Rate-based congestion control for tree-based reliable multicast

Although a few rate-based congestion control algorithms have been proposed for multicast, the effectiveness of these protocols on tree-based reliable multicast has not been evaluated. In addition, the tree-based recovery structure of reliable multicast could be exploited to enhance the performance and/or scalability of the congestion control scheme. In this paper, we extend TFMCC, a rate-based congestion control scheme designed for group-based (unreliable) multicast, to support tree-based reliable multicast. We first conducted experiments to investigate how network parameters may affect the sharing of bandwidth between TFMCC and TCP. Observations drawn from these experiments allowed us to avoid the situations in which multicast flows using TFMCC may be disadvantaged by TCP flows. Secondly we extend TFMCC to support tree-based reliable multicast. Specifically, we propose the use of the tree-based structure to calculate RTTs and to consolidate rate values at the designated receivers (DRs) in a scalable manner; and the calculation of retransmission rates of the DRs. Our simulation results show that the proposed protocol is effective, TCP-friendly and responsive to network conditions.