Network Functions Virtualization (NFV)

Network Functions Virtualization aims to transform the way that network operators architect networks by evolving standard IT virtualisation technology to consolidate many network equipment types onto industry standard high volume servers, switches and storage, which could be located in Datacentres, Network Nodes and in the end user premises, as illustrated in Figure 1.

It involves the implementation of network functions in software that can run on a range of industry standard server hardware, and that can be moved to, or instantiated in, various locations in the network as required, without the need for installation of new equipment.

Benefits of Vurtualizing network functions include:

• Reduced equipment costs and reduced power consumption through consolidating equipment and exploiting the economies of scale of the IT industry.
• Increased speed of Time to Market by minimizing the typical network operator cycle of innovation. Economies of scale required to cover investments in hardware-based functionalities are no longer applicable for software-based development, making feasible other modes of feature evolution. Network Functions Virtualization should enable network operators to significantly reduce the maturation cycle.
• Availability of network appliance multi-version and multi-tenancy, which allows use of a single platform for different applications, users and tenants. This allows network operators to share resources across services and across different customer bases.
• Targeted service introduction based on geography or customer sets is possible. Services can be rapidly scaled up/down as required.
• Enables a wide variety of eco-systems and encourages openness. It opens the virtual appliance market to pure software entrants, small players and academia, encouraging more innovation to bring new services and new revenue streams quickly at much lower risk.

To leverage these benefits, there are a number of technical challenges which need to be addressed:

• Achieving high performance virtualized network appliances which are portable between different hardware vendors, and with different hypervisors.
• Achieving co-existence with bespoke hardware based network platforms whilst enabling an efficient migration path to fully virtualized network platforms which re-use network operator OSS/BSS. OSS/BSS development needs to move to a model in-line with Network Functions Virtualization and this is where SDN can play a role.
• Managing and orchestrating many virtual network appliances (particularly alongside legacy management systems) while ensuring security from attack and misconfiguration.
• Network Functions Virtualization will only scale if all of the functions can be automated.
• Ensuring the appropriate level of resilience to hardware and software failures.
• Integrating multiple virtual appliances from different vendors. Network operators need to be able to “mix & match” hardware from different vendors, hypervisors from different vendors and virtual appliances from different vendors without incurring significant integration costs and avoiding lock-in.

Relationship with Software Defined Networks (SDN)

As shown in Figure 2, Network Functions Virtualization is highly complementary to Software Defined Networking (SDN), but not dependent on it (or vice-versa). Network Functions Virtualization can be implemented without a SDN being required, although the two concepts and solutions can be combined and potentially greater value accrued.