Performance of route caching strategies in Dynamic Source Routing

On-demand routing protocols for mobile ad hoc networks utilize route caching in different forms in order to reduce the routing overheads as well as to improve the route discovery latency. For route caches to be effective, they need to adapt to frequent topology changes. Using an on-demand protocol called Dynamic Source Routing (DSR), we study the problem of keeping the caches up-to-date in dynamic ad hoc networks. Previous studies have shown that cache staleness in DSR can significantly degrade performance. We present and evaluate three techniques to improve cache correctness in DSR namely wider error notification, route expiry mechanism with adaptive timeout selection and the use of negative caches. Simulation results show that the combination of the proposed techniques not only result in substantial improvement of both application and cache performance but also reduce the overheads.