What is software-defined networking?

Software-defined networking (SDN) is an approach to IT infrastructure that abstracts networking resources into a virtualized system. SDN separates network forwarding functions from network control functions with the goal of creating a network that is centrally manageable and programmable. SDN allows an IT operations team to control network traffic in complex networking topologies through a centralized panel instead of handling each network device manually.

Organizations adopt software-defined networks in reaction to the constraints of traditional infrastructures. Some of the benefits of software-defined networking include:

• Lower cost - Software-defined network infrastructures are often less expensive than their hardware counterparts because they run on commercial-off-the-shelf servers rather than expensive single-purpose appliances. They also occupy a smaller footprint since multiple functions can be run on a single server. This means that less physical hardware is needed, which allows for resource consolidation that results in less of a need for physical space, power, and overall reductions in cost. 
• Greater scalability and flexibility - Virtualizing your network infrastructure allows you to expand or contract your networking resources as you see fit—and when you need them—instead of scrambling to add another piece of proprietary hardware. Having a software-defined network puts enormous flexibility in your hands which can enable self-service provisioning of network resources.
• Simplified management - A software-defined network leads to an overall easier-to-operate infrastructure because it does not require highly specialized network experts to manage it. 

Software-defined networking, when coupled with software-defined storage and other technologies, can comprise an approach to IT infrastructure known as hyperconvergence: a software-defined approach to everything.

For telecommunications companies there is another kind of network abstraction called network function virtualization (NFV). Like software-defined networking, NFV abstracts network functions from hardware. NFV supports software-defined networking by providing the infrastructure on which SDN software can run. NFV gives providers the flexibility to run functions across different servers or move them around as needed when demand changes. This flexibility lets telecommunications service providers deliver services and apps faster. For example, if a customer requests a new network function, they can spin up a new virtual machine (VM) to handle that request. If the function is no longer needed, the VM can be decommissioned. This can be a low-risk way to test the value of a potential new service.

NFV and SDN can be used together, depending on what you want to accomplish—and both use commodity hardware. With NFV and SDN, you can create a network architecture that is more flexible, programmable, and uses resources efficiently.