On software-defined networking and the design of SDN controllers

Software-Defined Networking (SDN) has emerged as a networking paradigm that can remove the limitations of current network infrastructures by separating the control plane from the data forwarding plane. The implications include: the underlying network state and decision making capability are centralized; programmability is provided on the control plane; the operation at the forwarding plane is simplified; and the underlying network infrastructure is abstracted and presented to the applications. This paper discusses and exposes the details of the design of a common SDN controller based on our study of many controllers. The emphasis is on interfaces as they are essential for evolving the scope of SDN in supporting applications with different network resources requirements. In particular, the paper review and compare the design of the three controllers: Beacon, OpenDaylight, and Open Networking Operation System.