Software Defined Networks (SDN) is the qualitative movement in the field of networks due to that fact that it separates the control elements from the routing elements, and the function of the routing elements was limited to the implementation of the
decisions that are sent to it by the controller through the OpenFlow Protocol (OF) which is mainly used in SDN. We explain in this paper the benefit of the new concept which is presented by SDN and it makes network management easier, so instead of writing the rules on each device, we program the application in the controller, and the infrastructure devices run the received commands from the controller. In order to achieve the best performance of this technology, a Quality of Service (QoS) must be applied within it, where it includes several criteria, the most important are the used bandwidth, delay, packet loss and jitter. The most important of these criteria is the bandwidth, because by improving this standard, we can improve the rest of the other criteria. Therefore, in this paper, we provide the necessary improvement on the RYUcontroller to use the best bandwidth, which improves the quality of service in SDN.
Current traditional IP networks start to be complex as the demands of the users are ever-growing. Software Defined Network (SDN) is a new paradigm to ease the management of the network and make the network programmable by decoupling the control plane
and forwarding plane (such as switch and router). A centralized controller is used to manage the control plane, and it interacts with the forwarding plane using a standardized OpenFlow protocol. However, many controllers are used recently such as POX, Ryu, ONOS, and OpenDaylight. The important question is which is the best controller to use in our network and fits our network’s goals? To answer this question, a decision-making method is proposed in this paper. First, four SDN controllers are selected, and five criteria are analyzed to collect these controllers’ properties. Then a Multi-Criteria Decision Making method named TOPSIS is used to rank the controllers and choose the best one. By applying this method, a comparative study is done to evaluate the four controllers in an environment of LAN topology, and “Ryu” controller is selected as the best one based on our criteria.
