Software defined wireless sensors network fault tolerance framework
Mathebula, Risimati Ishmael
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Software-Defined Networking (SDN) is a new network paradigm that supports the decoupling of the control plane and the data plane where the controller is the central intelligence or the brain of the entire network. SDN has attracted widespread application due to its flexibility in networks management and control. SDN has also been adopted in several existing network technologies and wireless sensors network (WSN) is not an exception resulting to SDWSN. At the moments the SDWSN controller is only single and lacks fault tolerance (FT) capability. As the brain of the network, it is prone to several faults, errors, security attacks, and poses as a single point of failure of the network. Therefore, to ensure the single point of failure is eliminated in the SDWSN controller, this research proposed a FT framework in the SDWSN control plane that ensures continuous reliability and availability of the SDWSN controller's execution. This is achieved by designing a FT framework which is made of two core components: the 3-phase or the EDD controllers and the FT Manager (FTM). On the 3-phase controllers, only one controller is responsible for network management while the other two remain as standby during the event of failure. Moreover, FTM also monitors the executing controller using heartbeat techniques to detect the occurrence of fault or failure. The FTM is made of five managers: heartbeat, execution, checkpoint, diagnostic and voting. The managers operate cooperatively to ensure the reliability, availability, state consistency and better performance of the SDWSN controller. We also present the design of each component, its operation and discussion. In addition, simulations and theoretical evaluations were performed on the FT framework as proof of concept. The simulations utilized the OpenDayLight (ODL) controllers and the Mininet software tool while the theoretical evaluations were carried out based on several criteria and parameters. The results obtained from the simulation show that the SDWSN controller is indeed the brain of the entire network and is capable of providing an abstract or global view of the entire network. In terms of the theoretical evaluation, it shows that FT framework is standardized and is effective in ensuring the controller's reliable execution in the detection and recovery from faults or failures in the network. The results show that our FT framework can offer effective fault detection and fault recovery to ensure the SDWSN controller remains operational in the face of faults or failure in the network. Moreover, if the FT framework is adopted for implementation in the real-world SDWSN, it could go a long way to eliminate the single point of failure posed by a single controller in OpenFlow architecture.