Cooperation with BGP

As shown in Figure 8, this feature can cooperate with BGP in an EVPN network. The Layer 3 Ethernet interfaces that directly connect a leaf node and a spine node borrow IP addresses with the subnet mask 255.255.255.255, for example, from loopback interfaces. For communication, the leaf node and the spine node learn the ARP entry of each other through LLDP.

Because the IP addresses of the interfaces that directly connect the spine node and the leaf node belong to different subnets, one node does not have the direct route to the other node. If BGP is used to transmit underlay network routes, BGP cannot perform correct route recursion. To resolve this problem, enable ARP direct route advertisement on the Layer 3 Ethernet interfaces that directly connect the spine node and the leaf node. One node generates a direct route to the other node and BGP can perform correct route recursion.

For information about EVPN, see EVPN Configuration Guide. For information about LLDP, see Layer 2—LAN Switching Configuration Guide. For information about BGP, see Layer 3—IP Routing Configuration Guide.