PATH¶
PATH is a daemon that handles the installation and deletion of Segment Routing (SR) Policies.
Starting PATH¶
Default configuration file for pathd is pathd.conf
. The typical
location of pathd.conf
is /etc/frr/pathd.conf.
If the user is using integrated config, then pathd.conf
need not be
present and the frr.conf
is read instead.
PATH supports all the common FRR daemon start options which are documented elsewhere.
PCEP Support¶
To build the PCC for pathd, the externall library pceplib 1.2 is required.
To build FRR with support for PCEP the following steps must be followed:
- Checkout and build pceplib:
`
$ git clone https://github.com/volta-networks/pceplib
$ cd pceplib
$ make
$ make install
$ export PCEPLIB_ROOT=$PWD
`
- Configure FRR with the extra parameters:
`
--enable-pcep LDFLAGS="-L${PCEPLIB_ROOT}/install/lib" CPPFLAGS="-I${PCEPLIB_ROOT}/install/include"
`
To start pathd with pcep support the extra parameter -M pathd_pcep should be passed to the pathd daemon.
Pathd Configuration¶
Example:
debug pathd pcep basic
segment-routing
traffic-eng
segment-list SL1
index 10 mpls label 16010
index 20 mpls label 16030
!
policy color 1 endpoint 1.1.1.1
name default
binding-sid 4000
candidate-path preference 100 name CP1 explicit segment-list SL1
candidate-path preference 200 name CP2 dynamic
affinity include-any 0x000000FF
bandwidth 100000
metric bound msd 16 required
metric te 10
objective-function mcp required
!
pcep
pce-config GROUP1
source-address 1.1.1.1
tcp-md5-auth secret
timer keep-alive 30
!
pce PCE1
config GROUP1
address ip 10.10.10.10
!
pce PCE2
config GROUP1
address ip 9.9.9.9
!
pcc
peer PCE1 precedence 10
peer PCE2 precedence 20
!
!
!
!
Configuration Commands¶
-
segment-routing
¶ Configure segment routing.
-
traffic-eng
¶ Configure segment routing traffic engineering.
-
[no] segment-list NAME
¶ Delete or start a segment list definition.
-
[no] index INDEX mpls label LABEL [nai node ADDRESS]
¶ Delete or specify a segment in a segment list definition.
-
[no] policy color COLOR endpoint ENDPOINT
¶ Delete or start a policy definition.
-
name NAME
¶ Specify the policy name.
-
binding-sid LABEL
¶ Specify the policy SID.
-
[no] candidate-path preference PREFERENCE name NAME explicit segment-list SEGMENT-LIST-NAME
¶ Delete or define an explicit candidate path.
-
[no] candidate-path preference PREFERENCE name NAME dynamic
¶ Delete or start a dynamic candidate path definition.
-
[no] affinity {exclude-any|include-any|include-all} BITPATTERN
¶ Delete or specify an affinity constraint for a dynamic candidate path.
-
[no] bandwidth BANDWIDTH [required]
¶ Delete or specify a bandwidth constraint for a dynamic candidate path.
-
[no] metric [bound] METRIC VALUE [required]
¶ Delete or specify a metric constraint for a dynamic candidate path.
- The possible metrics are:
- igp: IGP metric
- te: TE metric
- hc: Hop Counts
- abc: Aggregate bandwidth consumption
- mll: Load of the most loaded link
- igp: Cumulative IGP cost
- cte: Cumulative TE cost
- igp: P2MP IGP metric
- pte: P2MP TE metric
- phc: P2MP hop count metric
- msd: Segment-ID (SID) Depth
- pd: Path Delay metric
- pdv: Path Delay Variation metric
- pl: Path Loss metric
- ppd: P2MP Path Delay metric
- pdv: P2MP Path Delay variation metric
- ppl: P2MP Path Loss metric
- nap: Number of adaptations on a path
- nlp: Number of layers on a path
- dc: Domain Count metric
- bnc: Border Node Count metric
-
[no] objective-function OBJFUN1 [required]
¶ Delete or specify a PCEP objective function constraint for a dynamic candidate path.
- The possible functions are:
- mcp: Minimum Cost Path [RFC5541]
- mlp: Minimum Load Path [RFC5541]
- mbp: Maximum residual Bandwidth Path [RFC5541]
- mbc: Minimize aggregate Bandwidth Consumption [RFC5541]
- mll: Minimize the Load of the most loaded Link [RFC5541]
- mcc: Minimize the Cumulative Cost of a set of paths [RFC5541]
- spt: Shortest Path Tree [RFC8306]
- mct: Minimum Cost Tree [RFC8306]
- mplp: Minimum Packet Loss Path [RFC8233]
- mup: Maximum Under-Utilized Path [RFC8233]
- mrup: Maximum Reserved Under-Utilized Path [RFC8233]
- mtd: Minimize the number of Transit Domains [RFC8685]
- mbn: Minimize the number of Border Nodes [RFC8685]
- mctd: Minimize the number of Common Transit Domains [RFC8685]
- msl: Minimize the number of Shared Links [RFC8800]
- mss: Minimize the number of Shared SRLGs [RFC8800]
- msn: Minimize the number of Shared Nodes [RFC8800]
-
[no] debug pathd pcep [basic|path|message|pceplib]
¶ Enable or disable debugging for the pcep module:
- basic: Enable basic PCEP logging
- path: Log the path structures
- message: Log the PCEP messages
- pceplib: Enable pceplib logging
-
pcep
¶ Configure PCEP support.
-
[no] pce-config NAME
¶ Define a shared PCE configuration that can be used in multiple PCE declarations.
-
[no] pce NAME
¶ Define or delete a PCE definition.
-
config WORD
¶ Select a shared configuration. If not defined, the default configuration will be used.
-
address <ip A.B.C.D | ipv6 X:X::X:X> [port (1024-65535)]
¶ Define the address and port of the PCE.
If not specified, the port is the standard PCEP port 4189.
This should be specified in the PCC peer definition.
-
source-address [ip A.B.C.D | ipv6 X:X::X:X] [port PORT]
¶ Define the address and/or port of the PCC as seen by the PCE. This can be used in a configuration group or a PCC peer declaration.
If not specified, the source address will be the router identifier selected by zebra, and the port will be the standard PCEP port 4189.
This can be specified in either the PCC peer definition or in a configuration group.
-
tcp-md5-auth WORD
¶ Enable TCP MD5 security with the given secret.
This can be specified in either the PCC peer definition or in a configuration group.
-
sr-draft07
¶ Specify if a PCE only support segment routing draft 7, this flag will limit the PCC behavior to this draft.
This can be specified in either the PCC peer definition or in a configuration group.
-
pce-initiated
¶ Specify if PCE-initiated LSP should be allowed for this PCE.
This can be specified in either the PCC peer definition or in a configuration group.
-
timer [keep-alive (1-63)] [min-peer-keep-alive (1-255)] [max-peer-keep-alive (1-255)] [dead-timer (4-255)] [min-peer-dead-timer (4-255)] [max-peer-dead-timer (4-255)] [pcep-request (1-120)] [session-timeout-interval (1-120)] [delegation-timeout (1-60)]
¶ Specify the PCEP timers.
This can be specified in either the PCC peer definition or in a configuration group.
-
[no] pcc
¶ Disable or start the definition of a PCC.
-
msd (1-32)
¶ Specify the maximum SID depth in a PCC definition.
-
[no] peer WORD [precedence (1-255)]
¶ Specify a peer and its precedence in a PCC definition.
Introspection Commands¶
-
show sr-te policy [detail]
¶ Display the segment routing policies.
router# show sr-te policy
Endpoint Color Name BSID Status
------------------------------------------
1.1.1.1 1 default 4000 Active
router# show sr-te policy detail
Endpoint: 1.1.1.1 Color: 1 Name: LOW_DELAY BSID: 4000 Status: Active
Preference: 100 Name: cand1 Type: explicit Segment-List: sl1 Protocol-Origin: Local
* Preference: 200 Name: cand1 Type: dynamic Segment-List: 32453452 Protocol-Origin: PCEP
The asterisk (*) marks the best, e.g. active, candidate path. Note that for segment-lists which are retrieved via PCEP a random number based name is generated.
-
show debugging pathd
¶ Display the current status of the pathd debugging.
-
show debugging pathd-pcep
¶ Display the current status of the pcep module debugging.
-
show sr-te pcep counters
¶ Display the counters from pceplib.
-
show sr-te pcep pce-config [NAME]
¶ Display a shared configuration. if no name is specified, the default configuration will be displayed.
-
show sr-te pcep pcc
¶ Display PCC information.
-
show sr-te pcep session [NAME]
¶ Display the information of a PCEP session, if not name is specified all the sessions will be displayed.
Usage with BGP route-maps¶
It is possible to steer traffic ‘into’ a segment routing policy for routes learned through BGP using route-maps:
route-map SET_SR_POLICY permit 10
set sr-te color 1
!
router bgp 1
bgp router-id 2.2.2.2
neighbor 1.1.1.1 remote-as 1
neighbor 1.1.1.1 update-source lo
!
address-family ipv4 unicast
neighbor 1.1.1.1 next-hop-self
neighbor 1.1.1.1 route-map SET_SR_POLICY in
redistribute static
exit-address-family
!
!
In this case, the SR Policy with color 1 and endpoint 1.1.1.1 is selected.