An Empirical Characterization of Anycast Convergence Time

BGP convergence time is an important aspect of Internet operations and research alike. As an example, traffic steering during DDoS attacks necessitates swift topological changes. Problems surrounding delayed convergence are widely documented. However, little is known about real-world convergence times, especially in an anycast setting. This leads many BGP measurement studies to coarsely estimate the convergence time. In this work, we study BGP convergence using a global anycast testbed. The methodology we present combines two probing methods to measure routing stability from an end-user perspective. We find that 80% of the Internet converges within approximately 10 seconds but also that there is a long tail of networks that are slow to update.