In this talk, we expand on our earlier NANOG presentation with an exploration of what roles inter-domain topology and routing policy play in the process of delayed Internet routing convergence. In our previous talk, we demonstrated that the Internet lacks effective inter-domain path fail-over with backbone routers requiring tens of minutes to reach a consistent view of the network topology after a fault. We also presented a theoretic, upper factorial bound on BGP convergence computation.

Based on analysis from the experimental injection and measurement of several hundred thousand additional inter-domain routing faults, this talk provides a tighter, more realistic/expected bound on BGP convergence. We describe how specific routing policies and Internet topologies impact the time for convergence. Finally, we describe and provide probable explanations for significant measured variations in the convergence behaviors of different Internet service providers.