Broadcom isn't quite "opening up" its switch chips for the industry, but it's taking a close step — giving developers access to otherwise proprietary APIs.

The vendor, which enjoys a dominant market share in Ethernet switch chips, announced the idea of the Open Network Switch Library (OpenNSL) a year ago. Today, at the Open Compute Summit in San Jose, Calif., Broadcom is releasing the first set of APIs in the library.

It's a small set, including APIs that can support Facebook's FBOSS operating system and Microsoft's Switch Abstraction Interface (SAI). Broadcom has produced reference implementations for those two items — implementations that might not be ready for production use but still give developers something to work with, says says Eli Karpilovski, director of product management for Broadcom's network switch group.

White box switch vendors at the Summit will be showing their hardware running applications built with OpenNSL, Karpilovski says.

OpenNSL also includes support for Broadview, Broadcom's network visibility capability that was announced with the Tomahawk chip family in September.

It's a small start, but what counts is that the Open Compute Project (OCP) is getting wider latitude to create open source software specifically for Broadcom's chips.

Developers previously couldn't get access to the Broadcom SDK without a nondisclosure agreement. The NDA wouldn't necessarily cost money — Broadcom shared frequently with academic institutions, for instance — but it was necessary because the SDK offered too deep of a view into Broadcom's chips, giving away intellectual property, Karpilovski says.

But an NDA would run counter to the spirit of OCP, which was started by Facebook in hopes of producing open source hardware designs. So Broadcom is using the OpenNSL APIs as a way to allow access to the chip's software while blocking that view into the hardware. The APIs map Broadcom's SDK calls to a new interface that doesn't require a license.

"Think of the OpenNSL APIs as the SDK APIs but with a different interface," Karpilovski says. They're a tool for anyone wanting to develop open applications, even an open operating system, to run on Broadom's switch chips.

It does not mean Broadcom is open-sourcing its chip software Karpilovski stresses.

Startup Centec has opted to make its SDK available on an open source basis, but Centec is a relatively new player with less of a franchise at stake than Broadcom has. "Some of the smaller companies that are opening up, it's because there's nothing as valuable there, and they're hoping the ecosystem can build them up," Karpilovski says.