The technologies that can be used as pseudo-wire can be Ethernet over MPLS, L2TPv3 or even GRE. There are two IETF standards track RFCs (RFC 4761 and RFC 4762) describing VPLS establishment.
VPLS is a Virtual Private Network (VPN) technology. In contrast to layer 2 MPLS VPNs or L2TPv3, which allow only point-to-point layer 2 tunnels, VPLS allows any-to-any (multipoint) connectivity.
In a VPLS, the Local Area Network (LAN) at each site is extended to the edge of the provider network. The provider network then emulates a switch or bridge to connect all of the customer LANs to create a single bridged LAN.
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