Hybrid Flow-Rule Placement Method of Proactive and Reactive in SDNs

In a software-defined network, the controller is an important element based on its effect on the entire network performance. The centralized controller property will lead to flexibility and reliability in network management; however, limitations in network resources such as switches’ limited flow table size and controller processing capacity may reduce network performance and increase controller response time. In this paper, we present a hybrid rule placement model for reducing the load on the controller. The proposed method solves the load problem by formulating the table size limitation and then combining the reactive and proactive methods in flow-rule placement algorithm. The main idea of this method is to make optimal use of switches’ limited flow table to reduce the signaling overhead on the controller, which leads to reduces the network reaction time to changes and the load on the controller. To achieve this goal, the proposed method prevents the sending of packets to the controller by installing Star rules on the switches. Finally, the proposed method implements and tests on a real network, and the results of simulation and evaluation of network performance have reduced the amount of load on the controller by 20 to 50%, which indicates the effectiveness of the proposed method.