VNF

A VNF is a network function delivered as software you run on shared infrastructure instead of a purpose-built appliance. Take a function that used to be a dedicated box — a firewall, a router, a core element — and run it as a virtual machine (or set of VMs) on standard servers, and you've got a VNF. It's the concrete instance of the idea that NFV promotes at the architecture level.

The practical payoffs are familiar from any virtualization story: you scale by spinning up more instances, you place functions where capacity is, and you upgrade software without truck rolls. The term is most associated with VM-based deployments; the container-native equivalent is usually called a CNF (Cloud-native Network Function), which packages the function as microservices on Kubernetes rather than full VMs. A VNF is managed by a VNF Manager within the broader NFV MANO framework, which handles its instantiation and lifecycle on the virtual infrastructure.