Reliable broadcast in mobile multihop packet networks

Abstract

We describe a reliable broadcast protocol for mobile multi-hop packet radio networks. The reliable broadcast service ensures that all the hosts in a group deliver the same set of messages to the upper layer. It represents the building block to construct fault tolerant distributed applications, whose demand is growing in a mobile environment too. The protocol is intended for use in networks where the host mobility arbitrarily changes the network connectivity and where the rate of change is not so fast as to impose flooding as the only option. In this context, our protocol is a first attempt to show that a mechanism more flexible than spanning tree and more efficient than flooding is possible and a service such as the reliable broadcast can be obtained. The protocol is constructed on top of a multi-hop, multi-cluster architecture. It provides an exactly once message delivery semantics and tolerates communication failures and host mobility. Temporaneous disconnections and network partitions are also tolerated under the assumption that they are eventually repaired.