Improvement of link cache performance in Dynamic Source Routing (DSR) protocol by using active packets

Dynamic Source Routing (DSR) is an efficient on-demand routing protocol for ad hoc networks, in which only needed routes are found and maintained. The route discovery/setup phase becomes the dominant factor for applications with short-lived small transfer traffic (one single packet or a short stream of packets per transaction) between the source and the destination: resource discovery, text-messaging, object storage/retrieval, queries and short transactions. Route caching is helpful to avoid the need for discovering a route or to shorten route discovery delay before each data packet is sent. The goal of this work is to develop a caching strategy that permits nodes to update their cache quickly to minimize end-to-end delay for short-lived traffic. The proposed approach consists of an Active Packet that travels through the nodes of the network twice. During the first travel, it visits the nodes collecting fresh network topology information. When the first visit is finished, another one is started to validate and update the caches of the nodes with this newly obtained information. This mechanism removes invalid cache links and caches valid links based on the collected topology information. The correct information in caches allows to speed up the Route Discovery and even to avoid it.