Fast Reroute in Hybrid Segment Routing Network

Abstract

We consider a hybrid segment routing (SR) network consisting of both IP routers and SR routers. We focus on exploiting the source routing capability of SR to enhance the performance of IP fast reroute. In particular, an IP router detects a local link failure, it can immediately reroute the affected packets by tunneling them to a SR router. The SR router will then forward the rerouted packets along a SR path such that when they exit the SR domain, they can reach the destination without traversing the failed link. In order to maximize the percentage of links that can be protected by fast reroute, two Integer Linear Programming (ILP) formulations are proposed for finding optimal repair paths for rerouted packets. ILP1 aims at minimizing the repair path length and ILP2 focuses on balancing the traffic load in the network. We further show that as the number of SR routers increases, the average repair path length will be shortened and the load balancing performance will be improved.