| This work proposes an edge-node multicast overlay to create a tree capable of performing point to multipoint distribution of real time video (i.e., a videoconference) with a hard upper bound on end-to-end delay. By moving the tree configuration, replication, and network monitoring to the edge routers instead of end systems, the trees can be constructed using the knowledge of overlay link bandwidths and latencies. As participants join the videoconference, several possible tree configurations are considered and a score based on latency and bandwidth utilization is assigned to each. The configuration with the highest score is chosen and constructed. Simulations are run in which both MPEG videos, and videos from a new high-quality, low-latency video codec named VCLAN are sent through a congested network. The stress on the network links is evaluated and the evaluation shows that the videos can be successfully transmitted without over-stressing the most highly utilized links. Analysis of the running time shows that this algorithm is useful for videoconferences involving a small number of participating LANs, though multiple recipients may be on a single LAN.; It is shown that by giving appropriate weights to both bandwidth and latency, performance characteristics similar to native IP multicast can be achieved. In certain cases, the new algorithm can out-perform IP multicast by routing around congested links. |
