Using Multi-Topology Routing to improve routing during geographically correlated failures

During large geographic events in networks, the routing churn that occurs has been shown to cause significant impacts in routing stabilization following the event. This work proposes a set of algorithms that is based on Multi-Topology Routing (MTR) for pre-planning for geographically correlated failures. Thus, in the event of a failure, our approach, Geographic MTR, switches to virtual topologies that reduce the impact of routing changes that can result in dropped connections until a new link state and shortest path trees can be established. We propose two algorithms to generate virtual topologies, Geographic Coverage MTR (gcMTR) and Geographic Targeted MTR (gtMTR). The first method, gcMTR, is to create virtual topologies taking a network wide coverage approach, while gtMTR is a targeted approach that can be used in anticipation of a specific event where knowledge of that event exists. A third algorithm proposed in this work specifies a way to detect a geographic event and select a topology to use. We evaluated our approach on two network topologies and observed that the number of connections that are dropped during a geographic event can be reduced significantly, thereby reducing the impact to the non-affected part of the network.