The recent exponential surge in data traffic, coupled with an ever-increasing network complexity, has made it im­perative for telecom operators to deploy so­lutions that can help them scale up their networks easily without compromising on the service quality. To this end, software-de­fi­ned networking (SDN) and the com­plem­entary technology, network functions vir­tu­­alisation (NFV), have emerged as pro­mi­sing solutions to help operators im­prove the automation capability, flexibility and interoperability of their network designs.

In contrast to traditional network ar­­­chi­tecture that comprises expensive hardware-based appliances with software tightly embedded in them, SDN and NFV decouple the functioning of the networks from their physical infrastructure, thereby making them more efficient and agile. SDN architecture uses software-based

co­ntrollers or application programming in­­ter­faces to communicate with the underlying hardware infrastructure and direct traffic on a network. SDN can help operators create and control a virtual network as well as manage the traditional hardware th­rough software.

A key application of SDN technology that has gained widespread traction over the past few years is software-defined wide area networks (SD-WAN). SD-WAN is a virtual WAN architecture that allows enterprises to leverage any combination of transport services including multiprotocol label switching, long term evolution and broadband internet services to securely connect users to applications. While traditional WAN based on conventional rou­ters requires backhauling of all traffic from branch offices to a hub or a data centre at headquarters, SD-WAN technology uses a centralised control function to securely and intelligently direct traffic across the WAN. This increases application performance, enhances user experience and reduces IT-related costs.

Meanwhile, NFV moves traditional net­work functions such as load balancers, firewalls, subscriber policy management and mobile radio access network out of physical hardware, and runs them as virtual network functions. NFV thus transforms networks into more open and programmable frameworks with the help of a centralised control layer. This helps operators optimise network resources, resulting in reduced network congestion and en­hanced network user capacity. More­over, by using a virtualised infrastructure, operators are able to reduce both their op­era­ting and capital expenses. While hardware costs are reduced by using shared servers rather than hosting dedicated app­liances, operational costs are reduced by having less equipment to maintain.

Global uptake of SDN and NFV

According to industry estimates, the global SDN market is expected to grow from $13.7 billion in 2020 to $32.7 billion by 2025 – a compound annual growth rate (CAGR) of 19 per cent. The adoption of SDN is expected to be driven by the enterprise segment, which is leveraging softwa­re-based solutions for network sharing,

ha­ndling big data generated from internet of things (IoT) devices and simplifying management tasks. Moreover, SDN is en­abling multiple service providers to utilise common network infrastructures whi­le ensuring isolation of network resources and strict confidentiality. Meanwhile, data centres have also started adopting SDN technology, as it helps in addressing co­ngestion-related issues and provides gl­obal visibility and control over the flows in a network.

The NFV market is expected to reach $122 billion by 2027, growing at a CAGR of 34.9 per cent between 2020 and 2027. The ever-increasing demand for automa­ti­on and the need for advanced network ma­nagement systems are some of the key factors driving the growth of the NFV market. This growth is also being aided by the rapid adoption of next-generation techno­logies, such as cloud computing and IoT. Going forward, favourable standards and networking regulations are also expected to drive the uptake of NFV solutions.

While Indian telecom operators initi­ally lagged behind their global peers with regard to the adoption of SDN and NFV, they have also started warming up to the id­ea of making their networks more software-based and virtual. At present, Bharti Airtel is using SDN/NFV to offer music and on-demand video services. Mean­whi­le, Relian­ce Jio Infocomm Limited has joi­ned the open network automation platform project as a platinum member to wo­rk with open source communities in order to build its own management and network orchestration software named Jio MANO, which is in pre-production, as well as to develop its own SDN controller. Vodafone Idea Li­­mited has also stated that it is running trials for SDN and NFV, and plans to deploy these technologies commercially soon.

Enabling role of SDN and NFV in 5G roll-out

SDN and NFV are poised to play key roles in the roll-out of 5G services because both these network architectures can help operators deliver a personalised customer ex­p­e­rience and achieve greater flexibility and control over their 5G networks. By supporting network slicing, SDN and NFV can help separate a single physical network into multiple virtual networks that share the same network infrastructure, thereby enabling operators to deliver services

bas­ed on each customer’s needs. Besides en­ha­n­cing the customisation capabilities of 5G, network slicing also helps operators deliver superior quality of service to customers by reducing latency and improving network security.

Moreover, the high flexibility and ad­aptability of SDN and NFV solutions will allow independent scaling and deployment of services to meet the throughput and processing requirements of different 5G services. SDN and NFV will also help operators scale up their operations to support 5G expansion, and configure their networks to allow seamless interaction between the different services inside the core network.

Catalyst in the adoption of next-generation technologies

Besides 5G, SDN and NFV are also playing pivotal roles in the adoption of next-generation technologies such as IoT, big data and cloud computing. This is because all these advanced technological solutions require a concomitant increase in network infrastructure to handle the data deluge that comes with their usage, thus necessitating huge investments by operators. Mo­r­e­over, with the emergence of new technologies, the hardware quickly beco­m­es obsolete, leading to huge recurring costs for operators.

To this end, SDN and NFV are helping operators make all their network elements programmable using a single standard user interface, thus enabling them to be controlled remotely from any of the chosen central locations. Moreover, using SDN and NFV, all network operations can be automated and the role of a certain network element can be easily changed by re­defining the network function of that element. This saves on the costs required for upgrading the infrastructure to handle the explosion of data that is currently being witnessed with the adoption of next-gene­ration solutions.

Issues and challenges

While telecom operators and enterprises, globally, are upbeat about the benefits that adopting SDN and NFV bring to their network operations, they have to grapple with the challenge of managing a combination of legacy networks and new virtualised networks until the migration to all-virtual networks is completed. Another key challenge is that operators cannot re­a­li­se the optimal value of SDN and NFV until the operations support systems and business support systems are aligned with the new technologies. Moreover, on the te­chnology front, a lack of mature techno­logy, consensus on multiple open source standardisation initiatives and proven business cases are also posing significant hurdles.

In some cases, virtualisation has also be­en reported to be leading to abnormal la­tency variations and significant throughput instability, even when the underlying network is only lightly utilised. Hence, en­su­ri­ng that network performance remains at le­a­st as competent as that of purpose-built hardware implementations also poses a major challenge. The transition to vir­tual net­works also raises security-related concerns. Software, by its very nature, is less se­cure than hardware. Moreover, un­like con­­ventional IT en­vironments, NFV re­quires the management of IT outside of an enterprise’s own premises, which rem­ov­es an element of controllability and raises security concerns.


The growing uptake of SDN and NFV is part of a larger trend of decoupling software from dedicated hardware, with a view to build agile networks at significantly lo­w­er costs. Their adoption also brings several other major benefits to operators and en­terprises, such as reduced time-to-market for new services, the ability to easily scale up operations, and the potential to offer personalised experiences to consumers and bring down the energy footprint of networks. However, going forward, the transition towards all-virtualised and software-based frameworks will be a long-drawn pro­­cess, as for most operators the shift wo­uld mean a complete dismantling of the ex­isting infrastructure to make way for new solutions. While such a migration may initially prove to be cost-intensive, in the long run, the adoption of SDN and NFV will yield significantly greater returns on in­ve­stments, along with a superior service quality experience for users.