OpenFlow is a communications protocol that gives access to the forwarding plane of anetwork switch or router over the network. In simpler terms, OpenFlow allows the path of network packets through the network of switches to be determined by software running on a separate server. This separation of the control from the forwarding allows for more sophisticated traffic management than what is feasible using access control lists (ACL)s and routing protocols. Its inventors consider OpenFlow an enabler of "Software Defined Networking".
OpenFlow has been implemented by a number of network switch and router vendors including Brocade Communications, Arista Networks, Cisco, Extreme Networks, IBM,Juniper Networks, Hewlett-Packard, and NEC. Some network control planeimplementations use the protocol to manage the network forwarding elements. OpenFlow is mainly used between the switch and controller on a secure channel.
Indiana University in May 2011 launched the SDN Interoperability Lab in conjunction with the Open Networking Foundation to test how well different vendors' Software-Defined Networking and OpenFlow products work together.
In February 2012 HP said it is taking its first leap into OpenFlow-enabled network equipment, supporting the standard on 16 of its Ethernet switch products as it attempts to gain a foothold in a market likely to receive significant attention.