Since it's inception, SD-WAN has sought to address problems like bandwidth constraints, security, and the high cost of MPLS across the WAN. However, the adoption of SD-WAN hasn't been without growing pains.

At this week's now virtualized WAN summit, executives from Orange Business Services, Nuage Networks, and Riverbed discussed the realities faced by enterprises and offered their advice and predictions for the future of SD-WAN.

SD-WAN opens to the door to levels of visibility previously impossible by traditional means, said John Isch, director of the network and voice center of excellence at Orange Business Services.

"In the past, we thought about networks as round trip delay, packet loss ratio, and jitter and then ... we calculated what the impact would be to an app," he said. "Now we actually have visibility into what's happening with individual applications and how they operate in the network."

While great in terms of visibility, Isch says this poses a challenge for service operations teams not prepared for this level of detail.

And this change in philosophy extends well beyond service operations teams to security, applications, and networking teams, said Riverbed's Deputy CTO Michael Kaehly.

"We're seeing disparate use cases and requirements that I think SD-WAN is able to address, but from a buying perspective it's proving to be a little more complicated," he said, explaining that vendors now have the challenge of identifying which team within the enterprise will actually make the final decision.

Speaking on SD-WAN rollouts, Nuage Networks Head of Marking Lindsay Newell said one of the biggest challenges larger enterprises are facing when adopting an SD-WAN platform today is inertia. He explained it's a rarely a clean switch for these kinds of businesses.

"If you're doing a 10 site, local SD-WAN that's pure internet underlay, you can probably do a flash cutover," he explained. "If you're doing 1,000 site, multinational deployment with multi-cloud integration then you're going to operate in a hybrid environment while that SD-WAN is being rolled out, and that process may take a year or even two years."

Enterprises should think of SD-WAN as more than a replacement for the WAN, said Isch, adding that they should also consider the opportunities to transform their LAN infrastructure as well.

Building on Isch's point, Kaehly said enterprises should also understand that there are some challenges that are never going to get easier. "The routing infrastructure, complexities in the brownfield environment are always going to be there whether they're moving to an SD-WAN service or your shifting carriers for a global MPLS," he said.

For a successful SD-WAN deployment, Isch recommends a three-step strategy involving a proof of concept, a pilot deployment, and then to use those two to inform a full-scale deployment. "Going through anything of this size or this complexity you're going to learn things," he said.

Further, Kaehly says enterprises need to have a way to validate that their chosen SD-WAN solution actually addresses their particular use case.

Looking to the future, Newell expects security and cloud integration to become increasingly important for vendors looking to differentiate themselves.

Touching on that issue, Isch added that SD-WAN will soon be only a small part of a larger offering.

"These SD-WAN solutions are not going to remain standalone solutions," he said. They are going to become part of an overarching cloud, LAN, and WAN service.

Both Newell and Kaehly agreed that despite the SD-WAN's advantages, MPLS wasn't going anywhere.

Newell explained that one of the biggest considerations is that many enterprises are tied to existing MPLS contracts that necessitate a transitional hybrid deployment using both technologies.

However, Kaehly argued that service providers have not been placed under sufficient pressure to reduce MPLS pricing. 

"I think we can all agree pricing is the No. 1 driving factor in terms of SD-WAN adoption," he said, adding the fact that migrating to another environment, whether it be DIA or an SD-WAN, is still a painful process if it involves migrating ports.