Significance of Controller in Software Defined Networks

The Software Defined Networks (SDN) provides an innovative paradigm for networking, which improve the programmability and flexibility of the network. Due to the separation between the control and data plane, all the control logic transfer to the controller. Thus, the controller provides a centralized logical view of the entire network. Therefore, all manipulation and implementation in the network are control by a single controller in the SDN, which increases the maximum chance of a central point of failure in the network. As a consequence, it collapses the entire network. Therefore, a fault tolerance mechanism is required which reduces SPOF in the network by using multiple controllers. As a significance, the multiple controllers increase the scalability, reliability, and high availability of services in the network. The various roles of multiple controllers are Equal, Master and Slave exist in the Software Defined Networks. During the simulation to analyse, when a SPOF is happening in SDN then the value of the packet loss parameter is increasing gradually till the controller becomes again in the working condition. Thus, to resolve this problem by using multiple controllers in the networks.