Network-function virtualization (NFV) is a network architecture concept that proposes using the technologies of IT virtualization to virtualize entire classes of network node functions into building blocks that may be connected, or chained, to create communication services.
NFV relies upon, but differs from, traditional server-virtualization techniques, such as those used in enterprise IT. A virtualized network function, or VNF, may consist of one or more virtual machines running different software and processes, on top of standard high-volume servers, switches and storage, or even cloud computing infrastructure, instead of having custom hardware appliances for each network function.
For example, a virtual session border controller could be deployed to protect a network without the typical cost and complexity of obtaining and installing physical units. Other examples of NFV include virtualized load balancers, firewalls, intrusion detection devices and WAN accelerators.