Patent ID: 8400945

Claim:
A method, comprising: receiving a first link-state advertisement in a network environment in which a plurality of hub routers and a plurality of spoke routers operate, wherein signaling in the network environment is transparent and backwards compatible to the plurality of the spoke routers, wherein the signaling uses a B-bit if the plurality of hub routers are all area border routers and an opaque link-state advertisement if the plurality of hub routers are not area border routers; and computing a shortest path tree based on the first link-state advertisement, wherein said shortest path tree identifies hub router-to-hub router, hub router-to-spoke router, spoke router-to-spoke router, and spoke router-to-hub router link types in the network environment and then eliminates the spoke router-to-hub router link types for provisioning in a routing table, and wherein the shortest path tree is truncated at the hub routers for particular links leading from the spoke routers to the hub routers and not vice versa.