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.
An OpenFlow controller simply defines how frames are forwarded through the network, and the controller has an end-to-end view. It can potentially make more intelligent decisions based on the goals you want to achieve and the capabilities of the switch hardware, and can respond to changes in demand.
Not all applications are created equal. We already showed how VoIP traffic can maintain its SLA requirements, even under congestion, by dynamically moving lower-priority traffic to other paths. Similarly, you can define multiple paths with varying priorities so that if a primary path fails, a secondary path can be selected immediately with a lower failover time than with traditional L2/L3 methods.
Since the OpenFlow controller controls the network, it becomes the integration point for anything network-related, such as hypervisors, applications, security functions and load balancing. Integration moves from individual switches to the controller.