A Caching Scheme for Routing in Mobile Ad Hoc Networks and Its Application to ZRP

A large class of routing protocols for MANETs, namely, reactive protocols, employ some form of caching to reduce the number of route discoveries. The simplest form of caching is based on associating a timeout with each cache entry. Such timer-based cache schemes can increase the protocol efficiency. However, if the timeout is not well-tuned, a severe performance degradation arises as entries are removed either too early or too late from the cache. In this paper, we address the problem of designing a proactive cache scheme that does not rely on any timer-based mechanism. This scheme guarantees that valid cached routes are never removed while stale routes are removed aggressively. This proactive cache scheme has been embedded in the Zone Routing Protocol (ZRP) framework and evaluated by an extensive simulation study.