A Software-Defined Networking Approach for Disaster-Resilient WANs

The current technology of Internet provides an acceptable level of resilience in normal operation. However, the Internet may get catastrophic impacts when unexpected disasters such as earthquakes, tsunami, etc. happen. Specifically, the Internet infrastructure including Wide Area Networks (WANs) face many challenges to normal operation including power outage, link, device failures, rerouting packets, traffic engineering, etc. In this paper, we follow a systematic approach for realizing disaster-resilient WANs using Software-Defined Networking (SDN) technology. SDN enables the network control plane to be decoupled from the network forwarding hardware, and moves the control plane to a programmable component, i.e., the network controller. The network management and operation therefore increase flexibility. To confirm the feasibility of SDN-based resilient network towards fast disaster recovery, we have constructed two evaluations under the real large scale network topology. One is to investigate the latencies between controllers and switches in order to find the appropriate number and locations of controllers. Another one is to simulate a reactive switch-over from a faulty link to an alternative link, assuming a realistic scenario. The results show that the switch-over time depends on the latencies between networking devices and a controller. Additionally, even those latency values equal the worst-case latency, the fast rerouting of TCP traffic is achievable.