EVPN gateway support for all-active (A-A) multihoming adds a new redundancy model to our multi-domain EVPN solution introduced in [1]. This deployment model introduces the concept of a WAN Interconnect Ethernet Segment identifier (WAN I-ESI) which is shared by gateway nodes within the same domain (site) and set in MAC-IP routes that cross domain boundaries. The WAN I-ESI allows the gateway’s EVPN neighbors to form L2 and L3 overlay ECMP on routes re-exported by the gateway.

This feature extends the multi-domain EVPN VXLAN feature introduced to support interconnect with EVPN MPLS networks. The following diagram shows a multi-domain deployment with EVPN VXLAN in the data center and EVPN MPLS in the WAN. Note that this is the only supported deployment model, and that an EVPN MPLS network cannot peer with an EVPN MPLS network.

In EOS 4.22.0F, EVPN VXLAN all active multi homing L2 support is available. A customer edge (CE) device can connect to