Modern telecom networks consist of a wide variety of proprietary hardware. However, the launch of a new generation of networks and services often demands network reconfiguration with greater flexibility and dynamism. Vir­tualisation allows networks to be agile, mo­dular and capable of responding automatically to the traffic needs and services running over them. The key enabling technologies for this are software-defined networking (SDN) and network functions virtualisation (NFV). While both SDN and NFV make networking architectures more flexible and dynamic, they perform different roles in defining the architectures and infrastructure they support. SDN provides the means to dynamically control the network and the provisioning of networks-as-a-service. Meanwhile, NFV allows managing and orchestrating the virtualisation of resources for the provisioning of network functions and their composition into higher-layer network services.

A look at the key benefits and the network testing and security aspects of these technologies…

Benefits to telcos

Vendor neutrality

Legacy vendors typically offer their services on dedicated hardware that is inflexible and hinders innovation. However, with the adoption of SDN and NFV technologies, network functions can be virtualised and run on commercially available off-the-shelf hardware. This approach enables service providers to share hardware across multiple network functions, providing the advantage of software decoupling and the ability to build a flexible virtual infrastructure. By leveraging these technologies, telecom operators can mix and match vendors and functions for different features. This reduces vendor lock-in and provides the freedom to choose hardware and software solutions from different vendors, fostering a more open and competitive network ecosystem. Moreover, the flexibility of NFV technology supports the use of open source tools and software services. This approach allows operators to leverage a wide range of software solutions, including those developed by the open source co­mmunity. By using open source tools and software, service providers can reduce costs and accelerate innovation while maintaining the flexibility to choose the best solution for their needs.

Centralised network processing

In traditional network architecture, intelligence and decision-making are distributed across the network. Although this eliminates failure, it increases the complexity of the network elements and leads to layers upon layers of protocols. In contrast, SDN provides centralised network management, allowing administrators to manage and configure the entire network from a single point of control. The decision-making in­telligence is with the centralised controller; this significantly reduces the complexity of network elements.

Cost savings

Virtualisation offers the capability to automate provisioning which, in turn, reduces human resource requirements, resulting in lower operating expenditure. Additionally, SDN brings together multiple compute, storage and processing functions onto low-cost commodity servers to reduce ca­pital ex­penditure.

Scalability and rapid deployment of network services

Scalability is a top priority for operators to meet new requirements and increase capacity. However, traditional network equipment can be difficult and expensive to up­grade. The programmable nature of SDN and NFV technologies makes it easier to design, deploy, manage and scale net­works. By abstracting the control pla­ne in SDN, adding or removing network re­sources and scaling the network can be done more easily and without manual configuration on each individual device. NFV also enables operators to deploy new solutions and features into production rapidly by decoupling software functionality from physical hardware. This approach eliminates the need for lengthy change requests or new appliances from le­gacy vendors, resulting in a fa­s­ter and more agile deployment process.

Operational efficiency

NFV enables the use of machine-to-ma­chine tools to their fullest potential. These tools automatically detect when a network function requires more memory or other resources, reducing downtime and enhancing network maintenance activities. It allo­ws in-service software upgrades and 24×7 self-healing networks. Thus, it minimises operational losses due to network outages and provides smooth, uninterrupted customer service. SDN also enables the separation of the control plane and data plane, enabling operators to dynamically control and adapt network behaviour according to changing requirements.

Optimal utilisation of network resources

One of the major shortcomings of legacy network architectures is that applications have little to no visibility of resources available at the network layer. Hence, the re­so­urce requirements are not precise and network elements are mostly overprovisioned. In SDN architecture, the centralised controller can view the resource requirements of the applications and is able to match th­em against the resource availability, resulting in optimal utilisation of network re­sour­ces. It allows for traffic prioritisation, quality of service enforcement, and dynamic allocation of network resources based on real-time requirements.

Lower energy consumption

A critical benefit of SDN and NFV is their ability to reduce energy consumption in net­work operations. For instance, NFV all­ows network administrators to focus the workload on fewer servers during off-peak hours so that all other servers can be swit­ched off or put on energy-saving mode. It can considerably reduce energy usage, re­sulting in lower operational costs and a smaller carbon footprint.

Debate on security

SDN provides a central point of control to distribute security and policy information across the network. It enables the implementation of security policies, access control mechanisms, and traffic monitoring and analysis, enhancing the overall network security. SDN security applications are capable of acting on any anomalies by di­ver­ting specific network flows to special en­forcement points or security services, such as firewalls and intrusion detection­/pre­vention systems. It also allows operators to selectively block malicious traffic thro­u­ghout the network on a granular basis.

However, a number of security risks associated with SDN/NFV deployment ha­ve been identified. The most obvious downside of SDN is that attackers have to access only a single node in the network, the SDN controller, to breach the entire network security. The SDN controller ma­kes each device in the network more se­cure, but it makes the network as a whole vulnerable to a single attack against the SDN controller. Moreover, a single server may operate several different tenants’ virtual resources, or a single tenant’s virtual re­source might be distributed across several servers. Multitenancy resource sharing introduces the risks of data leaks. The multivendor environment also complicates se­curity problems. Furthermore, NFV environments are inherently complex, with multiple layers that are hard to secure with blanket security policies.

The key to achieving effective end-to-end security across virtualised and highly distributed networks is security automation. This comprises automated real-time monitoring to prevent threats, and protection systems to provide swift responses to threats and attacks. Experts suggest that such an approach to SDN/NFV security needs to consider the current standards and specifications provided by the Euro­pe­an Telecommunications Standards Ins­titute (ETSI) and 3rd Generation Part­ner­ship Project (3GPP) on 5G and NFV systems. The Department of Tele­com­muni­cations (DoT) recently initiated an exercise to frame security standards around NFV. The National Centre for Communication Se­curity, a unit under DoT, has started work on framing security standards that will be binding on telecom operators and equipment makers in India.

Network testing

As networks evolve towards NFV, the model of traditional monolithic network functions and single-vendor solutions will transform to virtualised architectures from multiple vendors. As such, traditional testing tools and methodology must also ev­olve to incorporate the broader scope of configurations. Different types of testing methodologies have been defined by the Interna­tional Telecommunication Union and ETSI. Broadly, these include interoperability testing, conformance testing and performance testing. According to industry experts, all components of virtualised networks need to be separately tested. In­tero­perability between these components and the conformance of their interfaces to specified standards should be tested. Additio­nally, performance testing needs to be executed not only in the design phase to provide infrastructure and resource requ­ire­ments but also post-deployment to en­sure that the virtual network function de­livers the expected performance.

The bottom line

NFV and SDN form the backbone of flexible and programmable networks. These solutions allow for the provision of network services from a centralised location, facilitating faster and more economical delivery of bandwidth on demand with minimal disruptions. Today, with the rapid proliferati­on of 5G networks, SDN and NFV dep­lo­y­ments have finally begun to pick up pace.

Although these technologies offer opportunities for security, they also introduce additional security challenges and co­mplexities in some cases. While several sta­ndardisation bodies such as ETSI, 3GPP, ITU and GSMA have released gui­delines to address these security issu­es, greater involvement of the security ecosystem including vendors, operators, resear­ch­ers and regulators is required to fully le­verage the benefits of virtualisation.