The VPLS architecture proposed in RFC 4762, Virtual Private LAN Services Using LDP Signaling specifies the use of provider equipment (PE) that is capable of learning, bridging, and replication on a per-VPLS basis. The PE routers that participate in the service are connected using MPLS Label Switched Path (LSP) tunnels in a full-mesh composed of mesh SDPs or based on an LSP hierarchy (Hierarchical VPLS (H-VPLS)) composed of mesh SDPs and spoke-SDPs.
Multiple VPLS services can be offered over the same set of LSP tunnels. Signaling specified in RFC 4905, Encapsulation methods for transport of layer 2 frames over MPLS is used to negotiate a set of ingress and egress VC labels on a per-service basis. The VC labels are used by the PE routers for demultiplexing traffic arriving from different VPLS services over the same set of LSP tunnels.
VPLS is provided over MPLS by:
connecting bridging-capable provider edge routers with a full mesh of MPLS LSP tunnels
negotiating per-service VC labels using Draft-Martini encapsulation
replicating unknown and broadcast traffic in a service domain
enabling MAC learning over tunnel and access ports (see VPLS MAC learning and packet forwarding)
using a separate FDB per VPLS service