Performance of layered multicast video

The design of congestion control protocols for multicast applications presents various challenges. This paper studies the use of the layered approach for congestion control for video multicasting in IP networks. Several issues that have a direct impact on the allocation of bandwidth between competing flows of layered multicast video and transmission control protocol (TCP) are investigated: in particular, (1) the type of congestion control mechanisms employed by layered multicast viedo protocols: (2) the effect of the distribution of video traffic across layers in layered multicast video: and (3) the effect of variable bitrate (VBR) viedo on fairness to TCP. The study shows that bandwidth allocation between layered video and TCP is affected by all three of these issues and that this is true irrespective of the actual implementation of a specific layered multicast protocol. It is also shown that correcting the behaviour of layered multicast video towards TCP comes at the expense of instability in video quality and a poor link utilization.