IMPLEMENTATION OF RETRANSMISSION SCOPING IN MULTICAST SYSTEM

Abstract

Many emerging Internet applications are one-to-many or many-to-many, where one or multiple sources are sending to multiple receivers. Multicasting provides an efficient way of disseminating data from a sender to a group of receivers. Multicasting is a very broad term and different multicasting applications have different requirements. Applications that support video and voice do not require reliable data transfer, while applications such as shared whiteboards, distributed interactive simulations, multicast file transfer, stock quote dissemination, web cache updates etc. do. To ensure reliability, the sender must retransmit .a lost packet. Retransmissions of packets are done on a separate multicast channel, which receivers dynamically join and leave. This is due to the fact that receivers do not receive re-transmissions of packets they have already received correctly. Firstly it has been assumed that there are infinite numbers of multicast channels. Later on, it has been shown that very few numbers of multicast channels are required to achieve most of the benefit of using an infinite number of multicast channels. Next, the number of unwanted redundant packets at a receiver due to using only a finite number of multicast channels, for NAK based protocol has been calculated. The minimum number of multicast channels required to keep the cost of processing unwanted packet to a sufficiently low value has been explored.