Sniff Wi-Fi

  Show  of hands: Who here has seen Retry percentages above 90%? If you work with Wi-Fi, your arm is likely reaching skyward as if you're hiding Darrell Lea licorice from the kids. (Hope you wore deodorant today.) Juniper Mist is most notorious for it. Nyansa Voyance -- which is no longer a Wi-Fi thing -- used to do it too. Aruba Central even has a built-in alert for it. The problem is, 90% retries doesn't really exist (and of course, 100+% retries is impossible). When an AP repeatedly sends retransmitted frames (packets) to a Wi-Fi client -- and let's pause to point out that centralized WLAN management systems can only reliably know AP-to-client (not client-to-AP) retry statistics -- the AP will typically drop a packet before re-sending it so  many times that the wireless retry percentage would ever truly hit 90%. So why, then, do we see retry percentage near, at or above 90%? Because some (most?) Retry% calculations often use a denominator of successful  frames in...

"There are known knowns; things that we know we know. There are known unknowns; that is to say there are some things we do not know. But there are also unknown unknowns -- the ones we don't know we don't know. And if one looks throughout [history], it is the latter category that tends to be the [most problematic]." -Donald Rumsfeld, former United States Secretary of Defense For those of us who follow United States politics, the above quote is a famous one.  And for those of us who work in Wi-Fi, being aware of Unknown Unknowns can make the difference between good Wi-Fi and bad. What are the Known Knowns of Wi-Fi?  AP status (up or down).  AP channel.  Number of associated client devices.  Data statistics.  We can gather these pieces of information from WLAN controllers or wireless management systems. And what are Known Unknowns?  For one, we know that we don't know precisely which nearby APs and client devices are causing CCI.  We kn...

Apparently Wi-Fi at the White House sucks !  A journalist asked me what might help it, so I figure I'll share my response: Hi [Very Wise Journalist Who Reached Out To Me, Ben Miller, For Comment], In some ways the White House is like any other large, multi-user space and in other ways it is very different. Uncommon challenges at the White House are likely the result of security requirements and the need to maintain the historical integrity of the building.  The White House almost certainly has areas that are off-limits to AP installers and there may be limits on where cable drops can be made. There is a distinct line between good and bad solutions when AP locations are restricted.  The goal of both solutions is to increase coverage to hard-to-reach areas.  The bad solution, which is likely happening at the White House, is to increase the transmit power of APs.  Increasing AP transmit power aids downlink data sent from an AP to a Wi-Fi device, but ...