SDN vs. SD-WAN: A Buyer's Guide

By Ray Watson, VP of Global Technology, Masergy

Ray Watson, VP of Global Technology, Masergy

Based on naming conventions alone Software Defined Networks (SDN) and Software Defined Wide Area Networks (SD-WAN) are easily confused. You’d be forgiven for assuming they are one and the same. Both are relatively new technologies, both transform networks and the enterprise. However, there are significant differences in how these modern innovations can help.

SD-WAN and SDN closely resemble each other; both are relatively new innovations; and market watchers are right to be excited by both. IDC says the SDN market will have a compound annual growth rate (CAGR) of 53.9 percent from 2014 to 2020 and SD-WAN will grow at a more than 90 percent CAGR for the next five years to become a $6 billion industry by 2020. Both technologies are worth watching.

SD-WAN is a rapidly emerging technology that complements existing enterprise network architectures, enabling companies to implement highly ‘elastic connections’ to branch offices and remote locations using commercial broadband services and MPSL. It also differs from other network technologies in its ability to provide application-based, rather than packet-based routing, which gives IT departments greater control over quality of service for users. It promises much – application reporting, zero-touch provisioning, centralised policy management and policy-based application routing.

There are some issues you need to consider when thinking of adopting SD-WAN solutions. There are performanceissues associated with many of the capabilities that SD-WAN uses to make the Internet more reliable. Upload speeds may also be constrained when using SD-WAN purely over broadband Internet. And while many believe SD-WAN is less expensive than private networking, in some cases, it is not. Setup and maintenance of centralised policy management and zero touch provisioning can be complicated and resource intensive.

It’s also worth pointing out that vendor hardware/software solutions are proprietary and the market lacks interoperability standards, which can cause vendor lock-in. SD-WAN solutions are increasingly being offered by managed service providers that can help mitigate the risks of vendor lock in and the complexity of a do-it-yourself implementation.

Software Defined Networks

SDN makes networks more agile and flexible and enables network administrators to use software to orchestrate configuration and change management tasks that are typically performed by administrators on a device-by-device basis.

SDN is a work in progress. Enterprises are mulling over the best way to make it work for them. According to Ashton, Metzler & Associates, 75 per cent of enterprises are evaluating SDN in concept, in a lab or limited trial, and 25 per cent of enterprises are running SDN WANs in a lab, limited trial or production environment.

While some standards already exist, a maturation process is needed to improve the technology for customers. SDN also requires networking staff to switch their focus and skills from a hardware- to software-centricity. With SDN, IT staff configure networks with graphical software and write code using interactive developer tools. This requires new ways of thinking, new types of training, perhaps even new positions on the IT org chart.

While SDN’s business benefits are real, they can be difficult to demonstrate at this point. SDN involves foundational architectural changes, so the benefits can take time to appear. Small, quick implementations can be a powerful way to demonstrate these benefits — and to obtain additional funding for future projects.

My advice to organizations is to work with knowledgeable subject matter experts to map out how SDN can be integrated into network designs, processes and competencies.

In summary, the main differences between both technologies is that SD-WAN focuses on application routing capabilities for Wide Area Networks, connecting geographically distributed offices. SDN is primarily focused on designing more dynamic and responsive networks that can respond to changing computing models and business demands.SDN and SD-WAN are complementary. Many enterprises and service provider networks have implemented SD-WAN atop their SDN-enabled networks.

Ray Watson is VP of Global Technology at Masergy. He brings over 17 years of expertise in IT strategy, application solution design and next-generation network architectures. Ray has enabled numerous global enterprises in transforming their IT infrastructures to guarantee business outcomes. Ray is an industry thought leader in IT transformation and is a frequent speaker on topics such as hybrid networking, SDN, NFV, cloud connectivity and advanced security. Prior to joining Masergy, Ray worked at Airband Communications and Broadwing Communications. He holds a B.S. from Purdue University.