Configuring LFA using backup node SID in OSPF

LFA using a backup node SID is enabled by configuring a backup node SID at an ABR/ASBR that acts as a backup to the primary exit ABR/ASBR of inter-area/inter-as routes learned as BGP labeled routes.

config>router>ospf>segment-routing$
        — backup-node-sid ip-prefix/prefix-length index 0..4294967295
        — backup-node-sid ip-prefix/prefix-length label 1..4294967295

The user can enter either a label or an index for the backup node SID.

Note: This feature only allows the configuration of a single backup node SID per OSPF instance and per ABR/ASBR. In other words, only a pair of ABR/ASBR nodes can back up each other in a an OSPF domain. Each time the user invokes the above command within the same OSPF instance, it overrides any previous configuration of the backup node SID. The same ABR/ASBR can, however, participate in multiple OSPF instances and provide a backup support within each instance.