Cisco unveiled its own open protocol for software defined networking (SDN) that is alternative to OpenFlow, an already popular standard among SDN vendors.

The networking giant has convinced a number of major tech companies, including Citrix, Microsoft, IBM, Canonical, RedHat, Embrane and F5, to collaborate on and support the standard, called OpFlex.

Cisco's SDN technology that will use OpFlex is called Application Centric Infrastructure – the vendor's answer to competitors in the SDN space. The product Cisco offers as alternative to other SDN controllers is its Application Policy Infrastructure Controller (APIC).

Instead of sending specific configuration instructions to downstream networking gear, APIC sends down application policy, or the application's network requirements, allowing the devices to self-configure accordingly. OpFlex is the protocol and set of standards used to communicate that policy.

“Low-level” protocols, such as OpenFlow and OVSDB (Open vSwitch Database Management Protocol), are used in overlay SDN controllers. Michael Cohen, director of product management at Cisco, said this approach (alternative to Cisco's) merged policy and control plane in a centralized controller.

This controller becomes a bottleneck, creating issues of scale and resiliency, he explained.

Using a policy manager, Cisco's controller passes abstract policies to devices underneath, leaving the details of configuration steps for each specific device up to the devices themselves. OpFlex supports both physical and virtual switches.

“This approach is very different than the OpenFlow approach,” Cohen said. “It passes policy all the way down to the edges of the network.”

The protocol is designed to offer an open, standardized API (application programming interface) with an open source reference implementation.

Cisco is working together with Open Daylight, an SDN-focused open source development project under the Linux Foundation, to build an open source OpFlex agent for the Open Daylight controller. The code will be available on GitHub, the popular online repository for open source software.

An agent for Open vSwitch, an open source virtual switch, has already been created.

Cisco and partners have proposed OpFlex as an IETF standard. IETF (Internet Engineering Task Force) is a non-profit open standards organization that creates and promotes internet standards.