An Analysis of Path-Vector Routing Protocol Convergence Algorithms

Today’s Internet uses a path vector routing protocol, BGP, for global routing. After a connectivity change, a path vector protocol tends to explore a potentially large number of alternative paths before converging on new stable paths. Several techniques for improving path vector convergence have been proposed, however there has been no comparative analysis to judge the relative merit of each approach. In this paper we develop a novel analytical framework for analyzing the convergence delay bounds of path-vector routing protocols in general. Our framework can accommodate different message processing delay models. By incorporating the commonly used uniform processing delay model we are able to fill in all the cases where analytical results are missing previously. The results obtained by using our framework not only confirm the previous work but also provide new insights into the underlying network behavior. We then present a new delay model, the model, which takes into account the actual message queueing delay in actual BGP implementations and simulations. By incorporating the model in our framework, we are able to obtain tighter delay bounds and explain simulation results that cannot be explained using the previous uniform message delay model.