Don't Panic — Network Function Virtualization

Network Function Virtualization, or NFV, is the decision to run a network function as software on virtualized infrastructure instead of receiving the function bolted to one dedicated appliance. The appliance did not vanish in a puff of responsible accounting. Its job was separated from the compute, storage, and network resources that host it.

The useful unit is a Network Service, not a lonely virtual machine trying to look important. A service can combine Virtualized Network Functions, physical network functions, and the connectivity between them. That last part matters. A firewall, router, or traffic optimizer does not become a service merely because it has started. Traffic still needs a path, and some functions still remain tied to special hardware. NFV is comfortable with this mixed arrangement, which is more realistic than insisting that every useful thing has the same shape.

The three names that prevent most diagrams from becoming decorative wallpaper are NFVI, NFVO, and VNFM. NFV Infrastructure supplies the compute, storage, and network resources. The NFV Orchestrator coordinates Network Service resources and lifecycle. The VNF Manager manages the lifecycle of a VNF. The Virtualized Infrastructure Manager controls the virtualized infrastructure resources. They have different jobs because changing a service, changing a function, and changing the place it runs are different kinds of trouble.

A descriptor is the written contract that says what a VNF or service needs and how its constituents connect. It is not a magical performance certificate. Latency, throughput, availability, isolation, and observability still depend on the deployed function, connectivity, and infrastructure together. This is the small print that turns out to be most of the print.

Read the introduction when you need the architecture and its vocabulary in one place. Use the slides for the relationships between service, MANO, and NFVI. Keep the cheatsheet nearby when NFVO, VNFM, VIM, PNF, and descriptor begin behaving like a bowl of abbreviations. Then follow the reference links to the ETSI architecture and an implementation such as Open Source MANO, where the lifecycle model has to meet actual operations.

Don't Panic — Network Function Virtualization

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