STATIC

STATIC is a daemon that handles the installation and deletion of static routes.

Starting STATIC

STATIC supports all the common FRR daemon start options (Common Invocation Options).

Configuration for the daemon should be saved in the FRR integrated configuration file located in /etc/frr/frr.conf, see Integrated Config File for more information on system configuration.

Prior versions of FRR supported reading and writing per-daemon config files; however, with the introduction of the centralized management daemon mgmtd this could no longer be supported.

In order to allow for an orderly transition from per-daemon config files to the integrated config file, FRR daemons will continue to try and read their specific per-daemon configuration file as before. Additionally the config can still be loaded directly using the -f or --config-file CLI options; however, these files will not be updated when the configuration is written (e.g., with the write mem command).

Warning

Per-daemon files will no longer be updated when the user issues a write memory command. Therefore these per-daemon config files should only be used as a mechanism for transitioning to the integrated config, and then removed.

Static Route Commands

Static routing is a very fundamental feature of routing technology. It defines a static prefix and gateway, with several possible forms.

ip route NETWORK GATEWAY [tag TAG] [DISTANCE] [metric METRIC] [weight WEIGHT] [table TABLENO] [nexthop-vrf VRFNAME] [vrf VRFNAME]
ip route NETWORK IFNAME [tag TAG] [DISTANCE] [metric METRIC] [weight WEIGHT] [table TABLENO] [nexthop-vrf VRFNAME] [vrf VRFNAME]
ip route NETWORK (Null0|blackhole|reject) [tag TAG] [DISTANCE] [metric METRIC] [table TABLENO] [nexthop-vrf VRFNAME] [vrf VRFNAME]
ipv6 route NETWORK [from SRCPREFIX] GATEWAY [tag TAG] [DISTANCE] [metric METRIC] [weight WEIGHT] [table TABLENO] [nexthop-vrf VRFNAME] [vrf VRFNAME]
ipv6 route NETWORK [from SRCPREFIX] IFNAME [tag TAG] [DISTANCE] [metric METRIC] [weight WEIGHT] [table TABLENO] [nexthop-vrf VRFNAME] [vrf VRFNAME]
ipv6 route NETWORK [from SRCPREFIX] (Null0|blackhole|reject) [tag TAG] [DISTANCE] [metric METRIC] [table TABLENO] [nexthop-vrf VRFNAME] [vrf VRFNAME]

NETWORK is destination prefix with a valid v4 or v6 network based upon initial form of the command.

GATEWAY is the IP address to use as next-hop for the prefix. Routes of type v4 can use v4 and v6 next-hops, v6 routes only support v6 next-hops.

IFNAME is the name of the interface to use as next-hop. If only IFNAME is specified (without GATEWAY), a connected route will be created. Note that some of the other keywords are not valid interface names: vrf, table, label, tag, color, segments, and nexthop-vrf.

When both IFNAME and GATEWAY are specified together, it binds the route to the specified interface. In this case, it is also possible to specify onlink to force the kernel to consider the next-hop as “on link” on the given interface.

Alternatively, the gateway can be specified as Null0 or blackhole to create a blackhole route that drops all traffic. It can also be specified as reject to create an unreachable route that rejects traffic with ICMP “Destination Unreachable” messages.

TAG is an optional 32-bit unsigned integer (1–4294967295) that marks the route entry in the RIB. See Route Tag for details and limitations.

DISTANCE is an optional administrative distance (1–255; default 1). See Administrative Distance and Metric for details.

METRIC is an optional route metric (0–4294967295; default 0). See Administrative Distance and Metric for details.

WEIGHT is an optional parameter that specifies the weight attributed to a nexthop when multiple nexthops are configured for the same static route. The value must be between 1 and 65535. The Linux kernel only supports 8-bit weights for multipath static routes, but Zebra creates and uses nexthop-groups for this, for which the kernel supports 16-bit weights since version 6.12.

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.

vrf VRFNAME allows you to create the route in a specified vrf.

nexthop-vrf VRFNAME allows you to create a leaked route with a nexthop in the specified VRFNAME. nexthop-vrf cannot be currently used with namespace based vrfs.

The IPv6 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 (also known as a multipath route), 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 multipath 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

A weight can be associated with each nexthop to influence traffic distribution across the paths. In this example, both nexthops are installed as a multipath route, with traffic distributed proportionally according to the configured weights:

ip route 10.0.0.0/8 10.0.0.2 weight 10
ip route 10.0.0.0/8 10.0.0.3 weight 100

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

Administrative Distance and Metric

Static routes are grouped internally by (table-id, distance, metric). Nexthops that share the same tuple belong to the same path group and are installed in the RIB together as an ECMP set. Nexthops in different path groups for the same prefix are independent: all path groups are present in the RIB, but only the group with the lowest distance (and, for the same distance, the lowest metric) is selected at any time.

ECMP — Multiple nexthops with the same (distance, metric) form an equal-cost multipath group and are active in the RIB together:

ip route 10.0.0.0/8 10.0.0.2
ip route 10.0.0.0/8 10.0.0.3

Both nexthops share (distance=1, metric=0) and are active in the RIB as ECMP.

Floating static routes — Nexthops with different (distance, metric) tuples form separate path groups. All groups are present in the RIB; the group with the best preference (lowest distance, then lowest metric) is selected. A lower-preference group is promoted when the higher-preference group becomes unreachable.

Floating by distance:

ip route 10.0.0.0/8 10.0.0.2
ip route 10.0.0.0/8 10.0.0.3 200

10.0.0.2 is the primary (distance 1); 10.0.0.3 is the fallback (distance 200), promoted only when 10.0.0.2 is gone.

Floating by metric (same distance, different metric):

ip route 10.0.0.0/8 10.0.0.2 metric 100
ip route 10.0.0.0/8 10.0.0.3 metric 200

10.0.0.2 is the primary (metric 100); 10.0.0.3 is the fallback (metric 200), promoted only when 10.0.0.2 is gone.

Nexthop uniqueness and automatic move — A given nexthop (identified by its forwarding information: type, gateway address, and interface) may appear in at most one path group under a prefix at a time. If a nexthop is reconfigured with a new distance or metric, FRR automatically removes it from the old path group and installs it in the new one:

ip route 10.0.0.0/8 10.0.0.2 10
! Reconfigure with a new distance — old entry is removed automatically:
ip route 10.0.0.0/8 10.0.0.2 20

After the second command there is exactly one path group for 10.0.0.2 at distance 20; no stale distance-10 entry remains. The same applies when metric is changed.

Removing routes — FRR identifies the nexthop to remove by its nexthop identity (gateway address, interface, or blackhole type) and ignores the distance and metric arguments. Because a given nexthop can appear in at most one path group for a prefix, the search is always unambiguous:

no ip route 10.0.0.0/8 10.0.0.2
no ip route 10.0.0.0/8 10.0.0.2 10
no ip route 10.0.0.0/8 10.0.0.2 10 metric 50

All three commands above remove the same nexthop 10.0.0.2, regardless of which distance or metric it was configured with.

Route Tag

TAG is a 32-bit unsigned integer (1–4294967295) that marks a route entry in the RIB. It can be matched by routing policy (route-maps, prefix-lists) to filter or modify routes based on their tag value.

The tag is a per-path-group attribute: it is shared by all nexthops in a path group and carried into the RIB. Unlike distance and metric, tag is not part of the path group identity — two nexthops with the same (distance, metric) always belong to the same path group regardless of their configured tags.

Per-path-group tag — Assigning a distinct tag to each path group lets routing policy distinguish primary from backup routes:

ip route 10.0.0.0/8 10.0.0.2 tag 100 10
ip route 10.0.0.0/8 10.0.0.3 tag 200 20

10.0.0.2 (distance 10) carries tag 100 and 10.0.0.3 (distance 20) carries tag 200. Both tags are visible in the RIB simultaneously.

Note

Same (distance, metric), different tag: because tag is not part of the path group key, two nexthops with the same (distance, metric) belong to the same path group and share a single tag in the RIB. When nexthops in the same path group are configured with different tags, the tag with the maximum value takes effect in the RIB. show running-config stores the operator-configured value for each nexthop individually (YANG per-nexthop state), while the RIB carries the maximum value tag for the whole group. When a nexthop is removed, the path tag is automatically recomputed as the maximum of the remaining configured tags:

ip route 10.0.0.0/8 10.0.0.2 tag 100 10
ip route 10.0.0.0/8 10.0.0.3 tag 200 10

Both nexthops are grouped at distance 10. The RIB tag is 200 (the maximum). show running-config shows 100 for 10.0.0.2 and 200 for 10.0.0.3. Removing 10.0.0.3 lowers the RIB tag to 100 (10.0.0.2’s configured tag). To assign independent tags visible separately in the RIB, use different distances or metrics.

SR-TE Route Commands

It is possible to specify a route using a SR-TE policy configured in Zebra.

e.g. to use the SR-TE policy with endpoint 6.6.6.6 and color 123 to reach the network 9.9.9.9/24:

ip route 9.9.9.9/24 6.6.6.6 color 123

SRv6 Route Commands

It is possible to specify a static route for ipv6 prefixes using an SRv6 segments instruction. The / separator can be used to specify multiple segments instructions.

ipv6 route X:X::X:X <X:X::X:X|nexthop> segments U:U::U:U/Y:Y::Y:Y/Z:Z::Z:Z

router(config)# ipv6 route 2005::1/64 sr0 segments 2001:db8:aaaa::7/2002::4/2002::3/2002::2

router# show ipv6 route
[..]
S>* 2005::/64 [1/0] is directly connected, sr0, seg6 2001:db8:aaaa::7,2002::4,2002::3,2002::2, weight 1, 00:00:06

STATIC also supports steering of IPv4 traffic over an SRv6 SID list, as shown in the example below.

ip route A.B.C.D <A.B.C.D|nexthop> segments U:U::U:U/Y:Y::Y:Y/Z:Z::Z:Z

router(config)# ip route 10.0.0.0/24 sr0 segments fcbb:bbbb:1:2:3:fe00::

router# show ip route
[..]
S>* 10.0.0.0/24 [1/0] is directly connected, sr0, seg6 fcbb:bbbb:1:2:3:fe00::, weight 1, 00:00:06

Optionally, the user can specify the SRv6 Headend Behavior to be used for encapsulation. Currently, STATIC supports the following behaviors:

  • H.Encaps

  • H.Encaps.Red

When the behavior is not specified, STATIC defaults to using H.Encaps.

ipv6 route X:X::X:X <X:X::X:X|nexthop> segments U:U::U:U/Y:Y::Y:Y/Z:Z::Z:Z [encap-behavior <H_Encaps|H_Encaps_Red>]
ip route A.B.C.D <A.B.C.D|nexthop> segments U:U::U:U/Y:Y::Y:Y/Z:Z::Z:Z [encap-behavior <H_Encaps|H_Encaps_Red>]
router(config)# ipv6 route 2001:db8:1:1::1/128 sr0 segments fcbb:bbbb:1:2:3:fe00:: encap-behavior H_Encaps
router(config)# ipv6 route 2001:db8:1:1::2/128 sr0 segments fcbb:bbbb:1:2:3:fe00:: encap-behavior H_Encaps_Red

router# show ipv6 route
[..]
S>* 2001:db8:1:1::1/128 [1/0] is directly connected, sr0, seg6 fcbb:bbbb:1:2:3:fe00::, weight 1, 00:00:06
S>* 2001:db8:1:1::2/128 [1/0] is directly connected, sr0, seg6 fcbb:bbbb:1:2:3:fe00::, encap behavior H.Encaps.Red, weight 1, 00:00:06

router(config)# ip route 10.0.0.1/32 sr0 segments fcbb:bbbb:1:2:3:fe00:: encap-behavior H_Encaps
router(config)# ip route 10.0.0.2/32 sr0 segments fcbb:bbbb:1:2:3:fe00:: encap-behavior H_Encaps_Red

router# show ip route
[..]
S>* 10.0.0.1/32 [1/0] is directly connected, sr0, seg6 fcbb:bbbb:1:2:3:fe00::, weight 1, 00:00:06
S>* 10.0.0.2/32 [1/0] is directly connected, sr0, seg6 fcbb:bbbb:1:2:3:fe00::, encap behavior H.Encaps.Red, weight 1, 00:00:06

SRv6 Static SIDs Commands

segment-routing

Move from configure mode to segment-routing node.

srv6

Move from segment-routing node to srv6 node.

static-sids

Move from srv6 node to static-sids node. In this static-sids node, user can configure static SRv6 SIDs.

sid X:X::X:X/M locator NAME behavior <uN|uA|uDT4|uDT6|uDT46> [vrf VRF] [interface IFNAME [nexthop X:X::X:X]]

Specify the locator sid manually. Configuring a local sid in a purely static mode by specifying the sid value would generate a unique SID. This feature will support the configuration of static SRv6 decapsulation on the system.

It supports the following behaviors: uN, uA, uDT4, uDT6, uDT46.

When configuring the local sid, if the action is set to ‘uN’, no vrf should be set. For uDT4, uDT6 and uDT46, it is necessary to specify a specific vrf. The uA behavior requires the outgoing interface and optionally the IPv6 address of the Layer 3 adjacency to which the packet should be forwarded.

router# configure terminal
router(config)# segment-routing
router(config-sr)# srv6
router(config-srv6)# static-sids
router(config-srv6-sids)# sid fcbb:bbbb:1:fe01::/64 locator LOC1 behavior uDT6 vrf Vrf1
router(config-srv6-sids)# sid fcbb:bbbb:1:fe02::/64 locator LOC1 behavior uDT4 vrf Vrf1
router(config-srv6-sids)# sid fcbb:bbbb:1:fe03::/64 locator LOC1 behavior uDT46 vrf Vrf2
router(config-srv6-sids)# sid fcbb:bbbb:1:fe04::/64 locator LOC1 behavior uA interface eth0 nexthop 2001::2

router(config-srv6-locator)# show run
...
segment-routing
 srv6
  static-sids
   sid    fcbb:bbbb:1:fe01::/64 locator LOC1 behavior uDT6 vrf Vrf1
   sid    fcbb:bbbb:1:fe02::/64 locator LOC1 behavior uDT4 vrf Vrf1
   sid    fcbb:bbbb:1:fe03::/64 locator LOC1 behavior uDT46 vrf Vrf2
   sid    fcbb:bbbb:1:fe04::/64 locator LOC1 behavior uA interface eth0 nexthop 2001::2
    !
...