A lot of the terminology surrounding can be confusing and we hope this VNF primer will help with VNF basics. At the core of any network function virtualization (NFV) implementation is a set of application images that need to be managed. Each of those images is made up of elements known as Virtual Network Function components (VNFCs). Those components can they be combined in multiple ways to create a virtual network function (VNF) that can be deployed anywhere to provide a networking service that previously would have required a dedicated physical appliance to deliver. In some instances, a VNFC is a discrete networking function. But a VNFC can also manifest itself as a more granular set of functions that could combined to create a larger VNF.
Those VNFs are then centrally managed via a Network Function Virtualization (NFV) framework that provides a layer of management and orchestration (MANO) that can be applied across multiple VNFs. That approach effectively creates a layer of isolation between the VNFs and the management and control planes employed to manage them that makes it simpler to both scale VNF deployments in addition to providing the control plane through which VNFs can interoperate with one another.
The NFV framework is a virtualization framework aimed at telco workloads. Many organizations are deploying NFV frameworks in conjunction with SDN (software-defined networking) frameworks that span both physical and virtual appliances, including routers and switching gear. That approach not only makes it simpler to manage a heterogenous networking environment, it also provides a consistent set of application programming interfaces (APIs) that can be invoked to programmatically control various elements of the network in a consistent manner.
How NFV frameworks will interact with VNFs is defined by the European Telecommunications Standards Institute (ETSI). A NFV Release 2 specification published by ETSI last fall (2016) builds on a previous release that defined 11 specifications for NFVs spanning descriptions of the compute, hypervisor and network domains of the infrastructure, management and orchestration, security and trust, resilience and service quality metrics as well as providing an overview of an updated architectural framework.