Non-Real Time Reliable Multicast Protocol Using Sub Sub-Casting

In this paper, a Reliable Multicast transport protocol over combined (fixed/mobile) networks using Sub Sub-casting called (RMSS) is proposed. RMSS is based on a hierarchical structure where receivers are grouped into local regions. In each local region there are special receivers, which are called Designated Receivers (DRs) and Mobile Agents (MAs). Each DR or MA is responsible for retransmission of requested packets to the receivers which belong to its local region. DRs and MAs send their acknowledgments periodically to the sender. They also process the acknowledgments sent to them from the Fixed Hosts (FHs) and Mobile Hosts (MHs) and they retransmit lost packets to the requesting receivers. A sub sub-casting technique is applied within these relatively smaller regions, where the repaired packets are retransmitted only to the requested receivers of the local group. These receivers form a sub group of the local group which itself is a subgroup of the global multicast group. By applying sub sub-casting technique the number of duplicated packets due to retransmission of packets drops to zero which improves the system performance. Simulations (using C++) have demonstrated the scalability of RMSS with sub sub-casting technique.