A Path - Finding Algorithm for Loop - Free

| A loop-free path-nding algorithm (LPA) is presented ; this is the rst routing algorithm that eliminates the formation of temporary routing loops without the need for internodal synchronization spanning multiple hops or the speciication of complete or variable-size path information. Like other previous algorithms, LPA operates by specifying the second-to-last hop and distance to each destination; this feature is used to ensure termination. In addition, LPA uses an inter-neighbor synchronization mechanism to eliminate temporary routing loops. A detailed proof of LPA's correctness and loop-freedom property is presented and its complexity is evaluated. LPA's average performance is compared by simulation with the performance of algorithms representative of the state of the art in distributed routing, namely an ideal link-state (ILS) algorithm, a loop-free algorithm that is based on internodal coordination spanning multiple hops (DUAL) and a path-nding algorithm without the inter-neighbor synchronization mechanism. The simulation results show that LPA is a more scalable alternative than DUAL and ILS in terms of the average number of steps, messages, and operations needed for each algorithm to converge after a topology change.