Network function virtualization

Network Functions Virtualization (NFV) is a network architecture concept that proposes using IT virtualization related technologies, to virtualize entire classes of network node functions into building blocks that may be connected, or chained, together 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 industry 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 virtualized session border controller function 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.

Background

Product development within the telecommunications industry has traditionally followed rigorous standards for stability, protocol adherence and quality. While this model worked well in the past, it inevitably led to long product cycles, a slow pace of development and reliance on proprietary or specialist hardware. The rise of significant competition in communications services, from fast-moving organizations operating at large scale on the public Internet (such as Google Talk), have spurred service providers to look for ways to disrupt the status quo.

History

In October 2012, an industry specifications group, "Network Functions Virtualisation", published a white paper at a conference in Darmstadt, Germany on software-defined networking and OpenFlow. The group, part of the European Telecommunications Standards Institute (ETSI), was made up of representatives from the telecommunications industry from both Europe and beyond.

Since the publication of the white paper, the group has produced several more in-depth materials, including a standard terminology definition and use cases for NFV that act as references for vendors and operators considering implementing NFV.

Practical aspects

A service provider who follows the NFV design will implement one or more virtualized network functions, or VNFs. A VNF by itself does not automatically provide a usable product or service to the provider's customers. To build more complex services, the notion of service chaining is used, where multiple VNFs are used in sequence to deliver a service.

Another aspect of implementing NFV is the orchestration process. In order to build highly reliable and scalable services, NFV requires that the network be able to instantiate VNF instances, monitor them, repair them, and (most importantly for a service provider business) bill for the services rendered. This complex task is allocated to an orchestration layer. Importantly, the orchestration layer must be able to manage VNFs irrespective of what the underlying technology within the VNF is. For example, an orchestration layer must be able to manage an SBC VNF from vendor X running on VMware vSphere just as well as an IMS VNF from vendor Y running on KVM (Kernel-based Virtual Machine).

Distributed NFV

The initial perception of NFV was that virtualized capability should be implemented in data centers. This approach works in many – but not all – cases. NFV presumes and emphasizes the widest possible flexibility as to the physical location of the virtualized functions.

Ideally, therefore, virtualized functions should be located where they will be the most effective and least expensive. That means a service provider should be free to locate NFV in all possible locations, from the data center to the network node to the customer premises. This approach, known as Distributed NFV, has been emphasized from the beginning as NFV was being developed and standardized, and is prominent in the recently released NFV ISG documents.

For some cases there are clear advantages for a service provider to locate this virtualized functionality at the customer premises. These advantages range from economics to performance to the feasibility of the functions being virtualized.

Relationship to SDN

SDN, or software-defined networking, is a concept related to NFV, but they refer to different domains. SDN is focused on the separation of the network control layer from its forwarding layer, while NFV is focused on porting network functions to virtual environments in order to enable the migration from proprietary appliance based embodiments to a standard hardware and cloud based infrastructure.

Both concepts can be complementary, although they can exist independently.

Industry impact

NFV has proven a popular standard even in its infancy. Many major network equipment vendors have announced support for NFV.

Some notable early adopters of NFV include:

• Alcatel-Lucent
• Allot
• Arista Networks
• Avaya
• Brocade
• Cisco
• Connectem
• Cyan
• Dell
• Hewlett-Packard
• Huawei
• Mavenir
• Mellanox Technologies
• Metaswitch
• Nakina Systems
• NEC
• Openet
• Overture Networks
• Openwave Mobility
• Procera Networks
• RAD
• Sandvine
• Tail-f
• Wedge Networks Inc.
• Wind River
• 6Wind
• MANO

See also

• Hardware virtualization
• Software-defined networking
• Network virtualization
• Network management
• Management and orchestration