Cross-Layer Switch Handover in Software Defined Wireless Networks

Software-defined networking (SDN) is evolving to be one of the most important technologies for managing networks efficiently with minimum complexity. SDN achieves flexible routing by decoupling control and data planes. The control-plane populates forwarding devices with flow tables which contain actions to forward packets. OpenFlow is a standard protocol which enables the communication between the control-plane and the data-plane. Communications between a controller and a switch in Software-defined Wireless Networks are prone to failure. In this regard, a distributed control plane can be worth considering. In addition, since a controller possesses limited packet processing capabilities, we need to have an efficient solution for switch handover. In this work, we have studied the issues associated with OpenFlow wireless networks and have proposed a cross-layer hand over solution for efficient switch hand over. Our Cross-Layer OpenFlow Switch handover utilizes the RSSI of wireless links and the traffic load of Controllers for effective handover decision-making. We have further enhanced our cross-layer switch hand over with a soft hand over capability in order to avoid the packet drops due to hard hand over. We have developed a test-bed for OpenFlow Wireless networks for evaluating the performance of our hand over strategies. On an average, the packet drops observed were 10 and 8 during high traffic load and moderate traffic load, respectively, in Cross-Layer OpenFlow Switch handovers. Additionally, the soft handover extension eliminated the packet drops during switch handovers. The time taken for the switch handover is measured to be around 4.92 ms.