Multicast tree computation in networks with multicast incapable nodes

Multicast transmission offers a bandwidth efficient solution for delivering media content to multiple destinations over the Internet. However, in many existing networks, some (if not all) nodes do not support multicast, i.e., they cannot create multiple outgoing flows with one incoming data flow. In this paper, the authors propose an algorithm for multicast tree computation in networks with multicast incapable nodes. Paths that originate at the source and traversing all destinations are computed first; if such paths cannot be found, destinations are partitioned into subsets and traverse paths are computed over each subset, which is executed recursively until feasible trees can be built based on traverse paths found or no further partition is possible. Two procedures for traverse path computation are presented and their respective advantages are discussed, in terms of both complexity and solution optimality. The algorithm is also shown to be very effective in finding multicast trees even if only a few multicast capable nodes exist in the network.