Routing for Data Delivery in Dynamic Networks

In this paper, we present a routing algorithm for a class of dynamic networks called the delay tolerant networks (DTNs). The proposed algorithm takes into account the quintessential DTN characteristic namely, intermittent link connectivity. Assuming a store and forward type of network transfers, our main objective in designing routing algorithms for such an environment is to maximize the number of delivered messages subject to storage constraints on intermediate nodes. We modify the simple breadth first search (BFS) algorithm to take into account link activation/deactivation and find the quickest route possible between source and destination nodes. We adopt a message drop policy at intermediate nodes to incorporate storage constraint into data delivery. We also introduce the idea of storage domain where a few connected nodes act as a single storage unit by sharing the aggregated storage capacity of the nodes in the domain. We evaluate the routing algorithm with and without storage domain in an extensive simulation for two types of network topologies-flat and layered. We implement the proposed routing algorithm in ns2 and present an extensive performance analysis using metrics such as delivery ratio, incomplete transfers with no routes and dropped messages. The most significant simulation result shows that routing with storage domain mitigates the storage bottleneck at a gateway node for a layered network topology. For instance, the delivery ratio for storage capacity of 10 with storage domain surpasses the delivery ratio for storage capacity of 20 without storage domain