Software Defined Networking (SDN) is a term coined by Kate Greene and refers to a network architecture in which the network control plane is decoupled from the physical topology. The rational for this approach is twofold. First, the decoupling allows for the control plane to be implemented using a different distribution model than the dataplane. Second, it allows the control plane development and runtime environment to be on a different platform than the traditionally low-powered management CPUs found on hardware switches.

SDN requires some method for the control plane to communicate with the switch datapath. One such mechanism is OpenFlow which is a standard interface for controlling computer network

Computer network

A computer network, often simply referred to as a network, is a collection of hardware components and computers interconnected by communication channels that allow sharing of resources and information....

ing switches. OpenFlow is often confused to be equivalent to SDN. However, there is no requirement for the use of OpenFlow within an SDN.

Definition and marketing of SDN and OpenFlow is managed by the Open Networking Foundation.