Pre-emptive Dynamic Source Routing: A Repaired Backup Approach and Stability Based DSR with Multiple Routes

Abstract

DSR algorithm finds out the best path for communicating between two nodes in a highly dynamic environment. Since, the environment changes frequently, the probability of established path breakage is also high. Again, as the breakage possibility increases, a new route has to be discovered every time .In order to avoid path discovery every time, we propose the modification of the existing DSR algorithm. In this paper we propose an enhancement of the DSR protocol based on a backup route(second best route) which will be provided by the destination node to the source node along with the best route during the process of path discovery. During the path maintenance process, in case any intermediate node identifies that the signal strength falls below a threshold i.e. the established route is about to break, the intermediate node sends a caution message to the source node. The source node switches the communication through the backup path , apprehending that the established route is about to break. As the communication through the backup route takes place, the previous route is repaired, if possible and acts as the new backup route. This process of toggling between backup route and established route reduces the call for path discovery to some extent. The stability in consideration of failure of common link and nodes in the back up repaired algorithm has been investigated with new algorithm for stable route selection.