They include established networking vendors, like Cisco Systems and Juniper Networks, companies coming over from the WAN optimization space, including Riverbed Technology and Silver Peak Systems along with pure-play companies such as VeloCloud, Talari Networks, CloudGenix, Aryaka, Glue Networks, Viptela and Nuage Networks. All are trying to carve out a place for themselves in a crowded market.
Gartner's Lerner said he expects more companies to get into the fray before the market starts to shake out over the next few years. One reason for the high vendor interest may be that Cisco, the world's top networking vendor, is not as dominant in the WAN as it is in the data center, he said.
"Maybe vendors view SD-WAN as a jump ball, and the value of incumbency is less advantageous," the analyst said. "A lot of vendors view this as a land grab."
That said, Cisco is making an aggressive push into the space and is using its network installed base to its advantage.
"Customers know they can trust and rely on us," Kiran Ghodgaonkar, senior marketing manager at Cisco, told eWEEK. "When we explain our SD-WAN solutions, they know they can work with us. … Customers want to make sure they're investing in the right solutions going forward. They're going to be investing [in the technology] for the next three to five years."
Verizon is an example of the strength of Cisco's broad customer base. The top-tier carrier is pushing a plan to virtualize its entire network, and in September 2015 announced it was adopting Cisco's iWAN (Intelligent WAN) SD-WAN suite of products as a key first step.
At the time, Shawn Hakl, vice president of enterprise networking and innovation at the carrier, told eWEEK that Verizon engineers had looked at other SD-WAN options, but went with Cisco because of Verizon's long working relationship with the networking vendor and because iWAN is the most prevalent technology in use in the enterprise and can easily scale.
Cisco launched iWAN about three years ago and now has more than 250 customers using the technology, Ghodgaonkar said. Officials also are looking outside the company. Earlier this year, Cisco was among the investors in a $27 million round of funding for VeloCloud, which helped bring the startup company's overall financing total to $49 million.
Cisco also wants to drive the conversation around SD-WAN. In September 2015, Cisco officials issued their "SD-WAN Bill of Rights," a list of 10 points they said network administrators can use as a guide to developing their SD-WAN strategies.
Despite the presence of Cisco, the expected rapid adoption of SD-WAN technology gives executives with smaller pure-play vendors confidence that they can gain traction in the crowded space.
VeloCloud's Wood said the company has more than 150 customers, with 40 of those coming to the company in the first quarter of the year, an indication of not only his company's momentum but also the interest in the space. "SD-WAN is the killer app of SDN," he said.
Talari Networks has been working the space for almost 10 years, deploying its first commercial product in 2008. That longevity is an asset to Talari, giving it a head start on rivals in building out its portfolio and incorporating feedback from customers, according to President and COO John Dickey.
"We were here before SD-WAN … was even a term," Dickey told eWEEK, pointing to the intelligence the company has put into its Thinking WAN overlay system. "That intelligent layer we have is pretty unique to us. Other players have it, but we're ahead of them."
Talari's portfolio includes eight physical and two virtual appliances as well as a network controller for orchestrating traffic between edge appliances and its Aware configuration, management and analytics platform. The portfolio promises everything from deep visibility into the WAN, traffic prioritization, bandwidth reservation, and secure and reliable access to cloud applications.