Convergence in a Multihomed EVPN-MPLS Network

Multihoming a CE device to two or more PE devices on an EVPN MPLS network provides redundant connectivity and allows the network to continue providing services when one of the PE devices fail or if there is a PE-CE link failure. When the multihomed connection from a CE device to a PE device fails, the devices in the networks updates the EVPN routes, including any MAC routes and next hop entries in their forwarding table

Figure 1 shows a simple EVPN topology with CE1 multihomed to PE1 and PE2 with an Ethernet segment. If the connection from CE1 to PE1 fails and similarly when the connection from CE1 to PE1 is restored, PE1 will withdraw MAC routes from PE2 and PE3, while PE2 and PE3 will remove the MAC routes that they learned from PE1. EVPN egress link protection adds backup next hops on the multihomed PE devices and is used to support fast reroute (FRR) in the network. When you enable EVPN egress link protection, you can improve the convergence time in the EVPN MPLS network and reduce traffic loss when the link to a PE device fails.

Figure 1: Simple EVPN MPLS Topology

To enable EVPN egress link protection, include evpn-egress-link-protection at the [edit routing-options forwarding-table] hierarchy level on all multihomed PE devices in the EVPN network.

The following example shows a sample configuration for evpn egress link protection.