Programmable hardware startup Corsa Technology has raised a $16.5 million Series B round to pursue its FPGA-based data plane.

The funding, announced today, was led by Roadmap Capital and involved all previous investors, including Celtic House Venture Partners, BDC Ventures, and one tech company that isn't being named. Ottawa-based Corsa, founded in 2013, has raised $22.6 million all told.

Corsa's DP6400 is a chameleon system that the company calls a programmable data plane, targeting the wide-area network (WAN). Based on FPGAs — chips whose hardware can be reprogrammed — the DP6400 could be tailored to suit any type of control plane. Corsa started out by pitching the box as an OpenFlow switch, but it's also able to become a router or a Layer 4-7 box.

For the moment, though, customers are interested less in any software-defined networking (SDN) capabilities and more in the DP6400 just being a box.

"The No. 1 thing is actually not even an SDN feature. It's that we built hardware that really is WAN-scale," says Bruce Gregory, Corsa's CEO.

What customers have liked is that the DP6400 is customizable. They can ask Corsa to add only the features they want and ignore any others — something they can't do with an ordinary switch or router. During the last 18 months, Corsa has been working on creating some of these features.

FPGAs always come with a tradeoff. They take up more space than customized chips, and the price and power consumption don't always compare favorably either. So far, that hasn't been a problem for Corsa, because in the WAN, it's competing with systems that are expensive in the first place.

"At some point, it'll come. As we scale up bigger and bigger, we'll have to come up with a more creative solution," Gregory says.

Corsa hasn't named any customers yet beyond ESnet, which is using the gear as a high-end router for a research-network backbone. The company has also drawn interest from enterprises for SDN-related uses, Gregory says.