WAIT, selective loss recovery for multimedia multicast

by Mane, Pravin D.

Recently the Internet has been increasingly used for multi-party applications like video-conferencing, video-on-demand and shared white-boards. Multicast extensions to IP to support multi-party applications are best effort, often resulting in packet loss within the network. Since some multicast applications can not tolerate packet loss, most of the existing reliable multicast schemes recover each and every lost packet. However, multimedia applications can tolerate a certain amount of packet loss and are sensitive to long recovery delays. We propose a new loss recovery technique that selectively repairs lost packets based upon the amount of packet loss and delay expected for the repair. Our technique sends a special WAIT message down the multicast tree in the event a loss is detected in order to reduce the number of retransmission requests. We also propose an efficient sender initiated multicast trace-route mechanism for determining the multicast topology and a mechanism to deliver the topology information to the multicast session participants. We evaluate our proposed technique using an event driven network simulator, comparing it with two popular reliable multicast protocols, SRM and PGM. We conclude that our proposed WAIT protocol can reduce the overhead on a multicast session as well as improve the average end-to-end latency of the session. I dedicate this thesis to my wonderful family without whose love and support I would not have been who I am today. The family I love the most... the MANE family... “ The most exciting phrase to hear in science, the one that heralds new discoveries, is not “Eureka!” (“I found it!”) but rather “hmm....that’s funny...” –Isaac Asimov. “ If a man will begin with certainties, he will end in doubts; but if he will be content to begin with doubts, he will end in certainties.” -Francis Bacon (1561-1626) “ May every young scientist remember and not fail to keep his eyes open for the possibility that an irritating failure of his apparatus to give consistent results may once or twice in a lifetime conceal an important discovery.” - Patrick Blackett (British physicist, 1897-1974) “ Keep on the lookout for novel ideas that others have used successfully. Your idea has to be original only in its adaptation to the problem you’re working on.” - Thomas Edison (1847-1931). “ Results! Why, man, I have gotten a lot of results. I know several thousand things that won’t work. ” - Thomas Edison (1847-1931).