What is SD-WAN and What It Is Not


Just a couple of years ago at the annual Interop Expo, Software Defined Networking was barely discussed or promoted. Fast forward to 2019, and there are mentions of SD-WAN in nearly every session and presentation. The SD-WAN term has picked up momentum and is almost a marketing term thrown around like Cloud or UC. Just like the term cloud is loosely defined, SD-WAN has likewise started sharing the same unfortunate clarity.

When we talk about SDN or SD-WAN, there are a few minimum requirements to qualify for the term.

•  It is a network service or an overlay that is going to replace what is a more traditional type WAN service like an MPLS service. Meaning a private network provided to a person from a networking provider.

•  This solution is provisioned, and you interact with it in some portal, or it could be cloud driven.

•  Automatic failover. If you plug in two connections, it needs to fail-over to the other.

With these three common denominators to define SDN, you can wash out all those tricky claims many people are making about their “SDN solutions” and focus on the real solutions. It’s a hot and trendy term, so following this definition will save you a lot of frustration of wasting time with solution offers that are somewhat counterfeit or misleading.


The providers that are offering legitimate SDN solutions can provide a crucial feature as it relates to performance. For example, let’s examine a scenario where you have your two internet connections. There is an application like hosted VoIP and a low-cost bandwidth solution like cable backed up with a DSL connection. Neither of those connections is bulletproof. A key feature functionality is the ability to adapt to the performance of the environment in real time. Look at latency with the cable and DSL along with jitter and packet loss as all three affect the voice quality. Good SDN solutions will be able to take those into account in real time and adapt a voice call as it relates to the real-time performance of the network. When problematic connections arise, it could reroute to the secondary link without disrupting the call. All that without having to touch the box since it’s automated.

In a traditional router environment, you can load-balance two connections as well as automatic failover. But typically, you will do that based upon hard downs. That will require manual swapping and restarting connections which cause interruptions. SD-WAN does all that without any perceived disruptions or manual servicing.

A bonus feature is the ability to alert. Set notifications to alert about an outage and gain visibility on who is doing what within your network environment.


Case Study #1

In this example, the customer has the following environment:

•  Retail Store Chain

•  Hundreds of branches

•  Hosted VoIP customer

•  Private cloud (everything remote to branch)

•  Dual provider MPLS T-1 based WAN (failover)

The problems this customer faces are:

•  Bandwidth starvation

•  New applications

•  Remain PCI compliant

•  Retain similar cost structure

In the T-1 world, the only real other option is to add another T-1 which may be an additional $250 per month. Now take a look at the alternative, let’s say you grab a fiber connection with 100 megs. You have the opportunity to get some lower cost bandwidth, and then back it up with a 25 meg / 4G solution and have the 100 meg SDN overlay. They’ll have the new ability to run their new applications and even save a little bit of money.

Case Study #2

In this example, Telarus offers its experience with switching to SDN. Our situation presented as:

•  Technology Company

•  170 employees

•  Hosted VoIP customer

•  Fairly heavy SaaS users for production platforms

•  Office 365 customer

•  Few internal servers hosting applications

The hosted VoIP solution is key to our environment. We had a 100 meg coax and a 100 meg fiber connection with fiber being primary. With testing the SDN solution, we experienced a bunch of outages lasting about an hour or two each. Most employees, had no idea since the automatic fail-over kicked in. Doing the math, an hour of downtime for us is about $3,500 per month. Within eight business days, there were eight of those outages which would have been about a $20,000 productivity loss. Thus, auto fail-over is a crucial piece. The reduced downtime will result in the service paying for itself in a year.

To learn more about SD-WAN and Which One is Right for Your Business

Email mchapman@go2communications.com or Schedule a Call: https://calendly.com/michael_chapman