The OSPFv2 Loop-Free Alternate Fast Reroute feature is not supported on routers that are virtual links headends.
The OSPFv2 Loop-Free Alternate Fast Reroute feature is supported only in global VPN routing and forwarding (VRF) OSPF instances.
You cannot configure a traffic engineering (TE) tunnel interface as a protected interface. Use the MPLS Traffic Engineering--Fast
Reroute Link and Node Protection feature to protect these tunnels. See the “MPLS Traffic Engineering--Fast Reroute Link and
Node Protection” section in the
Cisco IOS XE Multiprotocol Label Switching Configuration Guide for more information.
You can configure a TE tunnel interface in a repair path, but OSPF will not verify the tunnel’s placement; you must ensure
that it is not crossing the physical interface it is intended to protect.
Not all routes can have repair paths. Multipath primary routes might have repair paths for all, some, or no primary paths,
depending on network topology, the connectivity of the computing router, and the attributes required of repair paths.