It may have only been commercially available for a couple years, but the ability of software-defined wide area networks (SD-WAN) to address enterprise networking needs has led to remarkable growth, according to analysts at market research firm IDC.

In fact, IDC has estimated that global SD-WAN infrastructure and services revenues will see a compound annual growth rate (CAGR) of 69.6%, reaching $8.05 billion in 2021.

Digital transformation (DX), in which enterprises will deploy 3rd Platform technologies such as cloud, big data and analytics as well as mobility and social business, will drive SD-WAN growth over the next five years. DX generally increases network workloads and elevates the network's end-to-end importance to business operations.

Another factor driving the growth of SD-WAN is the continued rise of public cloud-based software-as-a-service (SaaS) applications, according to IDC. The increase in SaaS adoption for business applications throughout the enterprise disrupts the prominence of MPLS-based WAN connectivity to the branch. SD-WAN is increasingly leveraged to provide dynamic connectivity optimisation and path selection in a policy-driven, centrally manageable distributed network architecture.

Finally, the growth in SD-WAN will benefit from the broader acceptance, and adoption, of software-defined networking (SDN) throughout the enterprise. As virtualisation, cloud management and SDN continue to gain traction throughout enterprise networks, SD-WAN will benefit from this paradigm shift and receive increasing consideration.

"SD-WAN is not a solution in search of a problem," said Rohit Mehra, vice president, Network Infrastructure at IDC. "Traditional WANs were not architected for the cloud and are also poorly suited to the security requirements associated with distributed and cloud-based applications. And, while hybrid WAN emerged to meet some of these next-generation connectivity challenges, SD-WAN builds on hybrid WAN to offer a more complete solution."

SD-WAN leverages hybrid WAN, but includes a centralised, application-based policy controller; analytics for application and network visibility; a secure software overlay that abstracts the underlying networks; and an optional SD-WAN forwarder (routing capability). Together these technologies provide intelligent path selection across WAN links, based on the application policies defined on the controller.

The benefits of SD-WAN include cost-effective delivery of business applications, meeting the evolving operational requirements of the modern branch/remote site, optimising software-as-a-service (SaaS) and cloud-based services such as UC&C, and improving branch-IT efficiency through automation.