Optimal Recovery from Large-Scale Failures in IP Networks Qiang Zheng, Guohong Cao, Tom La Porta, and Ananthram Swami

1. Large-scale failures in IP networks • Routers and links within an area all fail. • A large number of routing paths are disconnected. • Many events can cause large-scale failures. • Natural disasters: hurricane, earthquake, and flood • Intentional attacks: weapons of mass destruction and terroristic events • Existing recovery approaches cannot effectively deal with large-scale failures • Accelerating the routing protocol convergence may make networks more unstable. • Links and their backup paths may fail simultaneously. Optimal Recovery from Large-Scale Failures in IP NetworksQiang Zheng, Guohong Cao, Tom La Porta, and Ananthram Swami • Two major challenges • The failure area can be of any shape and at any place. • No individual router has the overall information of failures. RTR: Reactive Two-phase Rerouting Performance Evaluation • Overview • Phase 1: collects failure information, i.e., identifying which links have failed. • Phase 2: calculates a new shortest path and uses source routing to forward packets along it. Duration of phase 1 Introduction • Length of recovery paths • Stretch: recovery path length / length of the shortest path • Phase 1: collecting failure information • Forwards packets around the failure area with the following rules • Records the ids of failed links in the packet header Computational overhead • Phase 2: recomputing and rerouting • Recomputes the shortest path to reach the destination based on the failure information collected in phase 1. • Forwards packets along the shortest path through source routing This work was supported in part by the Defense Threat Reduction Agency under grant HDTRA1-10-1-0085.