A path-finding algorithm for loop-free routing

Abstract

A loop-free path-finding algorithm (LPA) is presented; this is the first routing algorithm that eliminates the formation of temporary routing loops without the need for internodal synchronization spanning multiple hops of the specification of complete or variable-size path information. Like other previous algorithms, the LPA operates by specifying the second-to-last hop and distance to each destination; this feature is used to ensure termination. In addition, the LPA uses an interneighbor synchronization mechanism to eliminate temporary routing loops. A detailed proof of the LPAs correctness and loop-freedom property is presented and its complexity is evaluated. The LPAs 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-finding algorithm without the interneighbor synchronization mechanism. The simulation results show that the 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.