Overlay - iBGP Control Plane

Spine and Leaf BGP Configuration

We set up a peer template, as the configuraion does not differ between the leaf switches.

router bgp 65000
  template peer LEAF
    remote-as 65000
    update-source loopback0
    address-family l2vpn evpn
      send-community
      send-community extended
      route-reflector-client 
  neighbor 192.0.2.3
    inherit peer LEAF
  neighbor 192.0.2.4
    inherit peer LEAF

We use a template for the leaf switches as well:

router bgp 65000
  template peer SPINE
    remote-as 65000
    update-source loopback0
    address-family l2vpn evpn
      send-community
      send-community extended
  neighbor 192.0.2.1
    inherit peer SPINE
  neighbor 192.0.2.2
    inherit peer SPINE

One item to notice here: we've only enabled the l2vpn evpn address family on the peering. The standard ipv4 unicast address family is not even enabled. We can see this by looking at the capabilities passed between the neighbours. Apart from the dynamic capability, route refresh, 'old' Cisco route refresh, graceful restart and 4-byte ASN, the only address family capability is the 'L2VPN EVPN' address family. This is carried in the multiprotocol extentsions capability with an AFI of 1 and a SAFI of 70.

pseudo-spine1_leaf1# show bgp all neighbors 
BGP neighbor is 192.0.2.3, remote AS 65000, ibgp link, Peer index 3
...
  Neighbor capabilities:
  Dynamic capability: advertised (mp, refresh, gr) received (mp, refresh, gr)
  Dynamic capability (old): advertised received
  Route refresh capability (new): advertised received 
  Route refresh capability (old): advertised received 
  4-Byte AS capability: advertised received 
  Address family L2VPN EVPN: advertised received 
  Graceful Restart capability: advertised received