To solve the preceding issue, seamless MPLS was developed to extend MPLS to the access layer when used with MPLS-capable devices with higher performance. Because complicated VLAN configurations are required to associate with devices at the aggregation and core layers, using IP to forward packets at the access layer results in poor service scalability. Using the Internet Protocol (IP) to forward packets at the access layer, will result in low forwarding efficiency. This hierarchical deployment requires greater cooperation between different layers, makes network and service expansion more difficult, and increases operation costs for service providers.

The device then needs to obtain the original packets and add VLAN or QinQ tags to the packets before sending the packets to another layer, where the packets are encapsulated and transmitted over VPN within the destination layer. To transmit service packets from one layer to another, the VPN service needs to be terminated. Service packets that have been encapsulated and transmitted over a VPN tunnel can be sent only within one layer. A multi-service bearer network is deployed in a three layer hierarchy consisting of an access layer, aggregation layer, and core layer. Many service providers use MPLS-based 元VPN/L2VPN solutions to construct a multi-service bearer network. MPLS has been widely used on aggregation and core networks.

Traditional MPLS can converge multiple networks on an Ethernet-based infrastructure, which fully exerts the advantages of a single-forwarding model and reduces network construction costs. Seamless MPLS was developed out of a need for greater flexibility in scenarios where traditional MPLS overcomplicates network management.

Seamless meaning