Sharing Multicast Videos Using Patching Streams

摘要

The access patterns of most information systems follow the 80/20 rules. That is, 80% of the requests are for 20% of the data. A video server can take advantage of this property by waiting for requests and serving them together in one multicast. This simple strategy, however, incurs service delay. We address this drawback in this paper by allowing clients to receive the leading portion of a video on demand, and the rest of the video from an ongoing multicast. Since clients do not have to wait for the next multicast, the service latency is essentially zero. Furthermore, since most services require the server to deliver only a small leading portion of the video, the server can serve many more clients per time unit. We analyze the performance of this approach, and determine the optimal condition for when to use this strategy. We compare its performance to a hardware solution called Piggybacking. The results indicate that more than 200% improvement is achievable.