While the software defined networking (SDN) movement is still alive and trying to evolve the concept. There also the notion of Open Networking is especially being pushed by the Open Compute project. What this means in a nutshell or basic terms is that a customer can buy a bare metal switch with no native operating system (NOS) and then get the Operating system from another vendor. Of course this in itself is not SDN although many of these software companies does have some concept of SDN. Lets look at a few of these companies especially on the software side:
1. Big Switch - Their current solution is built around Openflow but they supply both the switch OS and the controller in order to build out a solution. They do allow you the choice of hardware from certified vendors. Switchlight is built on the Open Networking Linux (ONL) which is part of OCP.
2. Cumulus - This solution is built around the Linux OS which allows you the flexibility to develop applications that is tailored to your network needs.
3. Pluribus - The concept of a network fabric does allow ease of management and therefore allows more predictability for application deployment especially using the fabric API concept.
4. Pica8 - Openflow focused switch OS but does have a very mature traditional protocol suite.
Those are the main players today in the open networking arena as independent switch OS providers. The question that comes to mind is; How well does these different offerings play together? This is where standards could play a better role over time. The customer has choice in hardware but today it would be difficult to pick multiple switch OSes and get a clean infrastructure management story.
One good narrative is to standardize on a protocol like Openflow then settle on say Open Day light (ODL) as the main foundation for a controller (Vendors can deliver controllers leveraging the ODL base). Once that is in place, then vendors would focus on delivering applications as their main differentiators. This will probably not happen any time soon but there maybe a case to build out open standards to really enable choices.