Who says software-defined wide-area networking (SD-WAN) is just for startups? Adara and Calient, two non-startups with heritages that date back to the late 90s, are tackling this market by combining their software stack and optical switch, respectively.

It's a different take on SD-WAN, a technology that offers customers the promise of flipping among multiple WAN choices for different types of traffic. The field is stuffed with startups, most of them bearing packet-network expertise.

Calient's realm is the optical network. For more than a decade, the company has been selling photonic switches — devices that forward a fiber-optic signal without translating the traffic into electrical form. Calient handles traffic according to wavelengths rather than packets.

One benefit of optical switching is lower latency compared with packet switching. So one possible advantage of this setup is the addition of low-latency optical overlay networks to an enterprise's SD-WAN options. The companies also mention the possibility of including trans-oceanic links as SD-WAN options.

Adara, meanwhile, is providing the "SD" piece of SD-WAN in the form of its software-defined networking (SDN) stack. The company has a long history selling software stacks, and in recent years it's turned that expertise toward the SDN and network functions virtualization (NFV) markets.

The SD-WAN market is bubbling with activity after becoming hot in 2015. Recent moves include Cisco joining VeloCloud's funding round and the acquisition of Pertino by Boise, Idaho-based Cradlepoint.