Spectral assurance in WLAN infrastructure is going to become a key requirement in enterprise wireless LANs. Cisco got there first, and my testing of their ClearAir technology shows that it works as advertised.
My review of Cisco’s CleanAir technology is up on Network World today, and, cutting to the chase, this is a terrific piece of technology that works as advertised. I have always been a huge fan of Cognio’s Spectrum Expert, which of course became Cisco’s Spectrum Expert with their acquisition of Cognio. Spectrum Expert was the first notebook-based spectrum analyzer, and I still use it – frequently – to this day. But, as I discussed earlier this year, the walking-around model (WAM) of spectral analysis and troubleshooting inherent in this approach, while still valuable, doesn’t scale. I remember asking, when being briefed on the Cognio acquisition over two years ago, for spectral analysis to be integrated into the WLAN infrastructure – what I now call the centralized/infrastructure model (CIM). Cisco is the first to ship such a solution, although a number of their competitors have announced and at least one (Aruba Networks) is shipping competitive solutions today.
OK, there is some debate as to where spectral assurance, as we call this functionality, should reside. Similar capability is also available in infrastructure-side sensors from a number of WLAN assurance vendors, like AirDefense and AirMagnet Enterprise. But keep in mind that detection must exist in the WLAN infrastructure in order to enable automated remediation. There’s also some question as to whether dedicated custom hardware functionality, the path taken by Cisco, or the use of the spectral-sensing capabilities emerging in some Wi-Fi chipsets today, like Atheros’ 9200 series, represent the “best” alternative. The key elements here, in addition to cost, of course, are temporal and frequency resolution, and the fact that a Wi-Fi chipset can’t be listening for interference (or anything else) while it’s transmitting. That’s why this space is so ripe for innovation, and with many forms of interference and related threats becoming more visible, I expect that spectral assurance, either in an assurance solution or increasingly integrated into the WLAN infrastructure itself, will become as common as, well, wireless LANs in the not to distant future. Yes, it’s that important, even as a number of implementation models will fight it out in the marketplace.
So I was really excited by the opportunity to get my hands on some Cisco hardware to try ClearAir out, and I was very pleased with the results. First, as noted above, it works. It’s easy to use, and well-supported in WCS. The detection of interference can result in the automatic re-assignment of Wi-Fi channels in APs, subject to the algorithm that Cisco uses here. Note that one might not want channels to change in the presence of insignificant or infrequent interference, and certainly would want to change channels so often that thrashing – with a consequential loss of capacity – occurs. ClearAir is very easy to configure and our tests show that it works.
In the meantime, as I noted above, spectral assurance belongs on your checklist of features required when thinking about that new WLAN that I know is on your to-do list. There’s no other way to verify the functionality of the wireless PHY, something that must be done 24/7 in any mission-critical environment – like, I’m sure, yours.
