Dynamic flow redirecton scheme for enhancing control plane robustness in SDN

In SDN, the controller is the core and is responsible for processing all flow requests of the network switches. However, due to the sudden occurrence and unbalanced distribution of flows in the network, it is likely that some controllers suffer workload that is far heavier than their load capacity, which leads to the failure of the controller and further leads to the paralysis of the entire network. To solve this problem, we propose a dynamic flow redirection scheme (DFR) to prevent network crash. We describe the phenomenon of controller failure caused by numerous flow requests. The flow redirection is formalized as a multi-objective optimization problem and constrained by flow table and bandwidth. We prove that the problem is NP-hard. We solve this problem with the dynamic flow redirection approach (DFR). First, state detection module detects whether the current flow requests will exceed the controller load. The Flow Redirection Assignment Module then computes the redirect path for the redundant flow request. Finally, Rule Dispense issues the flow rules to the corresponding switches. Simulation results show that DFR reduces network latency and reduces the overload probability of controllers by at least 3 times.