A Brief Introduction To OpenFlow, November 14, 2011 OpenFlow is a specification now managed by the Open Networking Foundation, which defines the functions and protocols used to centrally manage switches via a centralized controller.
The switch as position 1 is added to the network and configured with the credentials and address for the controller. It contacts the controller, which queries the switch for its capabilities and configuration. Then the controller pushes any configuration it has to the switch. The controller updates its view of the network and forwarding policies and updates the existing switches forwarding tables if necessary, making the new switch available to carry traffic.