Do you need to use the OpenFlow protocol in a software-defined network?
The OpenFlow protocol is not required to implement a software-defined network (SDN) to separate the data path from the control plane and tell network switches where to send packets. SDN architectures will take many different approaches, and each technology vendor will have a unique take on how to implement SDN.
For the OpenFlow community that uses standards developed by the Open Network Foundation (ONF) consortium, however, the answer is yes. The ONF recommends using OpenFlow as the foundation technology for SDN implementation. For many suppliers, including Big Switch, HP, IBM, Dell, Pica8, NEC and many others, OpenFlow is a fundamental part of their SDN offerings.
Many other suppliers may support OpenFlow, but the protocol is not of the key to their SDN architectures. For example, Cisco's SDN architecture, Open Network Environment, supports OpenFlow, but Cisco does not require the use of OpenFlow. Other suppliers that offer SDN solutions that do not depend on the OpenFlow protocol include Juniper, Brocade, Avaya, ADARA, LineRate, Embrane, Nicira (now part of VMware), PlumGrid, Pertino Networks, Plexxi and many others.