In a move that demonstrates the growing urgency for traditional networking technology vendors to adopt open approaches to Software Defined Networking (SDN), Extreme Networks (EXTR) has joined the Opendaylight (ODL), joining Oracle and Flextronics as recent additions to the movement.

Extreme Networks said that it will develop its own SDN controller based on open standards. Oracle announced on June 5 that it will join ODL and integrate the open source platform into its Solaris operating system. Oracle said the goal is to more easily build SDN applications into its software. 

SDN is a collection of open, networking control software, including ODL and other standards such as OpenFlow. The goal of SDN is to put make networking more powerful and interoperable by putting more software options into the hands of customers, who could integrate open-source software with proprietary networking hardware platforms. ODL is a collaborative open source platform to develop control software and APIs for networking based on the OpenFlow protocol

The most recent additions show building momentum for the SDN movement. Oracle and Extreme are big names that were missing from the ODL roster. Most big networking players, including Brocade (BRCD), Cisco Systems (CSCO), Citrix CTXS, Ericsson, HP (HPQ), IBM (IBM), Juniper (JNPR), and Microsoft (MSFT) have been members for quite a while. One of the largest and most stubborn holdouts among the networking players, HP, joined ODL last month. Cisco, in contrast, was relatively early and was one of the first networking companies to ship and OpenDaylight-based controller.

Extreme executives, in an interview with the Rayno Report on Monday, touted the need to provide its customers with a flexible path to SDN, saying many of its customers aren't ready to “rip and replace” their existing hardware gear to go to pure play open-source SDN solution. By adding OpenFlow, Application Programming Interfaces (APIs), and it own set of OpenDaylight-compatible applications, Extreme officials say they are ready to embrace the movement, which gives customers the best of both worlds by helping them preserve their existing investment in proprietary networking gear.

It's a good story, though Extreme trails many large networking vendors in adding SDN interoperability. When I visited Extreme early in the year, there wasn't a lot of excitement about SDN, and the company did not seem to have its story together. Dan Dulac, VP of Solutions Engineering with Extreme, says the recent merger with Enterasys has give Extreme more reason to focus on its SDN strategy. “There is a new focus there,” he says.

“We believe that mindshare that will be critical,” says Dulac. “We're looking to combine the ONF (Open Networking Foundation), OpenFlow architecture with valued-added proprietary APIs.”

Dulac says Extreme also sees it as a good chance to make inroads against unspoken market-share leaders -- perhaps Cisco Systems (CSCO) -- though Dulac did not name Cisco specifically, referring instead to market leaders. Cisco is widely recognized to own majority share in markets such as Ethernet switching and Wi-Fi networking gear.

“This is a disruption for the big guys,” says Dulac. “We believe we can bring the openness that is required to drive that mindshare. We have more to gain than to lose which is the opposite of the market leaders.”

Extreme says it will combine its own network management, analytics, and orchestration platforms -- NetSight and Purview -- with APIs that integrate with ODL and OpenFlow. It's unveiling its SDN strategy this week at its US Ignite event. It has also kicked off an “Innovation Challenge” for developers to create new SDN applications, with cash prizes to be awarded.

(Disclosure: Of the companies listed above, the author holds shares of HP (HPQ), for reasons having more to do with valuation than SDN.)