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 v(m, n, r) network. We first develop an analytical model for the blocking probability of the v(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 v(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≥θ(n log r/log log r) to achieve nonblocking for multicast connections. We also demonstrate that muting 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 v(m, n, r) network with a comparable cost to a permutation network can provide cost-effective support for multicast communication.