Multicast protocol implementation and validation in an ad hoc network testbed

We present our experiences in implementing and validating the on-demand multicast routing protocol (ODMRP) in a real wireless ad hoc network testbed. ODMRP maintains a mesh for each multicast group to provide multiple alternate paths. Redundancy created by the mesh helps overcome frequent topology changes resulting from node mobility, channel fading, and interferences. The protocol does not maintain permanent route tables with full topological views. Instead, multicast senders reactively and dynamically discover routes and obtain multicast group information on demand. ODMRP is implemented in our testbed network consisting of six hosts using the kernel level multicast support option built into the Linux operating system. We describe the key design and implementation features of our protocol and report preliminary testbed experiment results of ODMRP and DVMRP (distance vector multicast routing protocol), a traditional tree based scheme.