Provider link state bridging

Wide area communications technology has been challenged to virtualize large numbers of Ethernet LAN segments. This is a consequence of a mismatch between the broadcast nature of the LAN segment and the extremely constrained connectivity implied by the p2p connections or tunnels available in the WAN environment, which have been combined to create virtual LAN segments. PBB-TE has been a practical demonstration of how filtering applied to a broadcast media can result in a connection. This article introduces provider link state bridging (PLSB), which adds a control plane to the PBB data plane in order to extend the techniques for manipulation of Ethernet bridges for unicast paths pioneered by PBB-TE. PLSB solves the problem of largescale virtualization of LAN segments over an Ethernet infrastructure by applying advances in computation performance to the multicast capabilities inherent in the Ethernet data plane. The result is that the fundamental primitives of connectivity today, the broadcast LAN segment and the connection, can be virtualized in a scalable manner on a common (but substantially larger and better utilized) Ethernet-based infrastructure.