EVPN-VXLAN: Asymmetric IRB routing with EVPN Route Type 2

This feature enables EVPN (MAC-VRF) with IRB (as forwarding interface) forward traffic using an asymmetric model. In asymmetric IRB, the lookup operation is asymmetric, and the ingress PE router performs three lookups, whereas the egress PE router performs a single lookup. That is, the ingress PE router performs a MAC lookup, followed by an IP lookup, followed by a MAC lookup again. The egress PE router performs just a single MAC lookup.