Improving the Resilience of Fast Failover Routing: TREE (Tree Routing to Extend Edge disjoint paths)

Abstract

Today's communication networks have stringent availability requirements and hence need to rapidly restore connectivity after failures. Modern networks thus implement various forms of fast reroute mechanisms in the data plane, to bridge the gap to slow global control plane convergence. State-of-the-art fast reroute commonly relies on disjoint route structures, to offer multiple independent paths to the destination. We propose to leverage the network's path diversity to extend edge disjoint path mechanisms to tree routing, in order to improve the performance of fast rerouting. We present two such tree-mechanisms in detail and show that they boost resilience by up to 12% and 25% respectively on real-world, synthetic, and data center topologies. Whereas the first method retains the stretch of edge disjoint path mechanisms, our second method increases it depending on the use case, just below 8% for networks from Topology Zoo on average, but by up to 56% for random graphs in the Erdős-Rényi model.