A Consistency Management Layer for Inter-Domain Routing

This paper proposes an isolation layer – a shim – between inter-domain routing and packet forwarding. The job of this layer is to coordinate between Autonomous Systems (AS’s) on when and how to modify the forwarding state to ensure interdomain routing loops do not cause forwarding loops. The benefits of a consistency layer are twofold. First, it prevents the creation of transient inter-domain forwarding loops and the resulting packet loss, high latency, and connection failures. Second, by taking the burden of forwarding consistency off the interdomain routing protocol, it enables inter-domain routing protocols with more complex convergence characteristics than BGP, such as protocols that optimize route selection based on performance. We offer two possible designs for the consistency layer. We prove that both designs are free of forwarding loops and show they are easy to deploy in the current Internet.