EVPN E-LAN Overview
An Ethernet LAN (E-LAN), defined by the Metro Ethernet Forum (MEF), is a multipoint-to-multipoint transparent Layer 2 (L2) VLAN service that connects two or more user network interfaces (UNIs). The E-LAN provides full mesh connectivity for the UNI sites. A UNI is the dividing point between the responsibilities of the service provider and subscriber. Every UNI can communicate with any other UNI that is connected to the E-LAN service.
Ethernet VPN (EVPN) E-LAN is a framework for delivering multipoint-to-multipoint VPN service with the EVPN signaling mechanisms. E-LAN service allows service providers to offer services that manage the L2 learning very efficiently. In a multihoming scenario, the broadcast, unknown unicast, and multicast (BUM) traffic is handled by the provider edge (PE) device, acting as a designated forwarder (DF). The learned information is redistributed to other PEs in the network. The multihomed customer edge (CE) device connects a customer site to two or more PE devices providing redundant services.
The MEF standard has two different services for EVPN E-LAN:
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Ethernet Private LAN (EP-LAN), which offers a multipoint-to-multipoint ethernet virtual connection (EVC) between dedicated UNIs. EP-LAN is a port-based service.
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Ethernet Virtual Private LAN (EVP-LAN), which offers VLAN based service multiplexing, which means EVCs are paired per UNI.