Network Functions Virtualisation (NFV) completely changes how communication networks are designed, built and managed by pulling the functions necessary to run networks off proprietary hardware and placing them on open-architecture-based servers. Network element functions can then be deployed where required, when required, and scaled on demand, thus greatly improving infrastructure utilisation, significantly improving the network cost curve growth, and enabling faster, more flexible service introduction, writes Ronnie Neil.
NFV liberates communications service providers (CSPs) from many existing network constraints and complexities. Networks become more scalable, more dynamic by allowing changes in real-time, and more cost effective to operate over their lifetime. NFV also makes network management more flexible with the potential to deliver better performance and customer service while providing a more agile 
environment for the introduction of new services and applications.
Market drivers and challenges
The market for NFV is nascent, although it is projected to surge over the next few years as CSPs look tobolster service offerings and cut costs. Almost all parts of a service provider’s network can benefit from virtualisation including the customer premises – both business and residential, although the mobile core is likely to be one of the first areas where providers will introduce virtualisation. Some of the main market drivers for NFV include:
• Optimised equipment and infrastructure costs by consolidating network functions while exploiting economies of scale from the IT industry
• Improved scalability by using a single platform for different applications and users
• Accelerated time-to-market by shrinking typical innovation cycles for new services and applications
• Expanded collaboration resulting from open environments, enabling a wide variety of ecosystems and partnerships
To deliver on the benefits of NFV, however, some major challenges will need to be overcome. Networks of the future will be designed, implemented and managed radically differently than they are today. Network performance, once predictable in a dedicated, hardware-based network appliance, will be affected in many new ways when a virtual network element is installed or reconfigured. Today, physical links connecting network equipment are points of delineation and locations where data can be accessed for monitoring and troubleshooting. In the future, these physical links will be virtual interfaces, connecting functions within software in the same – or different – virtual machines within a physical server. Today’s methods and tools to identify which subscribers are impacted by poor network performance, where and why, will need to be replaced or adapted.
Forcing major OSS transformation
Operational support systems (OSS) and their associated processes are at the heart of delivering and maintaining today’s communication networks and services. Most CSPs have – at least – tens of OSS, each performing a specific function in areas such as network inventory, service provisioning, service assurance and customer care. These systems deliver a significant impact on the quality of experience that end-users receive, including service provisioning times, service uptimes and service quality. To perform their function, a large number of these systems interact directly with the network, especially those OSS involved with service provisioning and service assurance. For these systems in particular, NFV will introduce a fundamental disruption to their current mode of operation.
OSS that have traditionally interacted with statically configured network equipment, for tasks such as configuration, provisioning, performance monitoring, and fault management, will now interact with dynamic, virtual network equipment. In this new NFV world, how and where do OSS connect to the network? How do they cope when the network and their current access points dynamically reconfigure? And, how do they ensure that the NFV processes themselves are not introducing issues that impact the end-user quality of experience?
The transformation to NFV does create a significant opportunity to cost-effectively and quickly deliver revolutionary services at breakthrough price points. However, there are two major obstacles to overcome – the successful introduction of virtualised network infrastructure itself and the evolution of the associated OSS and processes.
Evolution not revolution
The limitations and shortcomings of legacy OSS will be a major barrier to the wide-scale adoption of NFV. But how do these systems need to change? Firstly, as service providers virtualise their networks and adopt cloud-based architectures, it is vital that the OSS support virtualised environments. That is, the OSS software must operate in virtual environments, support emerging virtualisation protocols like OpenStack, and be deployable in a variety of public, hybrid and private cloud environments.
To keep pace with the dynamic nature of virtual networks, OSS must be able to adjust on a real-time basis in terms of capacity, resources and configuration. To know how to adjust, the OSS must link into NFV management functions to receive information on how the network has configured itself. Some OSS will also have to link into operational policy systems as network configurations will be adjusted according to specific customer service level agreements, security requirements, and traffic patterns. Open, standards-based application programming interfaces (APIs) will be crucial to the seamless integration of OSS with the NFV management infrastructure.
Performance-based OSS will be increasingly important in a virtualised environment including playing a vital role in the management of the NFV infrastructure itself. NFV infrastructure enables automatic reconfiguration of a network, but to be a success, the reconfiguration needs to deliver either better customer experience and/or lower operational costs. Real-time performance data will be a key input into the operational policy systems formulating the NFV reconfiguration decisions.
For all CSPs, NFV will drive a profound change to their network and business processes. So, while NFV can unlock dramatic new operational efficiencies and service delivery benefits, these gains may be limited unless the associated OSS are appropriately transformed and integrated with the NFV infrastructure. As the transition to NFV will take some time, the impacted OSS will be forced to support heterogeneous environments spanning both virtual and legacy networks. So the OSS changes, while major, will need to be an evolution, not a revolution. In a future article, we will examine in more detail how service management and assurance solutions must transform to meet the needs of an NFV-enabled virtualised environment.
