Demystifying Failure Recovery for Software-Defined Wireless Mesh Networks

Software Defined Networking (SDN) brings unprecedented opportunities for facilitating the management of Wireless Mesh Networks (WMNs), particularly when handling network dynamics such as link/node failures. The inflexible destination based routing and failure recovery of conventional WMN routing protocols are superseded by the efficient and highly flexible per flow (re)routing in SDN-based networks. Most of the existing works focus on protection by pre-computing backup paths using OpenFlow fast failover groups to reroute the flows in case of channel re-assignment or a single link failure in software defined WMNs. However, the limitations of failure detection using link monitoring for protection have not been studied. Moreover, the potentials of restoration-based failure recovery to handle single/multiple failure scenarios, have not been fully investigated. In this paper, we implement a prototype for reactive failure recovery in multi-radio multi-channel software-defined WMNs that provides a detailed performance and sensitivity analysis. The acquired results from the SDN-based scenarios outperform the most popular conventional WMN routing protocols in terms of recovery time while preserving the best achievable throughput even when the out-of-band control network is partially impaired. We also demonstrate the limitation of link monitoring, which mainly results from the shared nature of wireless medium, for protection-based mechanisms in software-defined WMNs.