OpenFlow
OpenFlow is a protocol standardized by the Open Networking Foundation( ONF) that offers high flexibility for network virtualization. OpenFlow is implemented as an additional feature in Ethernet switches, routers, and wireless access points( WAP) and provides the ability to run other protocols on these networks without knowing details of the network components. OpenFlow is an approach for Software Defined Networking( SDN) and is implemented by well-known manufacturers in their components.
Unlike classic routers or switches, which operate with a data path for forwarding data packets and a control path for routing decisions, OpenFlow separates these two functions.
The data path function remains in the switch, while the routing decision is outsourced to a separate controller, the OpenFlow controller. With OpenFlow, routing tables are managed centrally in the OpenFlow controller, allowing the network to be segmented and virtualized and traffic to be controlled. Switches with implemented OpenFlow software communicate with the OpenFlow controller using defined control commands such as: Receive data packet or Modify routing table. Routes across the network are determined by flows, which are determined by the flow data sent out by the routers and switches. The OpenFlow controllers thus have an overview of the network, supporting dynamic provisioning.