Eliminating Bottlenecks in Overlay Multicast

Recently many overlay multicast systems have been proposed to overcome limited availability of IP multicast. Because they perform multicast forwarding without support from routers, data may be delivered multiple times over the same physical link, causing a bottleneck. This problem is more serious for applications demanding high bandwidth such as multimedia distribution. Although such bottlenecks can be removed by changing overlay topology, a näıve approach may create bottlenecks in other parts of the network. In this paper, We propose an algorithm that removes all bottlenecks caused by the redundant data delivery of overlay multicast, detecting such bottlenecks using a wavelet-based technique we recently proposed. In a case where the source rate is constant and the available bandwidth of each link is not less than the rate, our algorithm guarantees that every node receives at the full source rate. Simulation results show that even in a network with a dense receiver population, our algorithm finds a tree that satisfies all the receiving nodes while other heuristicbased approaches often fail.