Taproot: Resilient Diversity Routing with Bounded Latency

Abstract

As we increasingly depend on networked services, ensuring resiliency of networks against network failures and providing bounded latency to applications become imperative. Adding ample redundancy in the network substrate alone is not sufficient; resilient routing mechanisms that can effectively take advantage of such topological diversity also play a critical role. In this paper, we present Taproot, a resilient diversity routing algorithmthat ensures bounded latencyfor packet delivery under failures by leveraging a preordeR@routing structure with precomputed routing rules. Leveraging the centralizedcontrol plane and programmable match-actionrules in the data plane, we describe how Taproot can be realized in SDN networks. We implement Taproot in OVS and conduct extensive simulations and experiments to demonstrate its superior performance over existing solutions. Our results show that by tuning the latency allowance upon failure, Taproot reduces/eliminates the number of disconnected src-dst pairs even under 10 link failures. Finally, as a use case, we illustrate the impact of control channel failures on SDN data plane/application performance, and employ Taproot to provide a "hardened" SDN control network with bounded latency against failures. Our results show that Taproot immediately detects the failure and re-routes the control messages to a different path avoiding failed links/nodes. Hence, the control channel is maintained without interruption, or involvement from the controller, and the throughput was not affected.