BIER uses basic LFA and cannot use TI-LFA or remote-LFA. The following commands configure the LFA under IGP. Currently, BIER FRR supports ISIS only.
*A:swsim100>config>router>isis# loopfree-alternates
- loopfree-alternates
- no loopfree-alternates
[no] augment-route-* - Enable/disable augmenting route table with LFA info
needed by LDP and other apps
exclude + Configure LFA exclude policies
[no] remote-lfa + Enable/disable remote loopfree-alternate
[no] ti-lfa + Enable/disable Topology Independent loopfree-alternate
*A:swsim100>config>router>ospf# loopfree-alternates
- loopfree-alternates
- no loopfree-alternates
[no] augment-route-* - Enable/disable augmenting route table with LFA info
needed by LDP and other apps
exclude + Configure LFA exclude policies
[no] multi-homed-pr* + Enable/disable multi-homed prefix loopfree-alternate
[no] remote-lfa + Enable/disable remote loopfree-alternate
[no] ti-lfa + Enable/disable Topology Independent loopfree-alternate
In the following output example, next-hop 10.20.1.4 is protected through 10.20.1.2 using a basic LFA.
*A:Dut-C# show router bier routing sub-domain 0
===============================================================================
Destination Prefix Bfr-ID Age
Neighbor
Nexthop
Interface
-------------------------------------------------------------------------------
===============================================================================
BIER Routing Database Sub-Domain 0 BSL 256
===============================================================================
10.20.1.1 1 0d 01:17:21
10.20.1.2 (Backup)
10.180.3.2
ip-10.180.3.3
10.20.1.4
10.180.11.4
ip-10.180.11.4
10.20.1.2 2 0d 01:17:21
10.20.1.2
10.180.3.2
ip-10.180.3.3
10.20.1.4 (Backup)
10.180.11.4
ip-10.180.11.4
10.20.1.4 0 0d 01:17:21
10.20.1.4
10.180.11.4
ip-10.180.11.3
===============================================================================
Total (Sub-Domain 0): 3
===============================================================================
Total BIER Routing entries : 3
===============================================================================
*A:Dut-C# show router bier forwarding sub-domain 0
===============================================================================
Neighbor
Nexthop
Interface
[SI]: Label
Forwarding Bit Mask
BFR-ID : Prefix
-------------------------------------------------------------------------------
The configure router bier fast-reroute command enables BIER FRR.
When FRR is enabled, link protection is enabled for all BIER neighbors that can find an underlay LFA. The neighbor BFR label is pushed first.