A hybrid overlay network for video-on-demand

On-demand video streaming through overlay networks has received much attention recently. While a tree topology is often advocated in such systems, it suffers from discontinuous playback under the highly dynamic Internet environment with frequent node joins and leaves. On the other hand, gossip protocols using random message dissemination, though robust, fail to meet the real-time demands for streaming applications. In this paper, we propose HON, a hybrid overlay network protocol, which combines the best features of these two approaches for on-demand streaming: low delay with a regular tree topology, and robust delivery with random switching among multiple paths, thus making effective use of the available bandwidth in the network We design an adaptive tree construction and gossip management algorithm for HON, and evaluate its performance under various settings. The results demonstrate that HON is quite robust in the presence of local and global bandwidth fluctuations. As compared to pure tree-based overlay VOD system, it achieves much lower and stable segment missing rates, even under highly dynamic network conditions.