What is Over the Top (OTT) SD WAN?
3 MIN READ | SD-WAN

What is Over the TOP (OTT) SD-WAN?

Ricardo Belmar
Oct. 21 2019

If you’re shopping software-defined wide-area network (SD-WAN) solutions, you might come across the phrase “over the top,” or OTT. What is “over-the-top (OTT) SD WAN” and what does it mean? There are two ways to look at it:

  • Definition 1: An SD-WAN solution that runs over third-party network links (like the internet), versus “on-net” solutions that run over existing carrier-supplied WAN infrastructure.
  • Definition 2: An approach to implementing SD-WAN where you add new SD-WAN capabilities alongside existing carrier circuits.   

Definition 1 is far less interesting. After all, most companies considering SD-WAN already assume it will run over third-party circuits and the internet; that’s usually the point. Definition 2, however, gets to a question every business deploying SD-WAN should consider carefully: Should I rip out my existing WAN infrastructure and replace it with SD-WAN? Or, should I use SD-WAN to augment existing branch services?

OTT SD-WAN vs. rip-and-replace

There can be benefits to swapping out your entire branch network. You’ll end up with a new all-SD-WAN network at the end. Theoretically, you could see some upfront cost savings from replacing MPLS circuits with internet connections (eventually, at least). The big downside, however, is that rip-and-replace is a very long journey. For a large enterprise with hundreds of branches, it could take 12 to 18 months to swap out every site.

Alternatively, going over-the-top lets you add new functionality much more quickly. You just add new SD-WAN appliances to your existing branch architecture and start running new internet connections alongside what you have now. All of a sudden, you’re running a hybrid WAN—and benefiting from new SD-WAN capabilities in 2-3 months, instead of a year or more.

OTT SD-WAN Benefits

When you go OTT, your upfront connectivity costs don’t go down as they might with a rip-and-replace; you’re adding service, after all, not removing it. But you’ll see value in many other areas:

  • Painless transition: You don’t have to deal with the ongoing disruptions and downtime that typically come with a rip and replace—disruptions that definitely carry a cost.
  • Faster time-to-value: The benefits that caused you to consider SD-WAN in the first place—like improved performance for cloud applications and ability to route application traffic over the best possible connection—can now be realized at all sites right away, instead of one-by-one over many months.
  • Faster application onboarding: If you’re looking to SD-WAN to give you more capacity and performance for a new application, the OTT approach gives you more total bandwidth immediately. Especially for delay-sensitive applications like video or collaboration, expect to onboard more users more quickly. You’re far less likely to run into problems than when you’re turning infrastructure up and down at different sites at different times.
  • Less complexity and risk: It may seem counterintuitive that using OTT SD-WAN and legacy WAN side-by-side would make things simpler. But think about what it means when you switch from one to the other. If you’re moving from carrier MPLS to third-party SD-WAN, during the entire transition (again, 12-18 months), you have to carefully coordinate the shutdown of old services and bringing up new ones with two providers at every site. With OTT SD-WAN, you’re just adding new service, not risking any downtime at all.

Does OTT SD-WAN make sense for your business?

Rip-and-replace appeals to some organizations who want a total WAN overhaul. But for larger organizations that depend on branch sites for revenues, a more cautious approach is usually the better choice. It all comes down to what you want from your SD-WAN.

If you’re looking for better application performance, more control, extra capacity, and a better user experience at branches, you’ll see all those benefits much more quickly with OTT SD-WAN. And, if you choose to flip the switch to full SD-WAN in the future, it’s easier and less risky, because all sites already have it in place.

Just make sure you’re using an SD-WAN solution built for over-the-top operation. Many SD-WAN solutions are designed with the assumption of rip-and-replace—even though that’s not what most enterprises actually want. If your goal is to go hybrid—and to get there as quickly and painlessly as possible—choose an SD-WAN designed to run OTT just as effectively as in standalone deployments.

Find out how you could reduce WAN expenses by up to 40% and create a cloud-ready WAN. Learn more about how Infovista has been cited as a "Sample Vendor" for hybrid WAN in Gartner's Hype Cycle.

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