Method and apparatus for transparently bridging traffic across wide area networks

Abstract

A technique for logically connecting local communications networks (CNs) that may be separated by wide area networks containing routers and other network components. A logical link is formed between two devices called tunnelers, such that, once a tunnel has been established between two CNs, other devices on the CNs can communicate. The tunneling mechanism of the invention requires that each CN have only one active tunneler at any particular time, referred to as the designated tunneler, and each of the tunnelers is configured to have knowledge of the identities of the other tunnelers. A tunnel is established after a successful exchange of messages between two tunnelers, and then traffic may be forwarded through the tunnel in a transparent manner. The tunneling mechanism permits messages to be forwarded between CNs separated by a wide area network containing routers. Moreover, the mechanism permits filtering of traffic, such that only selected types of traffic, or messages for selected destinations or from selected sources, are forwarded through tunnels. The tunneling mechanism inherently precludes the formation of closed communication loops. An alternate embodiment of the invention optimizes the configuration process for particular network topologies.