WHAT IS OPENFLOW?

OpenFlow is the first standard communications interface defined between the control and forwarding layers of an SDN architecture. OpenFlow allows direct access to and manipulation of the forwarding plane of network devices such as switches and routers, both physical and virtual (hypervisor-based).

OpenFlow-based SDN technologies enable IT to address the high-bandwidth, dynamic nature of today's applications, adapt the network to ever-changing business needs, and significantly reduce operations and management complexity.


The fundamental innovation of OpenFlow is defining the communication protocol in an SDN environment that enables the SDN controller to interact with the forwarding plane of network devices such as switches and routers, both physical and virtual (hypervisor-based), so it can better adapt to changing business requirements. Technically, this is described as the separation of the control from the data forwarding plane – but a more important way to think about it is the creation of a more flexible switching architecture that abstracts control to software. 
These innovations mean that functions that were previously captive to a number of proprietary routing and switching networking products can now be enabled as software only and are no longer captive to a proprietary system. One goal of the SDN movement was to have a collection of standardized hardware boxes that could be operated by separate software control, offering more flexibility and interoperability.


The Open Networking Foundation (ONF) is an organization dedicated to promotion and adoption of software-defined networking (SDN) and manages the OpenFlow standard. ONF defines OpenFlow as the first standard communications interface defined between the control and forwarding layers of an SDN architecture. OpenFlow allows handling of the forwarding plane of network devices such as switches and routers, both physical and virtual (hypervisor-based). It is the absence of an open interface to the forwarding plane/data plane that has led to the characterization of today's networking devices as monolithic, closed, and mainframe-like. A protocol like OpenFlow is needed to move network control out of proprietary network switches and into control software that's open source and locally managed.

A number of network switch and router vendors have announced intent to support are shipping supported switches for OpenFlow, including Alcatel-Lucent, Big Switch Networks, Brocade Communications, Radisys, Arista Networks, Huawei, Cisco, Dell Force10, Extreme Networks, IBM, Juniper Networks, Hewlett-Packard. Some network control plane implementations use the protocol to manage the network forwarding elements.OpenFlow is mainly used between the switch and controller on a secure channel.

Version 1.1 of the OpenFlow protocol was released on 28 February 2011, and new development of the standard was managed by the Open Networking Foundation (ONF). In December 2011, the ONF board approved OpenFlow version 1.2 and published it in February 2012. The current version of OpenFlow is 1.4.