Performance analysis and simulation of multicast networks

In this paper, we look into the issue of supporting multicast in the well-known three-stage Clos network or /spl nu/(m, n, r) network. We first develop an analytical model for the blocking probability of the /spl nu/(m, n, r) multicast network, and then study the blocking behavior of the network under various routing control strategies through simulations. Our analytical and simulation results show that a /spl nu/(m, n, r) network with a small number of middle switches m, such as m=n+c or dn, where c and d are small constants, is almost nonblocking for multicast connections, although theoretically it requires m/spl ges//spl Theta/ (nlog r/log log r) to achieve nonblocking for multicast connections. We also demonstrate that routing control strategies are effective for reducing the blocking probability of the multicast network. The best routing control strategy can provide a factor of 2 to 3 performance improvement over random routing. The results indicate that a /spl nu/(m, n, r) network with a comparable cost to a permutation network can provide cost-effective support for multicast communication.