EVPN multihoming in VPLS services

EVPN multihoming implementation is based on the concept of the ethernet-segment. An ethernet-segment is a logical structure that can be defined in one or more PEs and identifies the CE (or access network) multihomed to the EVPN PEs. An ethernet-segment is associated with port, LAG, PW port, or SDP objects and is shared by all the services defined on those objects. In the case of virtual ESs, individual VID or VC-ID ranges can be associated with the port, LAG, or PW port, SDP objects defined in the ethernet-segment.

Each ethernet-segment has a unique Ethernet Segment Identifier (ESI) that is 10 bytes long and is manually configured in the router.

Note: The ESI is advertised in the control plane to all the PEs in an EVPN network; therefore, it is very important to ensure that the 10-byte ESI value is unique throughout the entire network. Single-homed CEs are assumed to be connected to an Ethernet-Segment with esi = 0 (single-homed Ethernet-Segments are not explicitly configured).

This section describes the behavior of the EVPN multihoming implementation in an EVPN-MPLS service.