In just a few short recent years the idea of software-defined networks (SDN) has moved from a theoretical academic concept to a real-life practical proposition for making the world’s telecommunications networks more efficient, cost-effective, easier to manage and resilient. The SDN concept really started to take shape around 2008 [1], Google and Facebook have already implemented important features of SDN in their own networks. Now most major carriers are planning to move in the SDN direction, for example Deutsche Telekom [2, 3] and more recently AT&T [3] to reduce high operational costs while the over-the-top providers (e.g., Google, Amazon, etc.) impede the carriers’ ability to grow their revenues.
Put simply, the SDN idea is to separate out the control functions of the network into a cloud-like management layer leaving network elements in a data-forwarding layer. This means the smart component of networks can be made more efficient and less expensive by making use of the concepts of abstraction, modularity and virtualization that are already common in the IT world. At the same time the basic network building blocks – essentially the bit-carrying hardware – can be less expensive because they will become simpler and dumber.