Cisco today indicated it is collaborating with Microsoft to bring more openness to its data center switching.

Cisco will help Microsoft’s Azure Cloud networking by adapting its NX operating system (NX-OS) for its 9500 modular data center switches. And Cisco will support the open source switch abstraction interface (SAI) on its 9200 and 9300 Nexus fixed data center switches.

“Cisco and Microsoft have collaborated on adapting Cisco’s NX-OS on Nexus 9500 switches,” wrote David Goeckeler, the general manager of Cisco's networking and security business, in a blog post this morning.

In terms of “adapting” NX-OS on 9500 switches, Thomas Scheibe, a Cisco product marketing director, told SDxCentral that will include helping Microsoft, as well as other big cloud providers, upgrade the software and routing features with “the kind of engineering that helps them build more reliable, easy-to-operate infrastructure.”

“In addition, Cisco’s Nexus 9200/9300 platforms running Cisco’s Switch Abstraction Interface (SAI) will offer customers the freedom to run the network operating system of their choice on SAI-ready Cisco Nexus platforms,” wrote Goeckeler.

SAI allows software to program multiple switch chips without any changes. It is a standardized API to program network switch ASICs. SAI was actually written by Microsoft, which then turned it over to the Open Compute Project (OCP), making the code available to everyone.

Scheibe explained that Cisco’s SAI is specific to its ASICs. “We’re adhering to an open interface implementation,” he said. “We sell our own switches with our own ASICs and our own operating system. But for fixed, we’re making the option available to have an SAI layer on top so you can run their OS on top of those fixed switches.”

In Microsoft’s case, “their OS” would be the Software for Open Networking in the Cloud (SONiC).

Microsoft has complained that it’s difficult to run different software operating systems on different switch hardware platforms and integrate it all into a cloud-wide network management platform.

To help with this integration, Microsoft created SONiC, an open source software to run cloud switches. SONiC allows cloud operators to share the same software stack across multiple switch vendors’ hardware. And Microsoft turned its SONiC code over to the Open Compute Project in 2016.

An important aspect of SONiC is that it can run on various switching platforms via the SAI specification, which was also created by Microsoft and was accepted by OCP in July 2015.

In today’s Goeckeler blog posting Yousef Khalidi, corporate VP of Microsoft Azure Networking said, “Cisco support for the SAI abstraction layer on its Nexus CloudScale switches helps fulfill our vision for SAI to enable rapid innovation in silicon, CPU, power, port density, optics, and speed across multiple platforms while enabling Microsoft and cloud operators to leverage the same software stack across a variety of switch hardware platforms.”

Cisco joins several other switch makers that are already working with Microsoft, including Arista, Dell, Edgecore, Ingrasys, and Mellanox.