Shared tree wireless network multicast

In this paper we propose a multicast protocol for a multihop, mobile wireless network with cluster based routing and token access protocol within each cluster. The multicast protocol uses a shared tree which is dynamically updated to adjust to changes in topology and membership (i.e. dynamic joins and quits). Two options for tree maintenance have been simulated and evaluated: "hard state" (i.e. each connection must be explicitly cleared) and "soft state" (each connection is automatically timed out and must be refreshed). For the soft state policy, the performance of different choices of timeout and refresh timers is first analyzed for a range of node mobility values. Next, soft state and hard state policies are compared based on throughput, join delay, and control overhead criteria.