This feature makes use of the Multi-Homed Prefix (MHP) model described in RFC 8518 to compute a backup IP next-hop using an alternate ABR or ASBR for external prefixes and to an alternate router owner for local anycast prefixes.
The feature applies to OSPF routes of external /32 prefixes (OSPFv2 routes types 3, 4, 5, and 7) and local /32 anycast prefixes if the prefix is not protected by base LFA.
The computed IP next-hop based backup path is programmed for SR-OSPF node SID tunnels of external /32 prefixes and to /32 prefixes in same area as the computing node and which are advertised by multiple routers (anycast prefixes) in both algorithm 0 and flexible-algorithm numbers.
The details of the configuration of this feature are provided in the 7450 ESS, 7750 SR, 7950 XRS, and VSR Unicast Routing Protocols Guide section Feature applicability.