Scalable Landmark Routing and Address Lookup for Multi-hop Wireless Networks

This paper proposes and analyzes modifications to the Landmark routing system that make it better suited to large ad hoc wireless networks. Most existing ad hoc routing algorithms scale badly in the sense that they generate protocol overhead whose per-node cost grows linearly with the total number of nodes. The Landmark routing protocol solves this problem by use of hierarchical addresses that contain routing hints; as a result, however, a node’s address changes as the network topology changes. The Landmark system tracks node addresses with a distributed ID-to-address location service, but queries to this service require communication with random non-local nodes, which scales badly in large networks. The main contribution of this paper is a set of modifications to the Landmark address lookup service to make it more scalable. The paper also improves the Landmark hierarchy maintenance and routing algorithms to help them react better to mobile nodes. Finally, it presents a simulation evaluation of the resulting system, L, from the point of view of scalability in wireless ad hoc networks. The evaluation shows that the per-node bandwidth requirement of L grows very slowly as the number of nodes in the network increases. This is consistent with our analysis that the per-node communication cost of L is O(log N).