With the roll-out of 5G right around the corner, the need to develop more flexible and agile networks is being felt. This is where technologies such as software-defined networking (SDN), network function virtualisation (NFV) and software-defined wide area network (SD-WAN) come into the picture. These solutions can simplify and maintain the entire network efficiently while offering flexibi­lity in controlling traffic across the network, thereby improving network performance. To meet the rising demand for streaming and video-based applications, and social media platforms, telcos have been resorting to softwarisation and virtualisation to en­sure minimum intervention at individual sites. Going forward, as 5G networks become the norm globally, SDN/NFV and SD-WAN technologies will be crucial for building programmable, flexible and customisable networks.

SD-WAN leverages SDN principles

SD-WAN combines the tenets of SDN with those of distributed WAN, simplifying control and easing the flow of information to the cloud. For large enterpri­ses with increasingly distributed and complex IT infrastructure, the challenge is in managing the network with full visibility, while having the scalability to grow and meet new business objectives. The combined use of SDN and SD-WAN can support an en­terprise’s cloud-first strategy. Enterpris­es can leverage an SDN platform to interconnect global data centres and secure a direct connection to the cloud via a private carrier ethernet network fabric. SDN and 5G are expected to transform network ca­pabilities by bringing in significant opportunities for network virtualisation, artificial intelligence and automation, while lo­wering associa­ted costs considerably and enhancing delivery of network-based ser­vi­ces, IT systems and applications.

Role of SDN/NFV in 5G deployments

A key feature unique to 5G is network programmability. In the 5G era, a gamut of new communication demands will em­er­ge from a range of devices, users and companies. To sufficiently manage these dema­n­ds, 5G networks will have to be programmable, flexible, modular, and software-driven, and managed in such a manner that they support a diverse range of se­r­vi­ces. SDN te­chnology can play a key role in this rega­rd by enabling network pro­g­­ramming. A prog­rammable 5G network provides service agility, by reducing the time needed for service creation and adaptation; service diversity, by having a single infrastructure for multiple services with a wide range of requirements; and resource efficiency, by dynamically allocating the right number of resources wherever needed.

Another disruptive concept that will emerge in the 5G era is network slicing. Through network slicing, a single 5G phy­sical network can be sliced into multiple isolated logical networks of varying sizes and structures, dedicated to different types of services. This will allow operators to create different levels of services for different enterprise verticals, enabling them to customise their operations.

When combined with SD-WAN, high speed 5G services provide distributed organisations with improved reliability, rapid provisioning and high speed bandwidth. Further, when SD-WAN is combi­n­ed with fast cellular wireless connecti­vity, it enables a new WAN architecture with significant benefits to enterprises that have large numbers of employees in hybrid or permanent work-from-home settings.

Meanwhile, by leveraging NFV, operators can implement a string of network-connected devices without investing in ex­pensive proprietary hardware. These network functions can be set up in a few

we­­e­ks, unlike proprietary hardware, which ta­k­es months to install. In terms of 5G, NFV aids virtualisation of multiple layers. Particularly, NFV allows 5G network slicing, which permits numerous virtual net­wo­r­ks to function on top of the same physical infrastructure. Further, NFV allows service providers to dynamically create

se­r­­vice chains in the network, depending up­on the type of 5G service. This grants fl­exibility to service providers and enables them to scale services up/down to address changing customer demands. It also redu­ces their capital and operational expenditure through lower-cost, agile network infrastructure, and decreases the deployment time of new network services.

Coordinated play

SD-WAN and NFV are complementary and form a powerful combination when used together. Both can easily be deployed in enterprise or cloud data centres with SD-WAN service chaining, or distributed as virtual services all the way to branches. By leveraging NFV services with SD-WAN, service deployments can be made in batches across the enterprise, and simplify service insertion at branches. Addi­tio­nally, while NFV is typically used to deploy services in the cloud, it can be used with SD-WAN to deliver these cloud services across the entire organisation to each remote location. Moreover, SDN and NFV represent a core structural transformation in the way communication infrastructure is dep­loy­ed. These technologies have induc­ed significant improvements in the time-to-market, cost efficiencies and innovation, helping the industry build agile networks at lower costs. SDN and NFV implementations remove the compulsion to relay data in flat networks back to the core. Creating cores at different levels enables local caching of data on edge devices which, in turn, considerably lowers latency and increases reliability across networks. Over­all, SDN and NFV are integral to 5G, en­ab­ling seamless management of billing, mobility and network authentication.

Key use cases

Mobility with the help of SDN

A key challenge in wireless and broadband networks concerns multi-homing – connecting the end host to multiple networks si­multaneously so that users can move

fr­­eely between wireless infrastructures, and the provider can support them. This app­roach will emerge by applying SDN capabilities to relays between a home network and perimeter networks. The architecture that would arise from using SDN and NFV between a home gateway and an ac­c­ess network would transfer most of a ga­teway’s functionality to a virtualised run­time environment.

M2M communications

As part of future wireless networks, end users will need to communicate with each other and with surrounding objects and machines, such as with sensors embedded in objects. Wireless SDN (WSDN) will be a crucial concept for controlling machine-to-machine (M2M) networks. WSDN drivers must provide flexibility to support node mobility, topology discovery, self-configuration and self-organisation.

Cooperative networks

In other aspects, SDN and NFV will di­­rec­tly impact cooperative networks. To make data exchange between networks se­­amless, SDN can provide advanced ca­ch­ing techniques for data on the perimeter network to achieve the high capacity required of 5G systems.

Challenges hampering deployment

While SDN and NFV technologies pro­mise a variety of benefits, they are not free of challenges. These challenges include:

Orchestration and integration in hybrid networks

While NFV is promoted as being built on industry-standard hardware and software, service providers sometimes still face vendor lock-in. To make it work, software elements need to be fully interoperable. The resulting network should be rapidly flexible and scalable, and should benefit from dynamic resource allocation. A flexible, automated and programmable orchestration platform is a must to cope with this requirement.

Lack of capabilities

As SDN and NFV are in their earliest sta­ges, it is no surprise that NFV presents an opportunity to decrease operational ex­pen­diture and enhance customer experience. One obstacle is the lack of vendor solutions, as well as the reduced adoption of technologies that enable service provi­ders to embrace the capabilities needed to operationalise SDN/NFV. Migrating to SDN and NFV shifts service providers’ networks from hardware-centric, semi-static connectivity platforms to software-driven, dynamic service platforms. It is a transformative event and will remain inhibited until service providers begin to make that shift.

Security and privacy

Another major challenge associated with SDN- and NFV-based networks concerns security. Operators have now started in­troducing various virtualised network elements, including virtualised evolved packet core, virtualised IP multimedia services, virtualised residential gateway and virtualised next-generation firewalls, in their access and core networks. However, very little attention has been given to the security aspects of virtualisation.

The way forward

Net, net, SDN and NFV technologies form the backbone for building programmable, flexible and customisable 5G netwo­rks. The adoption of these solutions pro­vides the ability to manage and for provision of network services from a centra­li­sed lo­cation, enabling faster and more cost efficient delivery of bandwidth on demand, with minimal disruptions. More­over, the cl­oud architecture that SDN and NFV so­lutions use has features such as data analytics and automation, which are not available in legacy networks. Telcos can leverage the emerging opportunities in the enterprise space and partner with various IT vendors to help enterprises across industry verticals build programmable and flexible networks. SDN/NFV and SD-WAN are technologies that have become extremely essential for leveraging the full potential promised by 5G networks.

With 5G roll-out around the corner, network providers are expected to em­b­ra­ce technologies such as SDN and NFV, which form an integral part of the 5G ecosystem.