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Networking vendors, virtualization companies and social media giants like Facebook are developing switches to support software-defined networking. The protocol most frequently associated with software-defined networking (SDN) is OpenFlow, but other options may lure you elsewhere.
SDN puts switch intelligence and other functions on a virtualized layer, abstracted from the physical networking hardware. This separates the data plane from the control plane.
The OpenFlow protocol permits communication between the decoupled data and control elements. The lower-layer OpenFlow protocol often is connected with SDN switches, and comes recommended by the Open Network Foundation.
But it needs to be put into perspective, said Brad Casemore, director of research for data center networks at IDC in Framingham, Mass. "Network virtualization can be done in other ways, and OpenFlow plays a relatively small role," he said. "It makes a lot of sense for deployment on physical switches but [it] is really keyed to hardware lifecycles and the deployment decisions of vendors."
Vendors that do not rely on OpenFlow switch protocols include network industry heavyweights Juniper and Brocade, and virtualization leader VMware (with its Nicira acquisition), to name a few. Other vendors, such as Cisco, support but do not mandate OpenFlow switches.
Issues with security, scalability and the need for specialized hardware deter users from OpenFlow and call upon the need for other protocols. Others to consider when implementing an SDN architecture range from the Simple Network Management Protocol to the Open vSwitch Database Management Protocol, Location Identifier Separation Protocol and vendor-specific flow controllers, among many others. As standards develop around software-defined networking, having specialized knowledge about protocols will become less important.
Author Alan R. Earls contributed to this answer. See what he recommends to prepare the data center for SDN.