A Reliable, Efficient Topology Broadcast Protocol for Dynamic Networks

We present, prove correctness for, and evaluate a protocol for the reliable broadcast of topology and link-state information in a multihop communication network with a dynamic topology, such as a wireless network with mobile nodes. The protocol is called Topology Broadcast based on Reverse Path Forwarding (TBRPF), and uses the concept of reverse-path forwarding (RPF) to broadcast link-state updates in the reverse direction along the spanning tree formed by the minimum-hop paths from all nodes to the source of the update. TBRPF uses the topology information received along the broadcast trees to compute the minimum-hop paths that form the trees themselves, and is the first topology broadcast protocol based on RPF with this property. The use of minimum-hop trees instead of shortest-path trees (based on link costs) results in less frequent changes to the broadcast trees and therefore less communication cost to maintain the trees. Simulations show that TBRPF achieves up to a 98% reduction in communication cost compared to flooding in a 20-node network. Keywords— Topology broadcast, link-state routing, reverse-path forwarding, mobile network, packet-radio network.