On the internet grouping for reliable multicasting

Abstract

Current implementation of multicasting is using UDP protocol which is unreliable. There are many problems in reliable multicasting that make it difficult to implement. A study of the problems of reliable multicasting and an algorithm for reliable multicast protocol are proposed in this thesis. Unfairness when some of the receivers are faster than the others, the overhead at the sender because of managing all the group members and the problem of the traffic congestion at the sender because of the acknowledgments from each receiver are the problems that our proposed algorithm solved. Our proposed protocol is to divide the multicast group into different subgroups in a way that all members of the subgroup are related in speeds, location etc. In this way, we will make the sender send the same message with different speeds to different receiver subgroups. The sender will send as many times as the number of the subgroups. This solution has the advantage that fast receivers will not wait for slow receivers until they receive their message, which will improve the performance of fast receivers. To reduce the number of acknowledgments at the sender, we select from each subgroup a member that sends acknowledgment to the sender. In this way, only one acknowledgment from the subgroup is sent to the receiver rather than every member sending an acknowledgment to the sender, which solves the problem of many acknowledgments at the sender.