An Heuristic for Lower Cost Multicast Routing in the Internet.

Some multicast applications require high bandwidth and bounded delay (eg Video-conferencing). The general problem of constructing bounded delay minimal cost multicast trees uses two link metrics (cost and delay) and is NP-complete. A number of heuristics have been developed, most of which tend to have a high order of time complexity. Our heuristics achieve good results with low time-complexity and we believe that they are adaptable to a number of other multicasting scenarios. Current Internet multicasting protocols use either link-state or distance vector routing to construct multicast trees that have minimum path delays. Tree cost is ignored. When our heuristics are applied using a single link metric, they achieve minimum delay path multicast trees of lower cost than those constructed using Dijkstra's shortest path algorithm. The cost savings achieved by one of our heuristics is such that it can be considered as a candidate for use in distributed muticast protocols, such as MOSPF, as an alternative to Dijkstra's algorithm.