A scaleable multicast routing algorithm for IP-ATM-IP networks

Dynamic multicasting is needed in many military communication systems using IP-over-ATM networking. This paper considers transmission of IP multicast packets over a large IP-ATM-IP communication network and presents a multicast routing algorithm called multipoint-to-multipoint routing path with branches (MMRPWB) for the ATM portion of this network. The algorithm presents, for each multicast group, steps for establishing a single multicast routing path that can be used by all sources (senders) in this multicast group to multicast messages to all other group members simultaneously. Generation of the path starts at an arbitrary member node that sends a routing cell through the network. On receiving a copy of the cell a node can decide to join the path if it is a member of the multicast group. Otherwise it retransmits the cell forward. The algorithm eliminates the need for the establishment of individual point-to-multipoint routes for each sender member of a multicast group and reduces overall number of SVCs required. The resulting multipoint-to-multipoint path uses only point-to-point SVCs and hence eliminates the problems associated with using point-to-multipoint SVCs. It also eliminates the need for dynamic IP to ATM address resolution. The performance of this multipoint-to-multipoint path has been shown to be superior to those of multicast routes established by using minimal spanning tree (MST), multicast open shortest path first (MOSPF) and core based tree (CBT) algorithms under similar conditions in terms of delay, join and leave times, robustness, scaleability and difficulties of physical implementation.