GSC: a generic source-based congestion control algorithm for reliable multicast

Abstract

This paper presents a simple, generic source-based end-to-end multicast congestion control (GSC) algorithm for reliable multicast transport (RMT) protocols. The algorithm is completely implemented at the source and leverages the reverse control information flow in RMT protocols like PGM or RMTP. Specifically, it does not introduce any new control traffic or new fields in RMT protocol headers. It partially addresses the drop-to-zero problem by introducing a robust, adaptive time-filter based upon RTT (round trip time) estimates collected by observing NAK traffic. This solution allows it to scale for large multicast groups while being adaptive to congestion situation changes in any part of the tree. The algorithm is friendly to TCP in terms of competition for bandwidth shares. The scheme has minimal control traffic requirements and weak RTT estimation requirements.