The company announced the Flex 7500 Series Cloud Controller at Interop last week, which centralizes control and management functions in the “private cloud” data center but allows for distributed data forwarding in local branch APs.

Connections and inter-AP fast-roaming capabilities stay up if there’s a WAN failure between the branch site and the controller, and users can also authenticate locally, according to Greg Beach, director of product management in Cisco’s wireless networking business unit.

The Flex 7500 is a “1 [rack-unit] appliance that supports 2,000 APs [across distributed sites], local authentication and fast roaming. If a WAN link goes down, already connected devices survive,” he said.

The architecture alleviates the high cost associated with having a controller in every site in enterprises that are highly distributed, such as retail organizations.

However, the control and management functions are inaccessible if the WAN is unavailable. Cisco wireless VP and general manager Ray Smets said at the show that “retailers want CleanAir,” Cisco’s well-received spectrum analysis capabilities for identifying and mitigating sources of interference. “To get CleanAir, they need a controller. And they want that controller in the data center.”

In other words, while a WAN failure would not impact local connectivity and data forwarding, continued operation of the bells-and-whistles RF management features such as CleanAir remain dependent on a live WAN.

That’s because while CleanAir uses purpose-built ASICs in Cisco APs for monitoring, you need a correlation and analysis engine to crunch the data collected. According to Cisco CleanAir documents: “You can deploy Cisco CleanAir technology effectively with just Cisco Aironet 3500 Access Points and the Cisco WLC for simple detection and mitigation of RF interference. For added benefits such as location, zone of impact, policy enforcement, and visualization of air quality, you should also consider including the Cisco Mobility Services Engine (MSE) and the Cisco WCS [Wireless Control System].”