Probabilistic Reliable Multicast in Ad Hoc Networks

When striving for reliability, multicast protocols are most commonly designed as deterministic solutions. Such an approach seems to make the reasoning about reliability guarantees (traditionally binary "all-or-nothing"- like) in the face of packet losses and/or node crashes. It is however precisely this determinism that tends to become a limiting factor when aiming at both reliability and scalability, particularly in highly dynamic networks, e.g., ad hoc networks. Gossip-based multicast protocols appear to be a viable path towards providing multicast reliability guarantees. Such protocols embrace the non-deterministic nature of ad hoc networks, providing analytically predictable probabilistic reliability guarantees at a reasonable overhead. This paper presents the Route Driven Gossip (RDG) protocol, a gossip-based multicast protocol designed precisely to meet a more practical specification of probabilistic reliability in ad hoc networks. Our RDG protoool can be deployed on any basic on-demand routing protocol, achieving a high level of reliability without relying on any inherent multicast primitive. We illustrate our RDG protocol by layering it on top of the ¡°bare¡± DSR protocol, and convey our claims of reliability and scalability through both analysis and simulation.