Tunnel Vector: A New Routing Algorithm with Scalability


Routing algorithms such as Distance Vector and Link States have the routing table size as O(n), where n is the number of destination identifiers, thus providing only limited scalability for large networks when n is high. As the distributed hash table (DHT) techniques are extraordinarily scalable with n, our work aims at adapting a DHT approach to the design of a network-layer routing algorithm so that the average routing table size can be significantly reduced to O(log n) without losing much routing efficiency. Nonetheless, this scheme requires a major breakthrough to address some fundamental challenges. Specifically, unlike a DHT, a network-layer routing algorithm must (1) exchange its control messages without an underlying network, (2) handle link insertion/deletion and link-cost updates, and (3) provide routing efficiency. Thus, we are motivated to propose a new network-layer routing algorithm, Tunnel Vector (TV), using DHT-like multilevel routing without an underlying network. TV exchanges its control messages only via physical links and is self-configurable in response to linkage updates. In TV, the routing path of a packet is near optimal while the routing table size is O(log n) per node, with high probability. Thus, TV is suitable for routing in a very large network.