It’s no longer necessary for enterprises to install dedicated Wi-Fi controllers in their data centers because that function can be distributed among access points or moved to the cloud, but it’s not for everybody.
While the arrangement is often referred to as controllerless, that is a misnomer; there is still a control plane, it’s just not located in a dedicated device.
The traditional data-center deployment of a controller really isn’t a strict necessity for enterprise WLAN use any more, according to Farpoint Group principal Craig Mathias,
“The controller is really a piece of functionality that is overhead today,” he said. “I’m not saying control is overhead … but having a separate piece of hardware to take care of that really is overhead. It’s an artifact of an earlier time."
The model for the earliest enterprise Wi-Fi implementations was “fat” access points, which contained their own control functionality. The downside of this was that, generally, each had to be manually configured, which won’t work for an installation of any real size. The controller’s ability to manage dozens or hundreds of APs from a single place has been critically important, but letting networking pros accomplish the same tasks without the need for a dedicated appliance is a major step forward.
Why controllerless Wi-Fi is a good idea
Distributed controller functionality uses the increasingly powerful hardware present in modern wireless APs to create a virtual controller, while cloud-based products simply handle the control plane on the service provider’s remote servers.
All major WLAN vendors have controllerless options these days, and they’re increasing in popularity, according to ZK Research principal Zeus Kerravala.
“Choices are what customers want – that’s why most of the large vendors have a variety of different options. I will say, though that there’s been a trend towards controllerless solutions – if you look at Cisco sales, they’re largely dominated by [cloud-based] Meraki,” he said.
Like anything else, it’s a case-by-case issue – neither architecture has an incontrovertible lead in performance or cost efficiency over the other, and some enterprises may find that traditional controller hardware is still the best choice for them.
“I still think we’re years away from the death of the controller,” said Kerravala.
Controllerless Wi-Fi shortcomings
The central drawback of a cloud-based Wi-Fi controller, for example, is vendor lock-in – without the cloud service, the access points will simply stop working, and it can be costly to upgrade and re-architect for either an on-premise controller or a different company’s controller-less service.
“If you’re gonna go down the cloud controller route, you’d better be sure that’s the path you want to take, because in general, once you go there, you’re not coming back,” Kerravala said.
Not all controller-less options are created equal – Cisco’s Meraki features a simple, intuitive interface but a limited feature set, while Aerohive provides much more control, albeit behind a more complicated UI.
“The companies that buy these have to understand how technical they are, what kind of control they want,” said Kerravala. “You’ve really got to do your due diligence.”