Developing a multicast metric

To further advance the deployment of multicast, many consider it necessary to provide a quantitative measure of the potential benefit of employing multicast rather than unicast. We approach this problem in three ways. First, we propose a rudimentary metric that can provide a reasonable measure of the benefit achieved by an active group using multicast instead of unicast. Second, we discuss many of the issues inherent in developing multicast metrics and how these issues may be addressed to improve the accuracy of our model. Third, we consider how characteristics of network topology and group distribution might offer a predictive estimate for the proposed metric. In general, we identify two rules for evaluating the efficiency of multicast: (1)multicast efficiency increases as the average path length increases, and (2)fan-out close to the source decreases multicast’s efficiency.