Scalable routing in delay tolerant networks

The non-existence of an end-to-end path poses a challenge inadapting the traditional routing algorithms to delay tolerantnetworks (DTNs). Previous works include centralized rout-ing approaches based on deterministic mobility, ferry-basedrouting with deterministic or semi-deterministic mobility, flooding-based approaches for networks with general mobility, and probability-based routing for semi-deterministicmobility models. Unfortunately, none of these methods canguarantee both scalability and delivery. In this work, we investigate scalable deterministic routing in DTNs. Instead of routing with global contact knowledge, we propose a simplified DTN model and a routing algorithm which routes on contact information compressed by three combined methods. Analytical studies and simulation results show that the performance of our proposed routing algorithm, DTN Hierarchical Routing (DHR), approximates that of the optimal time-space Dijkstra's algorithm in terms of delay and hop-count. At the same time, the per node storage overhead is substantially reduced and becomes scalable. Although our work is based on a simplified DTN model, we believe this approach will lay a groundwork for the understanding of scalable routing in DTNs.