Speculative Route Invalidation to Improve BGP Convergence Delay under Large-Scale Failures

The border gateway protocol (BGP) has been known to suffer from large convergence delays after failures. We have also found that the impact of a failure rises sharply with the size of the failure. In this paper we present and evaluate a speculative route invalidation scheme aimed at reducing the convergence delays for large-scale failures. Our scheme collects statistics from BGP updates received at a router and identifies Autonomous Systems (ASes) that are likely to be "unstable". Routes that contain these ASes are marked as invalid and not propagated further. This cuts down the number of invalid routes during the convergence process and results in a significant improvement in the convergence delay.