Explicit rate multicast congestion control
In this article, we propose a new single-rate end-to-end multicast congestion control scheme called Explicit Rate Multicast Congestion Control (ERMCC) based on a new metric, TRAC (Throughput Rate At Congestion). ERMCC can be implemented only at the source and the receivers of the multicast tree. ERMCC achieves an O(1) memory complexity to maintain state information at source and receivers; requires only simple computations; and does not necessitate measurement of RTTs from all receivers to the source. ERMCC does not suffer from the drop-to-zero problem and is very effective with feedback suppression (achieves 95% suppression). Furthermore, with proper adjustment of its rate adaptation parameters, ERMCC achieves TCP friendliness only on the path to the slowest receiver. Theoretical analysis of the scheme performance is provided, and simulations have shown that ERMCC outperforms PGMCC and TFMCC under most situations. We have also implemented ERMCC over UDP and successfully run it on real testbed systems in Emulab with very good results. In addition to this implementation, we also obtained very good results in large-scale simulation tests of ERMCC.