domain. Similarly, the border nodes decapsulate the traffic from the BGP EVPN VXLAN fabric and bridge it with the corresponding IEEE 802.1Q tag to the access switches. The interface on the border VTEP that faces the external interface can be either an access or a Trunk port. The external interface can belong to either a Layer 2 switch or a firewall. If you connect the network to an external Layer 2 switch through two border VTEPs, it represents a dual connection. In such cases, STP does not propagate over the BGP EVPN VXLAN fabric by default.
Note Layer 2 External connectivity with VPLS over MPLS Network External connectivity with VPLS networks or VPLS handoff is achieved when a border VTEP or multiple border VTEPs establish a connection with the VPLS network. The border nodes act as the provider edge (PE) devices in the VPLS network and as VTEPs in the EVPN VXLAN network. BGP EVPN VXLAN supports VPLS handoff in the form of VPLS stitching through either an access VFI or an access pseudowire on the VLAN on the border VTEP. The access pseudowires and the pseudowires in the access VFI function as the access ports in the EVPN VXLAN network.
The BGP EVPN VXLAN fabric treats the MAC addresses learned on the pseudowires as locally learned MAC addresses. It advertises these MAC addresses within the fabric as EVPN type 2 routes. The pseudowires are in a different split horizon group compared to the EVPN VXLAN network. Therefore, BUM traffic floods between both the EVPN VXLAN and VPLS networks. Route Leaking between EVPN-enabled VRF and Global Routing Tables The route leaking feature provides the import and export of routes between an EVPN-enabled Virtual Routing and Forwarding (VRF) Table and the Global Routing Table (GRT).
By enabling the import or export of the EVPN learned routes into the GRT, the border node provides access to services such as DNS or DHCP to the hosts in the fabric. Routes that are imported from GRT to VRF can subsequently be imported to EVPN using the import {ipv4|ipv6} unicast map allow-evpn command. Routes that are imported from EVPN to IP VRF can subsequently be exported to GRT using the export {ipv4|ipv6} unicast map allow-evpn command. You can further filter the imported routes using route-maps. A route-map contains the match conditions that define which of the routes from the import or export tables are allowed into the target routing table.
This reduces the risk of unintended import or export of routes between the tables and helps contain the table sizes and advertisements. How to Configure EVPN VXLAN External Connectivity This section provides information about how to configure external connectivity between an EVPN VXLAN network and an external Layer 2 or Layer 3 network. You must configure EVPN VXLAN Layer 2 and Layer 3 overlay networks before you configure external connectivity. See Configuring EVPN VXLAN Integrated Routing and Bridging for detailed steps. Note Configuring EVPN VXLAN External Connectivity Route Leaking between EVPN-enabled VRF and Global Routing Tables Configuring EVPN VXLAN External Connectivity 6