AMCA: an Active-based Multicast Congestion Avoidance Algorithm

Many works have recently addressed the issue of con-gestion control for multicast communications and the prob-lem is known to be highly complex. Scalability, responsive-ness, stability and fairness with TCP are some of the re-quired properties. In this paper, we present a congestion avoidance scheme for bulk data distribution called AMCA (Active-based Multicast Congestion Avoidance algorithm) that tries to meet these properties. We use the active net-working technology to perform on a per-section dialogue to probe for available bandwidth along a multicast tree. The solution uses the RTT variations experienced by every branch to estimate the congestion situation in the multicast tree. The physical multicast tree is also used to appropri-ately aggregate the RTT variations at intermediate nodes before they reach the source. Simulations show that AMCA converges, makes use of the available bandwidth and reacts rapidly to dynamic changes while being TCP-fair. 1