In this chapter, we talked about programmable networks, more specifically, how OpenFlow works, the different OpenFlow controllers available, and the hardware that can use OpenFlow.
OpenFlow was conceived at Stanford in their Clean Slate lab as a way to overcome the limitations of current networking and allow for programmable (SDN) networks. The OpenFlow standards original release version was 0.8.9 and has moved to 1.5 at this time.
OpenFlow version 1.0 was functional but only utilized one table, partly due to the limitations of the hardware at the time. In OpenFlow 1.1 multiple tables were introduced, helping to push OpenFlow further into mainstream networking. Today most vendors are standardized on OpenFlow version 1.3, a few support 1.4 but are backwards compatible.
In the next chapter, we will discuss REST and Thrift-based APIs.