Introduction to Software-Defined Networking
While it's fairly easy to get a generic description of what software-defined networking is, different sources are going to provide different descriptions, because this general IT architecture can be set up in many different ways. SDN isn't something that's monolithic in terms of its build – it's a central concept that companies are using to revolutionize IT products and services.
At the most basic level, software-defined networking is a networking technology that centralizes network management in a smaller number of components – the way that software-defined networking does this is to decouple the control plane from the data plane, which we will talk about more later.
Think of it this way – in more traditional networks, each individual network switch and component had its own decentralized control processes. By taking away this kind of atomized design and consolidating a lot of the control in a single “head” component – or a similar structure – vendors and other parties are able to help companies to scale hardware and software systems more easily. Instead of every single point of the network having all of its own controls, engineers place the control in a limited number of spots, saving key resources.
The key here is that this can be done in a variety of different hardware environments. Virtualization, a fairly new process of abstracting network components, has allowed for some of the innovations in software-defined networking, where smart applications or software programs run the networks. While smart hardware pieces can work together to offer software-defined networking systems, it's also possible to do away with a lot of the hardware completely and use virtualized setups instead.
Now, big companies have started to endorse the idea of SDN, and new products offer it through more sophisticated systems. Many “flavors” of SDN help companies to achieve efficiencies – to build networks that are, in some senses, “smarter” because they have smart software running their routing protocols.
The evolution of SDN is also taking place in a larger context – there's also the idea of a SD-WAN, which applies the same concept to a wide area network. With the emergence of cloud technologies, there's more of the SaaS model being applied to remotely manage systems, and “software-defined IT” is a new frontier.
It's important to understand that the world of SDN is diverse.
“In the broadest sense, any software that manages a network of dynamically assigned addresses – addresses which represent services provided or functions performed – is utilizing some variety of SDN,” writes Scott Fulton III at ZDNet, explaining that the term arises to distinguish new software-driven models from old hardware-driven ones and boiling down the idea of SDN into four words: “SDN is networking now.”