A high-speed routing search is realized by a hierarchial routing table, while a conventional network having a hierarchial network as a backbone performs conventional operations without being aware of the hierarchial backbone network, in a mixed environment of the hierarchial and non-hierarchial networks,...http://www.google.co.uk/patents/US20020075872?utm_source=gb-gplus-sharePatent US20020075872 - Routing control method and apparatus thereof in a mixed environment of a hierarchial network and a non-hierarchial network
