The benefits of an open market may sound worthwhile — flexibility, speed, cost-saving, freedom, scalability, neutrality — but there are certain corners of the greater technology and software industry where openness has not quite reached, including SD-WAN.

In recent months it seems that there are certainly components, use case, and even companies — flexiWAN joined the market in April with plans to build an open architecture for SD-WAN — arising as examples for open SD-WANs, but open source has yet to be adopted fully into the networking technology.

And though in some ways it seems that open source is right around the corner, it could be further away than expected. There is even some debate as to whether SD-WAN needs open source, but it’s worth discussing how openness could help the technology.

Does SD-WAN Need Open Source?

“Needs? No," said Mike Fratto, senior analyst at 451 Research, when asked is SD-WAN needs open source. "However, companies that are comfortable bootstrapping software themselves like MSPs [managed service providers] and integrators can achieve a significant cost savings in licensing if they can use open source and, this is the important part, cost effectively build a service around it. It’s a significant investment but can pay off after the work is done.”

For Ariel Dan, CEO of Cloudify, there are a number of SD-WAN challenge areas that openness could help. These include the lack of consistency between the sheer volume of options; that a number of SD-WANs don’t allow for integration with other network components; the lack of automated management for SD-WAN; vendor lock-in; and high-bandwidth overhead. Cloudify is working on open orchestration that will help grow SD-WAN toward a more open future.

Amir Zmora, the CEO and co-founder of flexiWAN, said that an open SD-WAN architecture would help IT managers gain control over their network components and allow service providers to prioritize and optimize an enterprise’s network for each use case. “I think this is a revolution to the SD-WAN,” said Zmora. “It happens to be open source, but the big thing is the revolution on breaking the monopoly there — Open source really opens the door for democratizing this market.”

Some of these challenges suggest that SD-WAN needs a shake-up — “I think feature wise the SD-WAN segment has stalled,” Fratto said. “Open source projects may jump start it again if for only generating new ideas for features and capabilities.”

Frank Cittadino, CEO of managed network service provider QOS Networks, told SDxCentral that “open source is going to be probably the last uptick in SD-WAN because it does run such critical infrastructure at this point and the dominant buying method of these larger customers are from large manufacturers: Cisco, VMware, and a couple others.”

And while Cittandino sees these vendor-centric solutions dominating for a while, this will change in the next three to five years as open source becomes more mainstream and as vendor roadmaps slow down and “become more about selling products within those platforms.”

However, it could be too soon for open source with many vendors leveraging their technology in order to survive the crowded market. And open source could even dis-incentivize innovation to an extent.

Though SD-WAN startup Bigleaf Networks is contributing to open source initiatives and even leveraging components (more on that later) in its technology, CEO Joel Mulkey noted that “I don't see a fully open-source SD-WAN platform on the horizon for the industry right now. Our proprietary technology is a major technical differentiator for us. If we were to release it to all for their own use that could pose a competitive risk. Plus making it open source could slow down our aggressive pace of innovation.”

But whether it’s open source that will drive this innovation has yet to be determined. Many suggest that standards should probably come first. “The community needs to come to an agreement on design, architecture, [and] APIs before open source SD-WAN can happen,” said Steve Woo, senior director of product management at VMware's VeloCloud business unit.

Standards First

There are around 60 SD-WAN vendors in the market, and the solutions range from full-featured, to added-features, to just basic features. Woo explained that this has made it hard to develop a common definition and standard due to the sheer number of stakeholders.

Dave Ginsburg, VP of product and solutions marketing at Aryaka, mirrored this statement saying that the market is still too early for open source, mainly because “there is no real standardization in place … the overall SD-WAN experience is more important than any open source discussion.”

“Open source components in the networking area typically happen for more mature technologies where standards and/or well-defined multi-vendor architectures are in place," Ginsburg said. "There is therefore not much demand, at this point, for interoperability between SD-WAN providers."

But standards might be close. MEF is currently working on a SD-WAN standard that includes a number of service definitions and attributes. The group has been working on an SD-WAN standardization since at least 2017, and last October created a technical specification to define SD-WAN services and their attributes, which is expected to publish soon.

What’s possible is that these definitions could help drive open source, but it won’t happen the other way around.

"Enterprises and service providers can build things with open source, but open source is just the tool kit of all the bits and pieces," said Charles Eckel, application committee co-chair at MEF and developer advocate of open source and standards at Cisco. "The service definition is what ties it all together from something that someone wants to buy because people don’t want to buy bits and pieces they want to buy the whole packaged thing and it allows to have a common definition."

Having standards, Eckel added, will allow managed and communications service providers to more quickly roll out and design SD-WAN services and customers will know, based on certification, that they will deliver what is promised.

What Exists: Components

Yet, before the standard, open source has started to infiltrate the technology as a number of vendors are currently using open source components — mainly orchestrators and security features — in their SD-WAN services.

"There's not really an open source approach right now," said Roy Chua, founder and principal analyst at AvidThink. "There are open-source pieces out there for VPN, FW, IDS (all the security elements), routing, and perhaps LF Networking DANOS will emerge as a viable platform on which to build uCPEs, but we haven't seen anyone try to pull a solution together yet."

Phil Robb, VP of networking and orchestration at the Linux Foundation, said the group has three projects that intersect with and help the SD-WAN market: ONAP, OpenDaylight, and the Tungsten Fabric.

“ONAP can act as a global orchestrator for NFV/SDN services that include an SD-WAN component. … OpenDaylight and Tungsten Fabric support EVPN [Ethernet VPN], which enables the connectivity of dispersed customer sites by using a Layer 2 virtual bridge. This feature can be used to connect a branch to a WAN edge in a secure manner,” said Robb. He added that OpenDaylight can also be used as a WAN orchestrator.

Network automation firm UBique developed its MS Activator to "help drive easy and affordable integration and to drive greater automation," according to company CEO Nabil Souli. The company later open sourced the orchestrator under the name OpenMSA, "which acts as an orchestration framework."

Among the many use cases of OpenMSA is SD-WAN. NEC, which is one of the members of OpenMSA, recently deployed an open SD-WAN and Security Platform at the University of Kuala Lumpur in Malaysia that was based on the OpenMSA architecture.

"The SD-WAN that [NEC’s] pitching has nothing to do with Versa Networks or VeloCloud or none of the big shots in the U.S., it’s virtually them building their own SD-WAN for the university," Souli said. NEC did so by stitching together the parts that create the SD-WAN — including security features — by developing the MS Activator technology for the use case, he added.

Cloudify has also begun building an open virtual CPE (vCPE) and SD-WAN platform that will provide an automated way to access a number of SD-WAN use cases through its orchestration.

What Exists With SD-WAN Vendors

Though many of the SD-WAN vendors themselves are not quite ready for open source, they are contributing or benefiting in some ways.

Mulkey said that Bigleaf has "used many open source components from day one to build the Bigleaf platform." The provider uses Linux as its operating system, Graphite for time series data storage, and used a number of open source tools — Bazel, Vagrant, and Puppet to create and manage its core SD-WAN monitoring and adaptation software.

"As a high-growth company we need to be nimble, and popular open-source tools enable that by having good design principles built-in," Mulkey added. "If we didn't have such a thriving open-source ecosystem, I doubt Bigleaf and many other similar tech companies would exist. So yes, SD-WAN needs open source, and as the industry matures we need to ensure that we're contributing back to the community. I don't think though that this will include the core software that most SD-WAN players have built out.”

Aryaka has also used some open source components in its managed SD-WAN offering, said Ginsburg, adding that this is the case for "practically every other vendor." He noted that for some, a do-it-yourself model is emerging where customers can select their components — connectivity, security, optimization — and are responsible for integration, in which case some of the aforementioned open orchestrators and integrators could help.

VeloCloud, similarly, uses what Woo referred to as "open source software that is peripheral to SD-WAN itself." This includes the tools for data plane interfacing and routing systems external to VMware SD-WAN such as Linux, SQL, Python, and Quagga. Woo added that VMware-VeloCloud developers participate in a number of open source projects and forums including MEF and ONUG.

"VMware is heavily investing in SD-WAN innovations that will not become available from the open source community until the broader development community matures over many years," said Woo.

According to flexiWAN's Zmore, the company intends to build an open architecture that allows for the integration of third-party elements into the core of the SD-WAN edge device.

Many other vendors and providers also use or used open source components to build their proprietary technologies, which speaks to the growing pervasiveness of open source as a whole. Perhaps it’s only a matter of time before vendors begin to contribute back into these communities and a fully-open SD-WAN code or architecture will emerge.