MCA: an end-to-end multicast congestion avoidance scheme with feedback suppression

In this paper, we propose MCA, an end-to-end multicast congestion avoidance scheme with feedback suppression. Congestion avoidance [7] is different from congestion control in the sense that our scheme detects and responds to network congestion without necessarily inducing packet loss. Our scheme is a single-rate scheme and operates end-to-end, i.e. the sending rate is controlled by the source based on feedback from the most congested receiver and does not expect packet marking or other support from intermediate nodes. We design it to be robust under both lossless and lossy situations. Congestion is detected at receivers using the concept of “accumulation” (the number of buffered bits of a flow inside the network) and simple thresholding techniques proposed in our recent unicast work [22]. For the purposes of choosing representative (the most congested receiver) by the source and suppressing feedback by receivers, each receiver maintains its Good Throughput Rate At Congestion (GTRAC) (the product of receiving rate during congestion epochs and 1− f , where f is congestion occurrence frequency). In this way, receivers do not need to continuously (either densely or sparsely) exchange packets with the sender (e.g. to measure RTT). Therefore, MCA is scalable for large-size groups. We evaluate the design and demonstrate the performance of MCA using detailed ns-2 simulations.