Simulating convergence properties of BGP

We present a simple BGP simulator that is used for testing convergence properties of inter-domain routing. The discrete-event driven simulator contains a high-level abstraction model of the BGP protocol. The purpose is to perform simulations to examine the complexity of routing information exchange and to test different possible reasons for delayed convergence of BGP routing. We have simulated effects of BGP timers on convergence and compared the results with simulations done by Labovitz and Griffin. Our simulator displayed the theoretically predicted characteristics. We then tested the effects of skewed timers, split horizon and the sender side loop detection (SSLD) techniques on convergence for different network topologies. We conclude that SSLD helps to decrease the number of announcements and the convergence time. However, SSLD increases the number of withdrawals.