Seamless MPLS is a bearer technique that extends MPLS techniques to access networks. Seamless MPLS establishes an E2E LSP across the access, aggregation, and core layers. All services can be encapsulated using MPLS at the access layer and transmitted along the E2E LSP across the three layers.
With current trends moving towards a flat network structure, metropolitan area networks (MANs) are steadily evolving into the Ethernet architecture, which calls for the application of MPLS on the MAN and access networks. To meet this requirement, seamless MPLS was developed. Seamless MPLS uses existing BGP, IGP, and MPLS techniques to establish an E2E LSP across the access, aggregation, and core layers, allowing end-to-end traffic to be encapsulated and forwarded using MPLS.