Definition — What is an SDN? 

Software Defined Networking (SDN) is an architecture that gives networks more programmability and flexibility. In 2009, Kate Green from MIT Technology coined the term Software Defined Networking.

In conventional networks, IT devices have both Control plane and Data plane functions consolidated into a single physical platform. In such a network, routing and switching decisions are made by each discrete device on a distributed basis. SDN separates the Control plane and Data plane functions of the networking infrastructure and allows the decision-making part to happen in a software application, this helps the network administrator to manage the traffic through software from a centralized location. The added advantage is that Network engineers need not wrangle individual network devices to offer network services or govern resource and capacity utilization. Instead, SDN takes care of this task, directing these individual switches to provide services when the business requires them. SDN is crucial to enterprise businesses because it gives network operators new ways to design, build, and operate their networks.