VXLAN EVPN Leaf and Spine – Part 2 – Overlay Setup

In this part we are going to look at the EVPN overlay setup of the topology. This allows the sharing of the layer 2 information learnt at each leaf switch. For this, we will use BGP.

Lets remind ourselves of the topology:

The BGP setup will have the spines as Route Reflectors to the topology so that we achieve a level of redundancy and all peerings will be iBGP. Two address families will be used for the exchange of NLRI, a standard IPv4 Unicast peering and then L2VPN EVPN.

First, we need to set the overlay to EVPN on all switches in the topology:

nv overlay evpn

BGP Configuration

The BGP configuration for the spines is:

router bgp 64500
  log-neighbor-changes
  address-family ipv4 unicast
  address-family l2vpn evpn
    retain route-target all
  template peer LEAF
    remote-as 64500
    update-source loopback0
    address-family ipv4 unicast
      send-community extended
      route-reflector-client
      soft-reconfiguration inbound
    address-family l2vpn evpn
      send-community
      send-community extended
      route-reflector-client
  neighbor 10.0.0.3
    inherit peer LEAF
  neighbor 10.0.0.4
    inherit peer LEAF
  neighbor 10.0.0.5
    inherit peer LEAF

And the configuration for the leaves:

router bgp 64500
  log-neighbor-changes
  address-family ipv4 unicast
  address-family l2vpn evpn
  template peer SPINE
    remote-as 64500
    update-source loopback0
    address-family ipv4 unicast
      send-community extended
      soft-reconfiguration inbound
    address-family l2vpn evpn
      send-community
      send-community extended
  neighbor 10.0.0.1
    inherit peer SPINE
  neighbor 10.0.0.2
    inherit peer SPINE

We can verify the configuration on the spines by checking the neighbour states:

spine-1(config)# show bgp ipv4 unicast summary 
BGP summary information for VRF default, address family IPv4 Unicast
BGP router identifier 10.0.0.1, local AS number 64500
BGP table version is 4, IPv4 Unicast config peers 3, capable peers 3
0 network entries and 0 paths using 0 bytes of memory
BGP attribute entries [0/0], BGP AS path entries [0/0]
BGP community entries [0/0], BGP clusterlist entries [0/0]

Neighbor        V    AS MsgRcvd MsgSent   TblVer  InQ OutQ Up/Down  State/PfxRcd
10.0.0.3        4 64500      10      10        4    0    0 00:01:13 0         
10.0.0.4        4 64500      10      10        4    0    0 00:01:10 0         
10.0.0.5        4 64500      10      10        4    0    0 00:01:06 0         
spine-1(config)# show bgp l2vpn evpn summary 
BGP summary information for VRF default, address family L2VPN EVPN
BGP router identifier 10.0.0.1, local AS number 64500
BGP table version is 5, L2VPN EVPN config peers 3, capable peers 3
0 network entries and 0 paths using 0 bytes of memory
BGP attribute entries [0/0], BGP AS path entries [0/0]
BGP community entries [0/0], BGP clusterlist entries [0/0]

Neighbor        V    AS MsgRcvd MsgSent   TblVer  InQ OutQ Up/Down  State/PfxRcd
10.0.0.3        4 64500      10      10        5    0    0 00:01:25 0         
10.0.0.4        4 64500      10      10        5    0    0 00:01:21 0         
10.0.0.5        4 64500      10      10        5    0    0 00:01:17 0          

spine-2(config)# show bgp ipv4 unicast summary 
BGP summary information for VRF default, address family IPv4 Unicast
BGP router identifier 10.0.0.2, local AS number 64500
BGP table version is 4, IPv4 Unicast config peers 3, capable peers 3
0 network entries and 0 paths using 0 bytes of memory
BGP attribute entries [0/0], BGP AS path entries [0/0]
BGP community entries [0/0], BGP clusterlist entries [0/0]

Neighbor        V    AS MsgRcvd MsgSent   TblVer  InQ OutQ Up/Down  State/PfxRcd
10.0.0.3        4 64500      10      10        4    0    0 00:01:43 0         
10.0.0.4        4 64500      10      11        4    0    0 00:01:42 0         
10.0.0.5        4 64500      10      10        4    0    0 00:01:37 0         
spine-2(config)# show bgp l2vpn evpn summary 
BGP summary information for VRF default, address family L2VPN EVPN
BGP router identifier 10.0.0.2, local AS number 64500
BGP table version is 5, L2VPN EVPN config peers 3, capable peers 3
0 network entries and 0 paths using 0 bytes of memory
BGP attribute entries [0/0], BGP AS path entries [0/0]
BGP community entries [0/0], BGP clusterlist entries [0/0]

Neighbor        V    AS MsgRcvd MsgSent   TblVer  InQ OutQ Up/Down  State/PfxRcd
10.0.0.3        4 64500      10      10        5    0    0 00:01:49 0         
10.0.0.4        4 64500      10      11        5    0    0 00:01:48 0         
10.0.0.5        4 64500      10      10        5    0    0 00:01:43 0         

So we now have the underlay and overlay configured, we can move onto the VNI configuration in the next part.