The OpenFlow controller provides the interfaces to the OpenFlow switches on one side and the required API for the development of Net Apps.

In this chapter, the overall functionality of OpenFlow (SDN) controllers were presented and some of the existing implementations (NOX/POX, NodeFlow, and Floodlight) were explained in more detail. NOX was the first OpenFlow controller written in Python and C++. POX is a general, open-source SDN controller written in Python. A learning Ethernet switch Net App, based on the API of POX, was presented. NodeFlow is an OpenFlow controller written in JavaScript for Node.js.

Floodlight is a Java-based OpenFlow controller, based on the Beacon implementation, that works with physical and virtual OpenFlow switches. FlowVisor and RouteFlow as special controllers were also presented in this chapter.

Now, we have covered all the required material in order to set up our SDN/OpenFlow development environment. In the next chapter, this environment will be set up.