A Congestion Control Algorithm for Tree-based Reliable Multicast Protocols

This paper contains a detailed description of the congestion control algorithm of TRAM, a tree-based reliable multicast protocol. This algorithm takes advantage of regular acknowledgements from the receivers that propagate back to the sender via the repair tree. This scalable feedback mechanism is used to collect receiver credits. Complementing the windowing mechanism, packet transmission is smoothed by using a data rate commensurate with the window size. Additional details, such as how to prune slow receivers, and how to implement the rate scheduler on non-real-time systems are also discussed. The performance of the congestion control algorithm is then evaluated in extended LANs, and wide area networks. The fairness of bandwidth-sharing with other (TCP) traffic is also evaluated.