Intelligent CIO Middle East Issue 20 | Page 36

FEATURE: SDN What is virtualisation of networks? By Arun Shankar P roduct development within the telecommunications industry has traditionally followed rigorous standards reflected by the term ‘carrier grade’. While this model worked well in the past, it inevitably led to long product cycles, a slow pace of development and reliance on proprietary hardware. Network function virtualisation is a network architecture concept that uses IT technology to virtualise entire classes of network node functions into building blocks that may connect, or chain together, to create communication services. Network function virtualisation relies upon, but differs from, traditional server-virtualisation techniques. A virtualised network function may consist of one or more virtual machines running different software and processes, on top of standard high-volume servers, switches and storage devices, or even cloud computing infrastructure, instead of having custom hardware appliances for each network function. For example, a virtual session border controller could be deployed to protect a network without the cost and complexity of installing physical network protection units. Network function virtualisation framework consists of three main components: Virtualised network functions: These are software implementations of network functions. Network functions virtualisation infrastructure: This is hardware and software components that build the environment where virtualised network functions are deployed. To build more complex services, the notion of service chaining is used, where multiple virtualised network functions are used in sequence to deliver a service. Another aspect of implementing network function virtualisation is the orchestration process. To build highly reliable and scalable services, network function virtualisation requires that the network be able to initiate virtualised network function instances, monitor them, repair them, and most important for a service provider business, bill for the services rendered. These attributes, referred to as carrier-grade features, are allocated to an orchestration layer in order to provide high availability and security, and low operation and maintenance costs. The initial perception of network function virtualisation was that virtualised capability should be implemented in datacentres. This approach works in many, but not all cases. Network function virtualisation presumes and emphasises the widest possible flexibility as to the physical location of the virtualised functions. Virtualised functions should be located where they are the most effective and least expensive. That means a service provider should be free to locate network function virtualisation in all possible locations, from the datacentre to the network node to the customer premises. This approach is known as distributed network function virtualisation. Network functions virtualisation management and orchestration architectural framework: This is a collection of functional blocks, data repositories, reference points, interfaces through which these blocks exchange information for the purpose of orchestration. Network function virtualisation is a software platform running on standard multi-core hardware and built using open source software that incorporates carrier-grade features. The network function virtualisation platform software is responsible for dynamically reassigning virtualised network functions due to failures and changes in traffic load, and therefore plays an important role in achieving high availability. There are numerous initiatives underway to specify, align and promote network function virtualisation carrier-grade capabilities. The network function virtualisation platform implements carrier-grade features to manage the platform components, recover from failures and provide effective security, all required for public carrier networks. A service provider that follows the network function virtualisation design implements one or more virtualised network functions. A virtualised network function by itself does not automatically provide a usable product or service to the provider’s customers. Virtualisation is also changing the way availability is measured in network function virtualisation solutions. As virtualised network functions replace traditional function-dedicated equipment, there is a shift from equipment-based availability to a service-based, end-to- end, layered approach. Virtualising network functions breaks the explicit coupling with specific equipment, therefore availability is defined by the accessibility of virtualised network function services . ¡ 36 INTELLIGENTCIO www.intelligentcio.com