Efficient multicast in heterogeneous networks of workstations

This paper studies the problem of efficient multicast in heterogeneous networks of workstations (HNOWs) using a parameterized communication model. This model associates a sending overhead and a receiving overhead with each node as well as a network latency parameter. The problem of finding optimal multicasts in this model is known to be NP-complete in the strong sense. Nevertheless, we show that for two different properties that arise in typical HNOWs, provably near-optimal and optimal solutions, respectively, can be found in polynomial time. Specifically, we show the following two results: when the ratios of receiving overhead to sending overhead among the nodes is bounded by constants, solutions within a bounded ratio of optimal can be found in time O(nlogn). Secondly, if the number of distinct types of workstations is fixed then optimal solutions can be found in polynomial time. These results provide a practical means of finding optimal and provably near-optimal multicast schedules in a large class of frequently occurring heterogeneous networks of workstations.