Resolving EVPN-MPLS Routes to Segment Routing Policy Tunnels

The next-hop resolution for all EVPN-VXLAN routes and for EVPN-MPLS routes without a color-extended community is unchanged by this feature.

When the resolution options associated with the auto-bind-tunnel configuration of an EVPN-MPLS service (vpls, b-vpls, r-vpls or E-pipe) allow sr-policy tunnels from TTM, then the next-hop resolution of EVPN-MPLS routes (RT-1 per-EVI, RT-2, RT-3 and RT-5) with one or more color-extended communities C1, C2, .. Cn (Cn = highest value) is based on the following rules.

Note: Contrary to section 8.8.2 of draft-filsfils-segment-routing-05, BGP only resolves a route with multiple color-extended communities to an SR policy using the color-extended community with the highest value.

If the next hop is IPv6 and there is an SR policy in TTMv6 for which end-point = BGP next-hop address and color = Cn, then use this tunnel to resolve the BGP next hop.
Otherwise, if the next hop is IPv4 or IPv4-mapped-IPv6 and there is an SR policy in TTMv4 for which end-point = BGP next-hop address (or the IPv4 address extracted from the IPv4-mapped IPv6 BGP next-hop address) and color = Cn, then use this tunnel to resolve the BGP next hop.
If no SR policy is found in the previous steps but there is a non-SR policy tunnel in TTMv4 (next hop is IPv4 or IPv4-mapped-IPv6) or TTMv6 (next hop is IPv6) that is allowed by the resolution options and for which endpoint = BGP next-hop address, then use this tunnel to resolve the BGP next hop if it has the highest TTM preference.