Automated 802.11 Spectrum Analysis/Remediation: Benefits And Implications

With recent press releases by Cisco and Aruba Networks regarding their emergent distributed spectrum analysis capabilities, many of us in the WLAN big leagues are sitting up and taking note. Sure, we've had tools like all of the Cognio-esque spectrum analyzer variants to schlep around when need be, and today's better wireless systems try their hardest to express their discomfort graphically when interference is afoot, but what is about to be unleashed is nothing short of huge. Huge on the order of an ultra-sophisticated Air Force electronic reconnaissance plane off of some potentially unfriendly coast, soaking up signals, doing automated cataloging, and feeding them to a highly skilled analyst who decides what to do about them.

Cisco calls it Clean Air. Aruba calls it Spectrum Analysis. And no doubt, the rest of the market will follow with their own versions. What is so exciting about this latest wave of wireless utilities? Basically, they act as force-multipliers. By equipping each access point installed with high-end WLAN spectrum analysis, classification and recording capabilities, You-The-Admin have now become You-The-All-Seeing-Admin. From your management console, you will have better intelligence than is typically gathered by sending even a sharp technician afield when RF issues are suspected to be affecting performance issues.

Simply put, everywhere you have an AP, you have a spectrum analyzer that can be leveraged from the central management system. In my world, that means I have potentially 2,500 or so spectrum analyzers working for me, if I use either Cisco or Aruba's product sets. Cisco takes it up a notch a separate chipset onboard their APs, specifically for dedicated RF analysis and the ability to differentiate things like the model of cordless phone causing the trouble. This is why their 3500-series 802.11n APs recently won Best of Interop for Wireless & Mobility. The 3500s can also serve clients as they simultaneously do analysis. Slick.

Can you have too much of a good thing? It's a fair question as this sort of intelligence gathering is bought and distributed. Given that 802.11n is predicted to be an Ethernet-killer, having healthy, noise-free air gets all the more important, especially where high-bandwidth and critical applications are moved to the radio side of life. At first blush, the thought of high-end, reliable, on-demand cell quality quantification is almost intoxicating in its appeal. But after the initial warm-fuzzy fades, it's OK to ponder if this new capability brings any baggage.

Let's use Syracuse University as an example. With a campus bordered by three hospitals, residential neighborhoods and a number of businesses, we see a lot of "edge interference" that we can only catalog and then ignore; it is all unlicensed spectrum, after all. Even though we do a pretty impressive job of reigning in rogue (self-installed) wireless access points and routers, we still have a running meteor shower of transient noise and interference sources within our borders. We know of dozens of RF-based classroom response systems, Zigby-style building sensor networks and research projects using the same 2.4 and 5 GHz spectrums used by our access points and clients.Add to this thousands of microwave ovens, Bluetooth keyboards, mice and headsets, as well as a bazillion low-end wireless printers in our dorms that came out of the box with radios enabled but only get used via USB cable, and you start to get the picture. Let's not leave out dozens and dozens of Wi-Fi-equipped vehicles moving around campus, from delivery trucks to buses and limos. When I think about the sheer volume of signals zipping around within my area of responsibility, the word "overwhelmed" is never far from front and center.

The diagnostic advantages of Clean Air and it's competitors are obvious, especially when the system lets you essentially reach back in time to see what may have been going on RF-wise yesterday in a given area when trouble tickets are slow to work their way through the system. But with screen after screen of potentially actionable intelligence, we'll have to draw our own lines on what we react to. If a given space seems heavy with offending devices, but no one's complaining, do we still go out and proactively clean house by lecturing those in the area that they've got the conference room Bluetooth keyboard too close to our access point, and oh, by the way, can everybody not use the microwave oven in the break room until we can get someone to fund one that's more RF-quiet?

Or do simply marvel at thousands of more data points in the form of functional eye-candy without really doing anything about what we see until someone grouses? Remember, 11n will give us "9 times this and 5 times that" and re-grow hair on your bald spot if you buy all of the vendor hype, but not if radio conditions are compromised by all of the many devices that we have in use in the normal course of business.

Thankfully, the smart wireless systems in use today are adept at managing their own power and channel to hopefully dance around the varying conditions that the new distributed-spectrum analysis tools are meant to track. But it's still radio, and that means weird things can happen. Given that Murphy's Law says that most weird things will happen either at the worst possible time or when no one is around to react, the power of products like Clean Air will make a difference in keeping the reliability where it should be in high-reliability 11n networks. But first, we'll have to do two things: establish a whopping collection of known signals that we simply can't do a thing about from a practical standpoint, and then we have to develop a mindset and policy that guides how and when we remove competing devices. Once we get there, yes, these tools will be sweet.