Evaluating SD-WAN Technologies

Software-defined WAN is hot. Here are some key considerations before making a purchase.

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Evaluating next-generation network infrastructure technologies, including software-defined WAN, can be a difficult process. One must wade through the marketing rhetoric to find meaningful factors that differentiate various solutions. Most SD-WAN products available today offer simplified management, intelligent routing, and added security. But it’s up to you to figure out which product most closely aligns with your specific needs.

What to look for

While there are a lot of similarities among SD-WAN products, there also are important differences. For example, all SD-WAN vendors use a network overlay architecture to create the logical mesh for software-defined data transport and control plane communication. Some vendors' architectures call for the creation of simple point-to-point VPN tunnels between all sites that form a static mesh. Others use a more flexible approach by implementing Dynamic Multipoint VPN (DMVPN) hub-and-spoke technologies. So depending on your current and future WAN needs, one approach may be more suitable than the other.

Another potential difference between vendors is weighing the benefits of customization against the ability to execute simplified deployments. Some vendors give network administrators granular control of every aspect of the SD-WAN configuration. By doing so, trained technicians can make the necessary adjustments to squeeze out additional performance. Other vendors tout ease of deployment as their differentiating factor; some even go so far as to offer a zero-touch provisioning deployment option that is literally plug-and-play.



When evaluating SD-WAN vendors, it’s important to always be aware of how an SD-WAN can add value compared to the current WAN architecture you are managing today. If you struggle with WAN scaling issues, identify SD-WAN vendors that allow for low-cost expansion with little added complexity. Also, be sure to consider your infrastructure implementation options. While most SD-WAN vendors offer virtualized options for SD-WAN components, not all provide hardware appliances for every SD-WAN function on the network. Others offer some limited hardware options.

SD-WAN use cases

Designing and implementing an SD-WAN is a fairly complex and expensive endeavor. That’s why it’s important to understand situations where it makes sense to implement an SD-WAN today versus holding off for a few more years. For some, the pain points in the WAN are significant enough to justify the time and money spent to deploy a comprehensive SD-WAN. For others, it may be better to wait until the SD-WAN market matures a bit more. After all, Gartner reported late last year that less than 1% of enterprises have actually implemented an SD-WAN solution, but by 2019 Gartner predicts a 30% implementation base.

One scenario where it would make sense to deploy an SD-WAN is when you are encountering increasing leased-line expenses. If you find yourself with a large number of carrier circuit contracts that must be renewed, and those costs are significantly higher than expected, leveraging intelligent routing over low-cost broadband connections is highly appealing. And the larger your WAN is, the bigger the cost savings.

Another scenario that justifies the build-out of an SD-WAN architecture is if your organization requires rapid deployments across a large geographical region. The beauty of most SD-WAN products is that the core intelligence is controlled and managed centrally. This means that remote site deployments can be as simple as plugging in an SD-WAN router and connecting it to one or more WAN circuits. Additionally, because SD-WAN can intelligently leverage standard Internet connections that are installed within days, WAN deployment times can be significantly decreased.

Finally, SD-WAN deployments make sense when your WAN is complex from a policy perspective. The decoupling of control information across the entire WAN plays a key role in this scenario. Centralizing control means that whether you need to identify, mark and enforce QoS policies for specific application traffic -- or if you need to apply granular security controls across the entire WAN – a centralized SD-WAN streamlines end-to-end policy enforcement. And when policies need to be added or adjusted, they can be configured and pushed out to the entire WAN simultaneously.

It’s easy to see why SD-WAN technologies are so hot right now. Whether you struggle with increasing costs, difficulty in management, or simply need a more flexible and scalable WAN, SD-WAN can help solve those problems. But at the same time, SD-WAN technologies, features, and benefits vary from one vendor to the next. Because of this, it’s critical that you understand what capabilities matter to you most and find the vendor that provides the biggest bang for your buck.

About the Author(s)

Andrew Froehlich, President, West Gate Networks

President, West Gate Networks

As a highly experienced network architect and trusted IT consultant with worldwide contacts, particularly in the United States and Southeast Asia, Andrew Froehlich has nearly two decades of experience and possesses multiple industry certifications in the field of enterprise networking. Froehlich has participated in the design and maintenance of networks for State Farm Insurance, United Airlines, Chicago-area schools and the University of Chicago Medical Center. He is the founder and president of Loveland, Colo.-based West Gate Networks, which specializes in enterprise network architectures and data center build outs. The author of two Cisco certification study guides published by Sybex, he is a regular contributor to multiple enterprise IT related websites and trade journals with insights into rapidly changing developments in the IT industry.

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