An Energy Efficient SDN Controller Placement with Delay Constraints

Software-Defined Networking (SDN) separates the control from the data plane in the network infrastructure to flexibly and efficiently manage the resources. Since the controller is the core of the control plane, multiple instances need to be placed within the network to increase performance, reliability, and fault tolerance, among others. However, deciding the number and where to place the allotted controllers is not trivial; it is known as the Controller Placement Problem (CPP). This paper considers the energy-efficiency aspect of the network infrastructure to solve the CPP. To do so, we designed a model that includes delay constraints, whose effectivity was assessed and confirmed to save about 20-30% more energy than a model that only considers the number of controllers. Moreover, it is confirmed that execution time can be decreased by 100 times while keeping the energy consumption low by reducing the number of pre-calculated paths between the SDN switches and the controllers.