Generic Models for Evaluating Multicast Protocols in Hierarchical Networks

In this paper we derive analytic models for evaluating the performance of multicast protocols in hierarchical networks. Specifically, we investigate the properties and costs of setting up and maintaining a multicast distribution tree by different variants of protocol independent multicast (PIM) in two scenarios; where the data source is outside the networks and secondly, where the data source is part of the networks. We derive our models on the assumptions that the networks are symmetrical and nodes responses are not delayed and the maximum amount of merging possibly takes place. In practice, this means that all round-trip times need to be less than the inter-packet arrival times. The symmetry of the networks enables us to assign equal value to both down and up links and then use the number of links traversed by control message packets to compute the performance of the PIM variants. The results of our numerical investigation confirm that in most mean group sizes the PIM-sparse mode (PIM-SM) is more cost-effective than the PIM-dense mode with flood and prune mechanism (PIM-DMFP).