The following describes how SR-ISIS IPv4 or IPv6 or a SR-OSPF IPv4 tunnels are resolved.
When an SR-ISIS IPv4 or an SR-OSPF IPv4 tunnel is resolved to one or more RSVP-TE LSPs, then the following applications can resolve to the SR-ISIS or SR-OSPF tunnel in TTM:
L2 service FECs
BGP next hop of VPN IPv4/IPv6 prefixes
BGP next hop of EVPN routes
BGP next hop of IPv4 prefixes
BGP next hop of IPv6 prefixes (6PE)
next hop of a BGP LU IPv4 route
indirect next hop of IPv4 static routes
When an SR-ISIS IPv6 tunnel is resolved to one or more RSVP-TE LSPs, then the following applications can resolve to the SR-ISIS tunnel in TTM:
L2 service FECs
next hop of VPN-IPv4 and VPN-IPv6 over a spoke SDP interface using the SR tunnel
indirect next hop of IPv6 static routes
When an SR-ISIS IPv4 or an SR-OSPF IPv4 tunnel is resolved to one or more RSVP-TE LSPs, then the following applications cannot resolve in TTM to a SR-TE LSP that is using an SR-ISIS or SR-OSPF segment:
next hop of a BGP LU route
Next hops of BGP LU routes cannot resolve to LDP in TTM to a SR-TE LSP that is using an SR-ISIS or SR-OSPF segment because SR OS supports three levels of hierarchy in the data path and, because SR-TE LSP is a hierarchical LSP already, this makes the BGP-over-SRTE-over-RSVPTE a 4-level hierarchy. BGP keeps these BGP-LU routes unresolved.