PERFORMANCE EVALUATION OF MULTICAST PROTOCOLS
In this paper, we report an analytic comparison of control bandwidth overheads (CBOs) for different implementations of protocol independent multicast (PIM) variants in a hierarchical network environment using combinatorial technique. We find that over networks with several numbers of hierarchies PIM variants can have significantly different CBO per group member. In particular, the modified dense mode (DM) with state refresh (DMSR) typically has significantly lower CBO per group member than DM with flood and prune (DMFP) mechanism. Also studied is the precise measure of the relative performance between sparse mode (SM) and source specific multicast (SSM) protocols. The results show that the overhead costs of these protocols depend strongly on the choice of the protocol and the operating conditions present. Our findings show that at low network utilisation (i.e., a sparse network) there is a great sensitivity as SM is by far the most efficient protocol. The performance difference between SSM and DMSR protocols is also significant as SSM is better than DMSR for small groups while for large groups DMSR is superior. These results provide useful information to the network community, particularly network designers, integrators and users.