BAD: bandwidth adaptive dissemination or (the case for BAD trees)

In this paper, we present BAD, an application-level multicast infrastructure. BAD is designed to improve the performance of multicast dissemination trees, under both a static and a dynamic environment, where the effective bandwidth of the network links changes with time. Its main goal is to improve the data rate that end users perceive during a multicast operation. BAD can be used for the creation and management of multicast groups. It can be deployed over any DHT retaining its fundamental advantages of bandwidth improvement. BAD consists of a suit of algorithms for node joins/leaves, bandwidth distribution to heterogeneous nodes, tree rearrangement and reduction of overhead. We have implemented BAD within the FreePastry system. We report on the results of a detailed performance evaluation which testifies for BAD's efficiency and low overhead. Specifically, our experiments show that the improvement on the minimum bandwidth ranges from 40% to 1400% and the improvement on the average bandwidth ranges from 60% to 250%