Authors: Eman Ramadan (Ph.D. student), Hesham Mekky (Ph.D. 2016), Cheng Jin (Ph.D. 2018), Braulio Dumba (Ph.D. 2018), Zhi-Li Zhang (professor)
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 su!cient; resilient routing mechanisms that can e"ectively take advantage of such topological diversity also play a critical role. In this paper, we present Taproot, a resilient diversity routing algorithm that ensures bounded latency for packet delivery under failures by leveraging a preorder routing structure with precomputed routing rules. Leveraging the centralized control plane and programmable match-action rules 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 di"erent path avoiding failed links/nodes. Hence, the control channel is maintained without interruption, or involvement from the controller, and the throughput was not a"ected.