE 7, and NVE 8 are members of the NVE group group1. The NVEs NVE 3, NVE 5, NVE 6, and NVE 9 are members of the NVE group group2.

Each NVA advertises NVE underlay-network IP addresses using the Tunnel Encapsulation Attribute.

A three-way full mesh with three NVEs per NVA.

bgpd.conf for NVA 1 (192.168.1.100):

router bgp 64512

    bgp router-id 192.168.1.100

    neighbor 192.168.1.101  remote-as 64512
    neighbor 192.168.1.102  remote-as 64512

    address-family ipv4 vpn
        neighbor 192.168.1.101 activate
        neighbor 192.168.1.102 activate
    exit-address-family

    vnc defaults
        rd 64512:1
        response-lifetime 200
        rt both 1000:1 1000:2
    exit-vnc

    vnc nve-group group1
        prefix vn 172.16.0.0/17
        rt both 1000:1
    exit-vnc

    vnc nve-group group2
        prefix vn 172.16.128.0/17
        rt both 1000:2
    exit-vnc

exit

bgpd.conf for NVA 2 (192.168.1.101):

router bgp 64512

    bgp router-id 192.168.1.101

    neighbor 192.168.1.100  remote-as 64512
    neighbor 192.168.1.102  remote-as 64512

    address-family ipv4 vpn
        neighbor 192.168.1.100 activate
        neighbor 192.168.1.102 activate
    exit-address-family

    vnc nve-group group1
        prefix vn 172.16.0.0/17
        rd 64512:1
        response-lifetime 200
        rt both 1000:1 1000:2
    exit-vnc
exit

bgpd.conf for NVA 3 (192.168.1.102):

router bgp 64512

    bgp router-id 192.168.1.102

    neighbor 192.168.1.101  remote-as 64512
    neighbor 192.168.1.102  remote-as 64512

    address-family ipv4 vpn
        neighbor 192.168.1.100 activate
        neighbor 192.168.1.101 activate
    exit-address-family

    vnc defaults
        rd 64512:1
        response-lifetime 200
        rt both 1000:1 1000:2
    exit-vnc

    vnc nve-group group1
        prefix vn 172.16.128.0/17
    exit-vnc
exit

Mesh NVA and VNC-GW Configuration¶

This example includes two NVAs, each with two associated NVEs, and two VNC-GWs, each supporting two CE routers physically attached to the four NVEs. Note that this example is showing a more complex configuration where VNC-GW is separated from normal NVA functions; it is equally possible to simplify the configuration and combine NVA and VNC-GW functions in a single FRR instance.

Meshed NVEs and VNC-GWs

As shown in Meshed NVEs and VNC-GWs, NVAs and VNC-GWs are connected in a full iBGP mesh. The VNC-GWs each have two CEs configured as route-reflector clients. Each client provides BGP updates with unicast routes that the VNC-GW reflects to the other client. The VNC-GW also imports these unicast routes into VPN routes to be shared with the other VNC-GW and the two NVAs. This route importation is controlled with the vnc redistribute statements shown in the configuration. Similarly, registrations sent by NVEs via RFP to the NVAs are exported by the VNC-GWs to the route-reflector clients as unicast routes. RFP registrations exported this way have a next-hop address of the CE behind the connected (registering) NVE. Exporting VNC routes as IPv4 unicast is enabled with the vnc export command below.

The configuration for VNC-GW 1 is shown below.

router bgp 64512
 bgp router-id 192.168.1.101
 bgp cluster-id 1.2.3.4
 neighbor 192.168.1.102 remote-as 64512
 neighbor 192.168.1.103 remote-as 64512
 neighbor 192.168.1.104 remote-as 64512
 neighbor 172.16.1.2 remote-as 64512
 neighbor 172.16.2.2 remote-as 64512
 !
 address-family ipv4 unicast
  redistribute vnc-direct
  no neighbor 192.168.1.102 activate
  no neighbor 192.168.1.103 activate
  no neighbor 192.168.1.104 activate
  neighbor 172.16.1.2 route-reflector-client
  neighbor 172.16.2.2 route-reflector-client
 exit-address-family
 !
 address-family ipv4 vpn
   neighbor 192.168.1.102 activate
   neighbor 192.168.1.103 activate
   neighbor 192.168.1.104 activate
 exit-address-family
 vnc export bgp mode ce
 vnc redistribute mode resolve-nve
 vnc redistribute ipv4 bgp-direct
 exit

Note that in the VNC-GW configuration, the neighboring VNC-GW and NVAs each have a statement disabling the IPv4 unicast address family. IPv4 unicast is on by default and this prevents the other VNC-GW and NVAs from learning unicast routes advertised by the route-reflector clients.

Configuration for NVA 2:

router bgp 64512
 bgp router-id 192.168.1.104
 neighbor 192.168.1.101 remote-as 64512
 neighbor 192.168.1.102 remote-as 64512
 neighbor 192.168.1.103 remote-as 64512
 !
 address-family ipv4 unicast
  no neighbor 192.168.1.101 activate
  no neighbor 192.168.1.102 activate
  no neighbor 192.168.1.103 activate
 exit-address-family
 !
 address-family ipv4 vpn
   neighbor 192.168.1.101 activate
   neighbor 192.168.1.102 activate
   neighbor 192.168.1.103 activate
 exit-address-family
 !
 vnc defaults
  response-lifetime 3600
  exit-vnc
 vnc nve-group nve1
  prefix vn 172.16.1.1/32
  response-lifetime 3600
  rt both 1000:1 1000:2
  exit-vnc
 vnc nve-group nve2
  prefix vn 172.16.2.1/32
  response-lifetime 3600
  rt both 1000:1 1000:2
  exit-vnc
 exit

VNC with FRR Route Reflector Configuration¶

A route reflector eliminates the need for a fully meshed NVA network by acting as the hub between NVAs. Two NVAs and a BGP Route Reflector shows BGP route reflector BGP Route Reflector 1 (192.168.1.100) as a route reflector for NVAs NVA 2``(192.168.1.101) and ``NVA 3 (192.168.1.102).

Two NVAs and a BGP Route Reflector

NVA 2 and NVA 3 advertise NVE underlay-network IP addresses using the Tunnel Encapsulation Attribute. BGP Route Reflector 1 reflects'' advertisements from ``NVA 2 to NVA 3 and vice versa.

As in the example of Mesh NVA Configuration, there are two NVE groups. The 172.16.0.0/16 address range is partitioned into two NVE groups, group1 (172.16.0.0/17) and group2 (172.16.128.0/17). The NVE NVE 4, NVE 7, and NVE 8 are members of the NVE group group1. The NVEs NVE 5, NVE 6, and NVE 9 are members of the NVE group group2.

bgpd.conf for BGP Route Reflector 1 on 192.168.1.100:

router bgp 64512

    bgp router-id 192.168.1.100

    neighbor 192.168.1.101 remote-as 64512
    neighbor 192.168.1.101 port 7179
    neighbor 192.168.1.101 description iBGP-client-192-168-1-101

    neighbor 192.168.1.102 remote-as 64512
    neighbor 192.168.1.102 port 7179
    neighbor 192.168.1.102 description iBGP-client-192-168-1-102

    address-family ipv4 unicast
        neighbor 192.168.1.101 route-reflector-client
        neighbor 192.168.1.102 route-reflector-client
    exit-address-family

    address-family ipv4 vpn
        neighbor 192.168.1.101 activate
        neighbor 192.168.1.102 activate

        neighbor 192.168.1.101 route-reflector-client
        neighbor 192.168.1.102 route-reflector-client
    exit-address-family

exit

bgpd.conf for NVA 2 on 192.168.1.101:

router bgp 64512

    bgp router-id 192.168.1.101

    neighbor 192.168.1.100  remote-as 64512

    address-family ipv4 vpn
        neighbor 192.168.1.100 activate
    exit-address-family

    vnc nve-group group1
        prefix vn 172.16.0.0/17
        rd 64512:1
        response-lifetime 200
        rt both 1000:1 1000:2
    exit-vnc
exit

bgpd.conf for NVA 2 on 192.168.1.102:

router bgp 64512

    bgp router-id 192.168.1.102

    neighbor 192.168.1.100  remote-as 64512

    address-family ipv4 vpn
        neighbor 192.168.1.100 activate
    exit-address-family

    vnc defaults
        rd 64512:1
        response-lifetime 200
        rt both 1000:1 1000:2
    exit-vnc

    vnc nve-group group1
        prefix vn 172.16.128.0/17
    exit-vnc
exit

While not shown, an NVA can also be configured as a route reflector.

VNC with Commercial Route Reflector Configuration¶

This example is identical to VNC with FRR Route Reflector Configuration with the exception that the route reflector is a commercial router. Only the VNC-relevant configuration is provided.

Two NVAs with a commercial route reflector

bgpd.conf for BGP route reflector Commercial Router on 192.168.1.104::

version 8.5R1.13;
routing-options {
    rib inet.0 {
        static {
            route 172.16.0.0/16 next-hop 192.168.1.104;
        }
    }
    autonomous-system 64512;
    resolution {
        rib inet.3 {
            resolution-ribs inet.0;
        }
        rib bgp.l3vpn.0 {
            resolution-ribs inet.0;
        }
    }
}
protocols {
    bgp {
        advertise-inactive;
        family inet {
            labeled-unicast;
        }
       group 1 {
            type internal;
            advertise-inactive;
            advertise-peer-as;
            import h;
            family inet {
                unicast;
            }
            family inet-vpn {
                unicast;
            }
            cluster 192.168.1.104;
            neighbor 192.168.1.101;
            neighbor 192.168.1.102;
        }
    }
}
policy-options {
    policy-statement h {
        from protocol bgp;
        then {
            as-path-prepend 64512;
            accept;
        }
    }
}

bgpd.conf for NVA 2 on 192.168.1.101:

router bgp 64512

    bgp router-id 192.168.1.101

    neighbor 192.168.1.100  remote-as 64512

    address-family ipv4 vpn
        neighbor 192.168.1.100 activate
    exit-address-family

    vnc nve-group group1
        prefix vn 172.16.0.0/17
        rd 64512:1
        response-lifetime 200
        rt both 1000:1 1000:2
    exit-vnc
exit

bgpd.conf for NVA 3 on 192.168.1.102:

router bgp 64512

    bgp router-id 192.168.1.102

    neighbor 192.168.1.100  remote-as 64512

    address-family ipv4 vpn
        neighbor 192.168.1.100 activate
    exit-address-family

    vnc defaults
        rd 64512:1
        response-lifetime 200
        rt both 1000:1 1000:2
    exit-vnc

    vnc nve-group group1
        prefix vn 172.16.128.0/17
    exit-vnc
exit

VNC with Redundant Route Reflectors Configuration¶

This example combines the previous two (VNC with FRR Route Reflector Configuration and VNC with Commercial Route Reflector Configuration) into a redundant route reflector configuration. BGP route reflectors BGP Route Reflector 1 and Commercial Router are the route reflectors for NVAs NVA 2 and NVA 3. The two NVAs have connections to both route reflectors.

FRR-based NVA with redundant route reflectors

bgpd.conf for BPGD Route Reflector 1 on 192.168.1.100:

router bgp 64512

 bgp router-id 192.168.1.100
 bgp cluster-id 192.168.1.100

 neighbor 192.168.1.104 remote-as 64512

 neighbor 192.168.1.101 remote-as 64512
 neighbor 192.168.1.101 description iBGP-client-192-168-1-101
 neighbor 192.168.1.101 route-reflector-client

 neighbor 192.168.1.102 remote-as 64512
 neighbor 192.168.1.102 description iBGP-client-192-168-1-102
 neighbor 192.168.1.102 route-reflector-client

 address-family ipv4 vpn
  neighbor 192.168.1.101 activate
  neighbor 192.168.1.102 activate
  neighbor 192.168.1.104 activate

  neighbor 192.168.1.101 route-reflector-client
  neighbor 192.168.1.102 route-reflector-client
 exit-address-family
exit

bgpd.conf for NVA 2 on 192.168.1.101:

router bgp 64512

 bgp router-id 192.168.1.101

 neighbor 192.168.1.100  remote-as 64512
 neighbor 192.168.1.104  remote-as 64512

 address-family ipv4 vpn
  neighbor 192.168.1.100 activate
  neighbor 192.168.1.104 activate
 exit-address-family

 vnc nve-group group1
  prefix vn 172.16.0.0/17
  rd 64512:1
  response-lifetime 200
  rt both 1000:1 1000:2
 exit-vnc
exit

bgpd.conf for NVA 3 on 192.168.1.102:

router bgp 64512

 bgp router-id 192.168.1.102

 neighbor 192.168.1.100  remote-as 64512
 neighbor 192.168.1.104  remote-as 64512

 address-family ipv4 vpn
  neighbor 192.168.1.100 activate
  neighbor 192.168.1.104 activate
 exit-address-family

 vnc defaults
  rd 64512:1
  response-lifetime 200
  rt both 1000:1 1000:2
 exit-vnc

 vnc nve-group group1
  prefix vn 172.16.128.0/17
 exit-vnc
exit

bgpd.conf for the Commercial Router route reflector on 192.168.1.104::

routing-options {
    rib inet.0 {
        static {
            route 172.16.0.0/16 next-hop 192.168.1.104;
        }
    }
    autonomous-system 64512;
    resolution {
        rib inet.3 {
            resolution-ribs inet.0;
        }
        rib bgp.l3vpn.0 {
            resolution-ribs inet.0;
        }
    }
}
protocols {
    bgp {
        advertise-inactive;
        family inet {
            labeled-unicast;
        }
       group 1 {
            type internal;
            advertise-inactive;
            advertise-peer-as;
            import h;
            family inet {
                unicast;
            }
            family inet-vpn {
                unicast;
            }
            cluster 192.168.1.104;
            neighbor 192.168.1.101;
            neighbor 192.168.1.102;
        }

       group 2 {
            type internal;
            advertise-inactive;
            advertise-peer-as;
            import h;
            family inet {
                unicast;
            }
            family inet-vpn {
                unicast;
            }
            neighbor 192.168.1.100;
        }

    }
}
policy-options {
    policy-statement h {
        from protocol bgp;
        then {
            as-path-prepend 64512;
            accept;
        }
    }
}

[1]	The nve-id is carried in the route distinguisher. It is the second octet of the eight-octet route distinguisher generated for Ethernet / L2 advertisements. The first octet is a constant 0xFF, and the third through eighth octets are set to the L2 ethernet address being advertised.

VRRP¶

VRRP stands for Virtual Router Redundancy Protocol. This protocol is used to allow multiple backup routers on the same segment to take over operation of each others’ IP addresses if the primary router fails. This is typically used to provide fault-tolerant gateways to hosts on the segment.

FRR implements VRRPv2 (RFC 3768) and VRRPv3 (RFC 5798). For VRRPv2, no authentication methods are supported; these are deprecated in the VRRPv2 specification as they do not provide any additional security over the base protocol.

Note

VRRP is supported on Linux 5.1+
VRRP does not implement Accept_Mode

Starting VRRP¶

The configuration file for vrrpd is vrrpd.conf. The typical location of vrrpd.conf is /etc/frr/vrrpd.conf.

If using integrated config, then vrrpd.conf need not be present and frr.conf is read instead.

VRRP supports all the common FRR daemon start options which are documented elsewhere.

Protocol Overview¶

From RFC 5798:

VRRP specifies an election protocol that dynamically assigns responsibility for a virtual router to one of the VRRP routers on a LAN. The VRRP router controlling the IPv4 or IPv6 address(es) associated with a virtual router is called the Master, and it forwards packets sent to these IPv4 or IPv6 addresses. VRRP Master routers are configured with virtual IPv4 or IPv6 addresses, and VRRP Backup routers infer the address family of the virtual addresses being carried based on the transport protocol. Within a VRRP router, the virtual routers in each of the IPv4 and IPv6 address families are a domain unto themselves and do not overlap. The election process provides dynamic failover in the forwarding responsibility should the Master become unavailable. For IPv4, the advantage gained from using VRRP is a higher-availability default path without requiring configuration of dynamic routing or router discovery protocols on every end-host. For IPv6, the advantage gained from using VRRP for IPv6 is a quicker switchover to Backup routers than can be obtained with standard IPv6 Neighbor Discovery mechanisms.

VRRP accomplishes these goals primarily by using a virtual MAC address shared between the physical routers participating in a VRRP virtual router. This reduces churn in the neighbor tables of hosts and downstream switches and makes router failover theoretically transparent to these devices.

FRR implements the election protocol and handles changing the operating system interface configuration in response to protocol state changes.

As a consequence of the shared virtual MAC requirement, VRRP is currently supported only on Linux, as Linux is the only operating system that provides the necessary features in its network stack to make implementing this protocol feasible.

When a VRRP router is acting as the Master router, FRR allows the interface(s) with the backed-up IP addresses to remain up and functional. When the router transitions to Backup state, these interfaces are set into protodown mode. This is an interface mode that is functionally equivalent to NO-CARRIER. Physical drivers typically use this state indication to drop traffic on an interface. In the case of VRRP, the interfaces in question are macvlan devices, which are virtual interfaces. Since the IP addresses managed by VRRP are on these interfaces, this has the same effect as removing these addresses from the interface, but is implemented as a state flag.

Configuring VRRP¶

VRRP is configured on a per-interface basis, with some global defaults accessible outside the interface context.

System Configuration¶

FRR’s VRRP implementation uses Linux macvlan devices to to implement the shared virtual MAC feature of the protocol. Currently, it does not create those system interfaces - they must be configured outside of FRR before VRRP can be enabled on them.

Each interface on which VRRP will be enabled must have at least one macvlan device configured with the virtual MAC and placed in the proper operation mode. The addresses backed up by VRRP are assigned to these interfaces.

Suppose you have an interface eth0 with the following configuration:

$ ip addr show eth0
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 02:17:45:00:aa:aa brd ff:ff:ff:ff:ff:ff
    inet 10.0.2.15/24 brd 10.0.2.255 scope global dynamic eth0
       valid_lft 72532sec preferred_lft 72532sec
    inet6 fe80::17:45ff:fe00:aaaa/64 scope link
       valid_lft forever preferred_lft forever

Suppose that the IPv4 and IPv6 addresses you want to back up are 10.0.2.16 and 2001:db8::370:7334, and that they will be managed by the virtual router with id 5. A macvlan device with the appropriate MAC address must be created before VRRP can begin to operate.

If you are using ifupdown2, the configuration is as follows:

iface eth0
 ...
 vrrp 5 10.0.2.16/24 2001:0db8::0370:7334/64

Applying this configuration with ifreload -a will create the appropriate macvlan device. If you are using iproute2, the equivalent configuration is:

ip link add vrrp4-2-1 link eth0 addrgenmode random type macvlan mode bridge
ip link set dev vrrp4-2-1 address 00:00:5e:00:01:05
ip addr add 10.0.2.16/24 dev vrrp4-2-1
ip link set dev vrrp4-2-1 up

ip link add vrrp6-2-1 link eth0 addrgenmode random type macvlan mode bridge
ip link set dev vrrp4-2-1 address 00:00:5e:00:02:05
ip addr add 2001:db8::370:7334/64 dev vrrp6-2-1
ip link set dev vrrp6-2-1 up

In either case, the created interfaces will look like this:

$ ip addr show vrrp4-2-1
5: vrrp4-2-1@eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
    link/ether 00:00:5e:00:01:05 brd ff:ff:ff:ff:ff:ff
    inet 10.0.2.16/24 scope global vrrp4-2-1
       valid_lft forever preferred_lft forever
    inet6 fe80::dc56:d11a:e69d:ea72/64 scope link stable-privacy
       valid_lft forever preferred_lft forever

$ ip addr show vrrp6-2-1
8: vrrp6-2-1@eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
 link/ether 00:00:5e:00:02:05 brd ff:ff:ff:ff:ff:ff
 inet6 2001:db8::370:7334/64 scope global
    valid_lft forever preferred_lft forever
 inet6 fe80::f8b7:c9dd:a1e8:9844/64 scope link stable-privacy
    valid_lft forever preferred_lft forever

Using vrrp4-2-1 as an example, a few things to note about this interface:

It is slaved to eth0; any packets transmitted on this interface will egress via eth0
Its MAC address is set to the VRRP IPv4 virtual MAC specified by the RFC for VRID 5
The VIP address 10.0.2.16 must not be present on the parent interface eth0.
The link local address on the interface is not derived from the interface MAC

First to note is that packets transmitted on this interface will egress via eth0, but with their Ethernet source MAC set to the VRRP virtual MAC. This is how FRR’s VRRP implementation accomplishes the virtual MAC requirement on real hardware.

Ingress traffic is a more complicated matter. Macvlan devices have multiple operating modes that change how ingress traffic is handled. Of relevance to FRR’s implementation are the bridge and private modes. In private mode, any ingress traffic on eth0 (in our example) with a source MAC address equal to the MAC address on any of eth0’s macvlan devices will be placed only on that macvlan device. This curious behavior is undesirable, since FRR’s implementation of VRRP needs to be able to receive advertisements from neighbors while in Backup mode - i.e., while its macvlan devices are in protodown on. If the macvlan devices are instead set to bridge mode, all ingress traffic shows up on all interfaces - including eth0 - regardless of source MAC or any other factor. Consequently, macvlans used by FRR for VRRP must be set to bridge mode or the protocol will not function correctly.

As for the MAC address assigned to this interface, the last byte of the address holds the VRID, in this case 0x05. The second to last byte is 0x01, as specified by the RFC for IPv4 operation. The IPv6 MAC address is be identical except that the second to last byte is defined to be 0x02. Two things to note from this arrangement:

There can only be up to 255 unique Virtual Routers on an interface (only 1 byte is available for the VRID)
IPv4 and IPv6 addresses must be assigned to different macvlan devices, because they have different MAC addresses

Finally, take note of the generated IPv6 link local address on the interface. For interfaces on which VRRP will operate in IPv6 mode, this link local cannot be derived using the usual EUI-64 method. This is because VRRP advertisements are sent from the link local address of this interface, and VRRP uses the source address of received advertisements as part of its election algorithm. If the IPv6 link local of a router is equivalent to the IPv6 link local in a received advertisement, this can cause both routers to assume the Master role (very bad). ifupdown knows to set the addrgenmode of the interface properly, but when using iproute2 to create the macvlan devices, you must be careful to manually specify addrgenmode random.

A brief note on the Backup state¶

It is worth noting here that an alternate choice for the implementation of the Backup state, such as removing all the IP addresses assigned to the macvlan device or deleting their local routes instead of setting the device into protodown on, would allow the protocol to function regardless of whether the macvlan device(s) are set to private or bridge mode. Indeed, the strange behavior of the kernel macvlan driver in private mode, whereby it performs what may be thought of as a sort of interface-level layer 2 “NAT” based on source MAC, can be traced back to a patch clearly designed to accommodate a VRRP implementation from a different vendor. However, the protodown based implementation allows for a configuration model in which FRR does not dynamically manage the addresses assigned on a system, but instead just manages interface state. Such a scenario was in mind when this protocol implementation was initially built, which is why the other choices are not currently present. Since support for placing macvlan devices into protodown was not added to Linux until version 5.1, this also explains the relatively restrictive kernel versioning requirement.

In the future other methods of implementing Backup state may be added along with a configuration knob to choose between them.

Interface Configuration¶

Continuing with the example from the previous section, we assume the macvlan interfaces have been properly configured with the proper MAC addresses and the IPvX addresses assigned.

In FRR, a possible VRRPv3 configuration for this interface is:

interface eth0
 vrrp 5 version 3
 vrrp 5 priority 200
 vrrp 5 advertisement-interval 1500
 vrrp 5 ip 10.0.2.16
 vrrp 5 ipv6 2001:0db8::0370:7334

VRRP will activate as soon as the first IPvX address configuration line is encountered. If you do not want this behavior, use the vrrp (1-255) shutdown command, and apply the no form when you are ready to activate VRRP.

At this point executing show vrrp will display the following:

ubuntu-bionic# show vrrp

 Virtual Router ID                    5
 Protocol Version                     3
 Autoconfigured                       Yes
 Shutdown                             No
 Interface                            eth0
 VRRP interface (v4)                  vrrp4-2-5
 VRRP interface (v6)                  vrrp6-2-5
 Primary IP (v4)                      10.0.2.15
 Primary IP (v6)                      fe80::9b91:7155:bf6a:d386
 Virtual MAC (v4)                     00:00:5e:00:01:05
 Virtual MAC (v6)                     00:00:5e:00:02:05
 Status (v4)                          Master
 Status (v6)                          Master
 Priority                             200
 Effective Priority (v4)              200
 Effective Priority (v6)              200
 Preempt Mode                         Yes
 Accept Mode                          Yes
 Advertisement Interval               1500 ms
 Master Advertisement Interval (v4)   1000 ms
 Master Advertisement Interval (v6)   1000 ms
 Advertisements Tx (v4)               14
 Advertisements Tx (v6)               14
 Advertisements Rx (v4)               0
 Advertisements Rx (v6)               0
 Gratuitous ARP Tx (v4)               1
 Neigh. Adverts Tx (v6)               1
 State transitions (v4)               2
 State transitions (v6)               2
 Skew Time (v4)                       210 ms
 Skew Time (v6)                       210 ms
 Master Down Interval (v4)            3210 ms
 Master Down Interval (v6)            3210 ms
 IPv4 Addresses                       1
 ..................................   10.0.2.16
 IPv6 Addresses                       1
 ..................................   2001:db8::370:7334

At this point, VRRP has sent gratuitous ARP requests for the IPv4 address, Unsolicited Neighbor Advertisements for the IPv6 address, and has asked Zebra to send Router Advertisements on its behalf. It is also transmitting VRRPv3 advertisements on the macvlan interfaces.

The Primary IP fields are of some interest, as the behavior may be counterintuitive. These fields show the source address used for VRRP advertisements. Although VRRPv3 advertisements are always transmitted on the macvlan interfaces, in the IPv4 case the source address is set to the primary IPv4 address on the base interface, eth0 in this case. This is a protocol requirement, and IPv4 VRRP will not function unless the base interface has an IPv4 address assigned. In the IPv6 case the link local of the macvlan interface is used.

If any misconfiguration errors are detected, VRRP for the misconfigured address family will not come up and the configuration issue will be logged to FRR’s configured logging destination.

Per the RFC, IPv4 and IPv6 virtual routers are independent of each other. For instance, it is possible for the IPv4 router to be in Backup state while the IPv6 router is in Master state; or for either to be completely inoperative while the other is operative, etc. Instances sharing the same base interface and VRID are shown together in the show output for conceptual convenience.

To complete your VRRP deployment, configure other routers on the segment with the exact same system and FRR configuration as shown above. Provided each router receives the others’ VRRP advertisements, the Master election protocol will run, one Master will be elected, and the other routers will place their macvlan interfaces into protodown on until Master fails or priority values are changed to favor another router.

Switching the protocol version to VRRPv2 is accomplished simply by changing version 3 to version 2 in the VRID configuration line. Note that VRRPv2 does not support IPv6, so any IPv6 configuration will be rejected by FRR when using VRRPv2.

Note

All VRRP routers initially start in Backup state, and wait for the calculated Master Down Interval to pass before they assume Master status. This prevents downstream neighbor table churn if another router is already Master with higher priority, meaning this box will ultimately assume Backup status once the first advertisement is received. However, if the calculated Master Down Interval is high and this router is configured such that it will ultimately assume Master status, then it will take a while for this to happen. This is a known issue.

All interface configuration commands are documented below.

[no] vrrp (1-255) [version (2-3)]¶: Create a VRRP router with the specified VRID on the interface. Optionally specify the protocol version. If the protocol version is not specified, the default is VRRPv3.

[no] vrrp (1-255) advertisement-interval (10-40950)¶: Set the advertisement interval. This is the interval at which VRRP advertisements will be sent. Values are given in milliseconds, but must be multiples of 10, as VRRP itself uses centiseconds.

[no] vrrp (1-255) ip A.B.C.D¶: Add an IPv4 address to the router. This address must already be configured on the appropriate macvlan device. Adding an IP address to the router will implicitly activate the router; see [no] vrrp (1-255) shutdown to override this behavior.

[no] vrrp (1-255) ipv6 X:X::X:X¶

Add an IPv6 address to the router. This address must already be configured on the appropriate macvlan device. Adding an IP address to the router will implicitly activate the router; see [no] vrrp (1-255) shutdown to override this behavior.

This command will fail if the protocol version is set to VRRPv2, as VRRPv2 does not support IPv6.

[no] vrrp (1-255) preempt¶: Toggle preempt mode. When enabled, preemption allows Backup routers with higher priority to take over Master status from the existing Master. Enabled by default.

[no] vrrp (1-255) priority (1-254)¶: Set the router priority. The router with the highest priority is elected as the Master. If all routers in the VRRP virtual router are configured with the same priority, the router with the highest primary IP address is elected as the Master. Priority value 255 is reserved for the acting Master router.

[no] vrrp (1-255) shutdown¶: Place the router into administrative shutdown. VRRP will not activate for this router until this command is removed with the no form.

Global Configuration¶

Show commands, global defaults and debugging configuration commands.

show vrrp [interface INTERFACE] [(1-255)] [json]¶: Shows VRRP status for some or all configured VRRP routers. Specifying an interface will only show routers configured on that interface. Specifying a VRID will only show routers with that VRID. Specifying json will dump each router state in a JSON array.

[no] debug vrrp [{protocol|autoconfigure|packets|sockets|ndisc|arp|zebra}]¶

Toggle debugging logs for VRRP components. If no component is specified, debugging for all components are turned on/off.

protocol: Logs state changes, election protocol decisions, and interface status changes.
autoconfigure: Logs actions taken by the autoconfiguration procedures. See Autoconfiguration.
packets: Logs details of ingress and egress packets. Includes packet decodes and hex dumps.
sockets: Logs details of socket configuration and initialization.
ndisc: Logs actions taken by the Neighbor Discovery component of VRRP.
arp: Logs actions taken by the ARP component of VRRP.
zebra: Logs communications with Zebra.

[no] vrrp default <advertisement-interval (1-4096)|preempt|priority (1-254)|shutdown>¶: Configure defaults for new VRRP routers. These values will not affect already configured VRRP routers, but will be applied to newly configured ones.

Autoconfiguration¶

In light of the complicated configuration required on the base system before VRRP can be enabled, FRR has the ability to automatically configure VRRP sessions by inspecting the interfaces present on the system. Since it is quite unlikely that macvlan devices with VRRP virtual MACs will exist on systems not using VRRP, this can be a convenient shortcut to automatically generate FRR configuration.

After configuring the interfaces as described in System Configuration, and configuring any defaults you may want, execute the following command:

[no] vrrp autoconfigure [version (2-3)]¶: Generates VRRP configuration based on the interface configuration on the base system. If the protocol version is not specified, the default is VRRPv3. Any existing interfaces that are configured properly for VRRP - i.e. have the correct MAC address, link local address (when required), IPv4 and IPv6 addresses - are used to create a VRRP router on their parent interfaces, with VRRP IPvX addresses taken from the addresses assigned to the macvlan devices. The generated configuration appears in the output of show run, which can then be modified as needed and written to the config file. The version parameter controls the protocol version; if using VRRPv2, keep in mind that IPv6 is not supported and will not be configured.

The following configuration is then generated for you:

interface eth0
 vrrp 5
 vrrp 5 ip 10.0.2.16
 vrrp 5 ipv6 2001:db8::370:7334

VRRP is automatically activated. Global defaults, if set, are applied.

You can then edit this configuration with vtysh as needed, and commit it by writing to the configuration file.

BMP¶

BMP (BGP Monitoring Protocol, RFC 7854) is used to send monitoring data from BGP routers to network management entities.

Implementation characteristics¶

The BMP implementation in FRR has the following properties:

only the RFC 7854 features are currently implemented. This means protocol version 3 without any extensions. It is not possible to use an older draft protocol version of BMP.
the following statistics codes are implemented:
- 0: count of prefixes rejected
- 2: count of duplicate prefix withdrawals
- 3: count of prefixes with loop in cluster id
- 4: count of prefixes with loop in AS-path
- 5: count of prefixes with loop in originator
- 11: count of updates subjected to RFC 7607 “treat as withdrawal” handling due to errors
- 65531: experimental count of prefixes rejected due to invalid next-hop
Note that stat items 3, 4 and 5 are specified to count updates, but FRR implements them as prefix-based counters.
route mirroring is fully implemented, however BGP OPEN messages are not currently included in route mirroring messages. Their contents can be extracted from the “peer up” notification for sessions that established successfully. OPEN messages for failed sessions cannot currently be mirrored.
route monitoring is available for IPv4 and IPv6 AFIs, unicast and multicast SAFIs. Other SAFIs (VPN, Labeled-Unicast, Flowspec, etc.) are not currently supported.
monitoring peers that have BGP add-path enabled on the session will result in somewhat unpredictable behaviour. Currently, the outcome is:
- route mirroring functions as intended, messages are copied verbatim
- the add-path ID is never included in route monitoring messages
- if multiple paths were received from a peer, an unpredictable path is picked and sent on the BMP session. The selection will differ for pre-policy and post-policy monitoring sessions.
- as long as any path is present, something will be advertised on BMP sessions. Only after the last path is gone a withdrawal will be sent on BMP sessions.
- updates to additional paths will trigger BMP route monitoring messages. There is no guarantee on consistency regarding which path is sent in these messages.
monitoring peers with RFC 5549 extended next-hops has not been tested.

Starting BMP¶

BMP is implemented as a loadable module. This means that to use BMP, bgpd must be started with the -M bmp option. It is not possible to enable BMP if bgpd was started without this option.

Configuring BMP¶

All of FRR’s BMP configuration options are located inside the router bgp ASN block. Configure BGP first before proceeding to BMP setup.

There is one option that applies to the BGP instance as a whole:

[no] bmp mirror buffer-limit(0-4294967294)¶

This sets the maximum amount of memory used for buffering BGP messages (updates, keepalives, …) for sending in BMP Route Mirroring.

The buffer is for the entire BGP instance; if multiple BMP targets are configured they reference the same buffer and do not consume additional memory. Queue overhead is included in accounting this memory, so the actual space available for BGP messages is slightly less than the value configured here.

If the buffer fills up, the oldest messages are removed from the buffer and any BMP sessions where the now-removed messages were still pending have their entire queue flushed and a “Mirroring Messages Lost” BMP message is sent.

BMP Route Monitoring is not affected by this option.

All other configuration is managed per targets:

[no] bmp targets NAME¶

Create/delete a targets group. As implied by the plural name, targets may cover multiple outbound active BMP sessions as well as inbound passive listeners.

If BMP sessions have the same configuration, putting them in the same bmp targets will reduce overhead.

BMP session configuration¶

Inside a bmp targets block, the following commands control session establishment:

[no] bmp connect HOSTNAME port (1-65535) {min-retry MSEC|max-retry MSEC}¶: Add/remove an active outbound BMP session. HOSTNAME is resolved via DNS, if multiple addresses are returned they are tried in nondeterministic order. Only one connection will be established even if multiple addresses are returned. min-retry and max-retry specify (in milliseconds) bounds for exponential backoff.

Warning

ip access-list and ipv6 access-list are checked for outbound connections resulting from bmp connect statements.

[no] bmp listener <X:X::X:X|A.B.C.D> port (1-65535)¶: Accept incoming BMP sessions on the specified address and port. You can use 0.0.0.0 and :: to listen on all IPv4/IPv6 addresses.

[no] ip access-list NAME¶

[no] ipv6 access-list NAME¶: Restrict BMP sessions to the addresses allowed by the respective access lists. The access lists are checked for both passive and active BMP sessions. Changes do not affect currently established sessions.

BMP data feed configuration¶

The following commands configure what BMP messages are sent on sessions associated with a particular bmp targets:

[no] bmp stats [interval (100-86400000)]¶: Send BMP Statistics (counter) messages at the specified interval (in milliseconds.)

[no] bmp monitor AFI SAFI <pre-policy|post-policy>¶

Perform Route Monitoring for the specified AFI and SAFI. Only IPv4 and IPv6 are currently valid for AFI, and only unicast and multicast are valid for SAFI. Other AFI/SAFI combinations may be added in the future.

All BGP neighbors are included in Route Monitoring. Options to select a subset of BGP sessions may be added in the future.

[no] bmp mirror¶

Perform Route Mirroring for all BGP neighbors. Since this provides a direct feed of BGP messages, there are no AFI/SAFI options to be configured.

All BGP neighbors are included in Route Mirroring. Options to select a subset of BGP sessions may be added in the future.

WATCHFRR¶

WATCHFRR is a daemon that handles failed daemon processes and intelligently restarts them as needed.

Starting WATCHFRR¶

WATCHFRR is started as per normal systemd startup and typically does not require end users management.

WATCHFRR commands¶

show watchfrr¶: Give status information about the state of the different daemons being watched by WATCHFRR

[no] watchfrr ignore DAEMON¶: Tell WATCHFRR to ignore a particular DAEMON if it goes unresponsive. This is particularly useful when you are a developer and need to debug a working system, without watchfrr pulling the rug out from under you.

Appendix¶

Reporting Bugs¶

This file describes the procedure for reporting FRRouting bugs. You are asked to follow this format when submitting bug reports.

Bugs submitted with woefully incomplete information will receive little attention and are likely to be closed. If you hit a suspected bug in an older version, you may be asked to test with a later version in your environment.

Often you may be asked for additional information to help solve the bug. Bugs may be closed after 30 days of non-response to requests to reconfirm or supply additional information.

Please report bugs on the project GitHub issue tracker at https://github.com/frrouting/frr/issues

Report Format & Requested Information¶

When reporting a bug, please provide the following information.

Your FRR version if it is a release build, or the commit hash if you built from source.
If you compiled from source, please provide your ./configure line, including all option flags.
A full list of the FRR daemons you run.
Your platform name and version, e.g. Ubuntu 18.04.
Problem description.
- Provide as much information as possible.
- Copy and paste relevant commands and their output to describe your network setup.
- Topology diagrams are helpful when reporting bugs involving more than one box.
- Platform routing tables and interface configurations are useful if you are reporting a routing issue.
Please be sure to review the provided information and censor any sensitive material.
All FRR configuration files you use. Again, please be sure to censor any sensitive information. For sensitive v4 / v6 addresses, we ask that you censor the inner octets; e.g., 192.XXX.XXX.32/24.
If you are reporting a crash and have a core file, please supply a stack trace using GDB:
```
$ gdb exec_file core_file
  (gdb) bt .
```
Run all FRR daemons with full debugging on and send only the portion of logs which are relevant to your problem.
Patches, workarounds, and fixes are always welcome.

See also

Basic Config Commands

Packet Binary Dump Format¶

FRR can dump routing protocol packets into a file with a binary format.

It seems to be better that we share the MRT’s header format for backward compatibility with MRT’s dump logs. We should also define the binary format excluding the header, because we must support both IP v4 and v6 addresses as socket addresses and / or routing entries.

In the last meeting, we discussed to have a version field in the header. But Masaki told us that we can define new ‘type’ value rather than having a ‘version’ field, and it seems to be better because we don’t need to change header format.

Here is the common header format. This is same as that of MRT.:

0                   1                   2                   3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                              Time                             |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|             Type              |            Subtype            |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                             Length                            |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

If ‘type’ is PROTOCOL_BGP4MP_ET, the common header format will contain an additional microsecond field (RFC6396 2011).:

0                   1                   2                   3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                              Time                             |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|             Type              |            Subtype            |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                             Length                            |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                          Microsecond                          |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

If ‘type’ is PROTOCOL_BGP4MP, ‘subtype’ is BGP4MP_STATE_CHANGE, and Address Family == IP (version 4):

0                   1                   2                   3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|        Source AS number       |     Destination AS number     |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|        Interface Index        |      Address Family           |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                        Source IP address                      |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                     Destination IP address                    |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|            Old State          |           New State           |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Where State is the value defined in RFC1771.

If ‘type’ is PROTOCOL_BGP4MP, ‘subtype’ is BGP4MP_STATE_CHANGE, and Address Family == IP version 6:

0                   1                   2                   3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|        Source AS number       |     Destination AS number     |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|        Interface Index        |      Address Family           |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                        Source IP address                      |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                        Source IP address (Cont'd)             |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                        Source IP address (Cont'd)             |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                        Source IP address (Cont'd)             |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                     Destination IP address                    |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                     Destination IP address (Cont'd)           |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                     Destination IP address (Cont'd)           |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                     Destination IP address (Cont'd)           |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|            Old State          |           New State           |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

If ‘type’ is PROTOCOL_BGP4MP, ‘subtype’ is BGP4MP_MESSAGE, and Address Family == IP (version 4):

0                   1                   2                   3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|        Source AS number       |     Destination AS number     |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|        Interface Index        |      Address Family           |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                        Source IP address                      |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                     Destination IP address                    |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                       BGP Message Packet                      |
|                                                               |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Where BGP Message Packet is the whole contents of the BGP4 message including header portion.

If ‘type’ is PROTOCOL_BGP4MP, ‘subtype’ is BGP4MP_MESSAGE, and Address Family == IP version 6:

0                   1                   2                   3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|        Source AS number       |     Destination AS number     |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|        Interface Index        |      Address Family           |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                        Source IP address                      |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                        Source IP address (Cont'd)             |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                        Source IP address (Cont'd)             |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                        Source IP address (Cont'd)             |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                     Destination IP address                    |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                     Destination IP address (Cont'd)           |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                     Destination IP address (Cont'd)           |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                     Destination IP address (Cont'd)           |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                       BGP Message Packet                      |
|                                                               |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

If ‘type’ is PROTOCOL_BGP4MP, ‘subtype’ is BGP4MP_ENTRY, and Address Family == IP (version 4):

0                   1                   2                   3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|            View #             |            Status             |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                        Time Last Change                       |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|       Address Family          |    SAFI       | Next-Hop-Len  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                        Next Hop Address                       |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Prefix Length |             Address Prefix [variable]         |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|       Attribute Length        |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|      BGP Attribute [variable length]                      |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

If ‘type’ is PROTOCOL_BGP4MP, ‘subtype’ is BGP4MP_ENTRY, and Address Family == IP version 6:

0                   1                   2                   3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|            View #             |            Status             |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                        Time Last Change                       |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|       Address Family          |    SAFI       | Next-Hop-Len  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                        Next Hop Address                       |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                        Next Hop Address (Cont'd)              |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                        Next Hop Address (Cont'd)              |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                        Next Hop Address (Cont'd)              |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Prefix Length |             Address Prefix [variable]         |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|     Address Prefix (cont'd) [variable]        |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|       Attribute Length        |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|      BGP Attribute [variable length]                          |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

BGP4 Attribute must not contain MP_UNREACH_NLRI. If BGP Attribute has MP_REACH_NLRI field, it must has zero length NLRI, e.g., MP_REACH_NLRI has only Address Family, SAFI and next-hop values.

If ‘type’ is PROTOCOL_BGP4MP and ‘subtype’ is BGP4MP_SNAPSHOT:

0                   1                   2                   3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|           View #              |       File Name [variable]    |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

The file specified in “File Name” contains all routing entries, which are in the format of subtype == BGP4MP_ENTRY.

Constants:

  /\* type value \*/
  #define MSG_PROTOCOL_BGP4MP    16
  #define MSG_PROTOCOL_BGP4MP_ET 17
  /\* subtype value \*/
  #define BGP4MP_STATE_CHANGE 0
  #define BGP4MP_MESSAGE 1
  #define BGP4MP_ENTRY 2
  #define BGP4MP_SNAPSHOT 3

Glossary¶

distance-vector: A distance-vector routing protocol in data networks determines the best route for data packets based on distance. Distance-vector routing protocols measure the distance by the number of routers a packet has to pass. Some distance-vector protocols also take into account network latency and other factors that influence traffic on a given route. To determine the best route across a network, routers on which a distance-vector protocol is implemented exchange information with one another, usually routing tables plus hop counts for destination networks and possibly other traffic information. Distance-vector routing protocols also require that a router informs its neighbours of network topology changes periodically. [distance-vector-rp]
link-state: Link-state algorithms (also known as shortest path first algorithms) flood routing information to all nodes in the internetwork. Each router, however, sends only the portion of the routing table that describes the state of its own links. In link-state algorithms, each router builds a picture of the entire network in its routing tables. Distance vector algorithms (also known as Bellman-Ford algorithms) call for each router to send all or some portion of its routing table, but only to its neighbors. In essence, link-state algorithms send small updates everywhere, while distance vector algorithms send larger updates only to neighboring routers. Distance vector algorithms know only about their neighbors. [link-state-rp]
Bellman-Ford: The Bellman–Ford algorithm is an algorithm that computes shortest paths from a single source vertex to all of the other vertices in a weighted digraph. [bellman-ford]

[distance-vector-rp]

https://en.wikipedia.org/wiki/Distance-vector_routing_protocol

[link-state-rp]

https://en.wikipedia.org/wiki/Link-state_routing_protocol

[bellman-ford]

https://en.wikipedia.org/wiki/Bellman-Ford_algorithm

Copyright notice¶

Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies.

Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one.

Permission is granted to copy and distribute translations of this manual into another language, under the above conditions for modified versions, except that this permission notice may be stated in a translation approved by Kunihiro Ishiguro.

FRRouting User Guide¶

Introduction¶

Overview¶

How to get FRR¶

About FRR¶

System Architecture¶

Supported Platforms¶

Feature Matrix¶

Known Kernel Issues¶

Supported RFCs¶

BGP¶

OSPF¶

ISIS¶

RIP¶

PIM¶

BFD¶

MPLS¶

SNMP¶

Mailing Lists¶

Bug Reports¶

Installation¶

From Packages¶

From Snapcraft¶

From Source¶

Getting the Source¶

Configuration¶

Python dependency, documentation and tests¶

Least-Privilege Support¶

Linux Notes¶

Building¶

Basic Setup¶

Daemons Configuration File¶

Services¶

Systemd¶

Operations¶

Restarting¶

Reloading¶

Starting a new daemon¶

Basics¶

Basic Commands¶

Config Commands¶

Basic Config Commands¶

Sample Config File¶

Configuration versioning, profiles and upgrade behavior¶

Profiles¶

Upgrade practices for interactive configuration¶

Upgrade practices for autogenerated configuration¶

Terminal Mode Commands¶

Common Invocation Options¶

Loadable Module Support¶

The SNMP Module¶

The FPM Module¶

Virtual Terminal Interfaces¶

VTY Overview¶

VTY Modes¶

VTY View Mode¶

VTY Enable Mode¶

VTY Other Modes¶

VTY CLI Commands¶

CLI Movement Commands¶

CLI Editing Commands¶

CLI Advanced Commands¶

Pipe Actions¶

VTY shell¶

Pager usage¶

Permissions and setup requirements¶

PAM support (experimental)¶

Integrated configuration mode¶

Configuration saving, file ownership and permissions¶

Filtering¶

IP Access List¶

IP Prefix List¶

ip prefix-list description¶

ip prefix-list sequential number control¶

Showing ip prefix-list¶

Clear counter of ip prefix-list¶

Route Maps¶

Route Map Command¶

Route Map Match Command¶

Route Map Set Command¶