At a conference I attended in late 2013 or early 2014 (I’ve forgetten which one), I was privileged to hear Sarwar Raza (HP, ONF) discuss the challenge of creating and implementing SDN northbound interfaces (NBI). Then at the Open Daylight Summit in February 2014, I found myself in a conversation with Colin Dixon (Brocade, formerly IBM, ODL) where we discussed NBI a bit more.
What’s a northbound interface? Well, if you think of an SDN controller in the middle, network devices like switches on the bottom, and applications on top, then “northbound” interfaces are what applications use to communicate their network needs to the SDN controller. That’s the simplistic view, anyway.
The challenge with NBI right now is standardization. There’s many controllers on the market already, and more to come. Plus, there are many sorts of applications out there, as well as many different categories of “things” that an application might require of the network to meet its needs.
So, with a diversity of controllers and plethora of needs, is it time to standardize NBI? If so, how does the industry tackle this problem? The payoff is potentially huge: SDN application portability across SDN controllers from different vendors managing different sorts of networks. But, standardizing NBI is far from a no-brainer. NBI is a challenging project to take on. How should NBI APIs be classified? What sort of functionality should be codified? What’s do be done about existing vendor SDN ecosystems, if anything?