Arista BGP Peering Options (4) - IPv4 NRLI over IPv6 NH

This blog is about the v4 NRLI over v6 NH. Based on Arista 4.17.0F TOI, this feature comprises 2 parts:

• IPv4 forwarding on IPv6 interface
• IPv6 NRLI with IPv6 NH

Compared with previous configurations, 2 configures are needed:

1. IPv4 forwarding on IPv6 interface, which is enabled by "ip routing ipv6 interfaces  vrf v3"
2. neighbor <ipv6Nei> next-hop address-family ipv6 originate

Another way of 2nd part is to enable "bgp next-hop address-family ipv6". But in the above topology, the NRLI is originated directly, so have to put originate. 

From the output of "show ip route", you can see the v4 route's NH is the ipv6 address

R1.lp231.20:13:59(config-router-bgp-vrf-v3)#sh ip route bgp detail

VRF: v3

 B E   103.2.2.0/24 [200/0]

       via 12:12:103::2, Vlan103

R1.lp231.20:14:07(config-router-bgp-vrf-v3)#sh ip bgp 103.2.2.0

BGP routing table information for VRF v3

Router identifier 103.2.2.2, local AS number 1

BGP routing table entry for 103.2.2.0/24

 Paths: 1 available

  2

    12:12:103::2 from 12:12:103::2 (103.2.2.2)

      Origin IGP, metric 0, localpref 100, IGP metric 1, weight 0, received 00:18:46 ago, valid, external, best

      Rx SAFI: Unicast