As networking becomes more and more about standard APIs, doesn't that mean equipment becomes more and more commoditized?

It's a fair question, and one that reflects what happens with certain standards. If all competitors are forced to make their products the same, each product's value drops.

I'm not talking about just white-box switching. The question also comes up regarding Layer 4-7 equipment, which sometimes sounds like it's getting reduced to an API call out of a software-defined networking (SDN) controller.

"Somebody coming from a programming background will say, 'Well, you're all using the same APIs. How is one different from another?'" says Steve Shah, senior director of product management at Citrix. "While you have a common set of APIs for a core set of behaviors, how you implement the APIs is where you're going to find that differentiation."

It's a point Citrix wants to drive home, because the company is getting so closely intertwined with Cisco and its Application-Centric Infrastructure (ACI). Software called a device package gets added onto Layer 4-7 gear so that it can work with ACI. To someone not familiar with Netscaler, it can look a little bit like ACI is now controlling a generic application delivery controller (ADC).

But even under a heavy SDN regime, ADCs will differ, Shah contends. For example, in instantiating a load balancing policy, Citrix could add various other functions, such as security or WAN optimization. "Someone who wants to bring up a Netscaler in that environment has 13 different functions they can get out of that one instance, whereas if you followed the API to the letter and didn't deviate from that first turn-on policy, you might only have three or four different functions you're going to get out of that API," Shah says.

Another way to think about this is in terms of openness, writes 451 Research analyst Peter Christy in an email to SDxCentral. APIs provide the openness that customers like, but it's rare to find an API that provides perfect interchangeability between vendors' products — and it's that interchangeability that would truly make the gear genearic.

"It’s possible to define interfaces so rigorously that you can really test something before it ever connects through the interface, but that’s not the usual case. Usually it takes a partner relationship (more detailed explanation and support) to make things work," Christy writes. Sometimes, certification testing is necessary, too — because it's possible to support the API while still having the devices on both ends work poorly together.

Shah likens it to Ethernet packets. They have headers that follow a standard. But vendors differ in how they process these packets and what rules they apply to them. Not every Ethernet switch is the same, and high-end switches — defined in terms of features, not just port speed — do exist.

All of this is important to Citrix because the company has no ambition to replace orchestration (and no ammunition for it, really). Citrix's goal is to remain a Layer 4-7 player and fit itself into other software-defined network schemes. APIs are a likely way to do that.

F5 is taking a different approach, offering its BIG-IQ platform for management and orchestration, part of a broad architecture named Synthesis.