Patent ID: 7310335

Claim:
A method for communicating multicast group membership information in a network between a plurality of routers in a multicast group, the method comprising: reporting routing tree information from each of the plurality of routers reports to other routers of said plurality of routers, wherein the routing tree information comprises a source tree for a unicast routing protocol; receiving update information at a second router in the network from a first router, said update information comprising update information on a multicast group and a network address of said first router; using said update information to indicate that said first router is becoming a member of said multicast group; determining, based at least in part on said update information and the routing tree information reported by said first router, whether said second router is to transmit said update information so that all members of said multicast group remain connected, by determining if said source tree reported by said first router has said second router as a root of a subtree from which said first router is excluded, and if at least one neighbor router of said second router in said subtree is not a member of said multicast group; and in response to a positive determination, transmitting said update information from said second router to said at least one neighbor router of said second router.