Hierarchical multicast routing in ATM networks

In this paper, we extend the hierarchical PNNI (private network node interface or private network network interface) point-to-point routing protocols [Dykeman, 1995] to support multicast routing in ATM networks. Our idea is based on the core-based tree idea for inter-domain multicast routing in the Internet [Ballardie et al., 1993]. Our idea uses multiple core nodes connected on a backbone tree. The destination nodes attach to the core nodes using the shortest path. Our algorithm is scalable because the multicast tree is shared among all senders. Also, only the core node information has to be flooded within each peer group. Our algorithm supports dynamic changes to the set of destinations. The backbone tree itself can be reconstructed depending on the current link and node states, thus, guaranteeing quality-of-service requirements. The cost of the multicast tree built incrementally for a given set of destinations is comparable to the cost of the Steiner tree constructed using standard heuristics. Using simulations, we show that the process of addition or deletion nodes is simplified, thereby reducing overheads. Moreover, the routing algorithm is recursive, that is, the nodes at each level of hierarchy execute the same algorithm. This makes the algorithm suitable for a distributed implementation.