Sniff Wi-Fi

Last week's blog about Wasted Wi-Fi prompted some questions about AP transmit power in the enterprise.   Let's answer some of those questions by doing a little Q(-Tip)&(802.11)A, an exercise in which we watch a Q-Tip video before Answering a few questions about Wi-Fi. You've seen the Q(-Tip), now on to the A(nswer)s: Wasted Wi-Fi is all about APs and/or stations making inefficient use of a Wi-Fi channel.  When Wasted Wi-Fi happens, either data rates are lower than they should be, or Retry percentages are higher than they should be. The Q becomes, where do equivalent isotropically radiated power (EIRP), transmit power and conducted power fit in? The A is, higher data rates and lower Retry percentages tend to happen when signal-to-noise ratio (SNR) is higher, and higher EIRP/conducted power/transmit power leads to higher SNR. In other words, if you talk louder, then people hear louder.  When people hear louder, they have a better chance of being able t

Remember me? (lyrics NSFW) Too many enterprise Wi-Fi deployments experience Wasted Wi-Fi.   Wasted Wi-Fi is what happens when an enterprise wireless network offers users lower performance than it would under an optimal configuration. Today, the most common culprit of Wasted Wi-Fi is low AP transmit power.  So, if your AP transmit power config is Still Down, Raise 'Em Up. I've noticed a lot of Wasted Wi-Fi recently.  Situations where, given the distance, client density, and physical environment, the Wi-Fi should be faster.  These are situations where, irrespective of issues that may exist in the infrastructure equipment or design of the wireless LAN, client devices are getting worse performance than they should. By its definition, Wasted Wi-Fi lays entirely at the feet of those who configure enterprise Wi-Fi settings.  The good news is, that means Wasted Wi-Fi is solvable without expensive and time-consuming changes to the wireless LAN infrastructure. 

Editor's note: In the original publication of this article, the relationship between Wi-Fi channel width and SNR was described imprecisely.  While the point of the article was correct -- that wider channel widths increase the likelihood of Wi-Fi frame failures for mobile client devices -- the mistakes have been corrected.  Thank you to Adrian Granados . Ahh, roaming. Few things capture the spirit of freedom like the ability to Roam wherever you want to go. Wi-Fi has its own brand of roaming, and there is one aspect of Wi-Fi roaming that often gets overlooked: 40 MHz and 80 MHz wide channels can make Wi-Fi users feel like they've been bounced from the Love Shack. Much has been written and spoken about the pros and cons of the three Wi-Fi channel widths: 20 MHz, 40 MHz, and 80 MHz. 20 MHz wide channels allow for the highest number of APs to be deployed -- nice for ultra high-density Wi-Fi -- because each AP takes up less of Wi-Fi's scarce frequency space.  In

After eight and a half years, one hundred forty posts, and a shade under one-and-a-half million page views, it is clear to me that one topic causes more controversy than any other on this here Sniff Wi-Fi blog: disabling low OFDM rates (such as 6 & 9 Mbps). Wi-Fi vendors tell you to do it. CWNP trainers tell you to do it. Other bloggers tell you to do it. I (and a very, very small group of other hardcore Wi-Fi professionals) tell you   not to   do it . But this blog post isn't about re-litigating that controversial issue (for the most part).   This blog post is about telling you why I **did** disable the 6 & 9 Mbps data rates on a recent Wi-Fi optimization project. Given the subject matter of this blog post, I feel compelled to begin with some shameless self-promotion: if you have a problematic Wi-Fi deployment (or if you're in the "design" phase and you want to avoid having a problematic Wi-Fi deployment, or if you would like training on how to a

If I sound a little bit surly today, it's because I spent last night watching this: For those who don't follow basketball, that's the brilliant Nikola Jokic (likely named in honor of wireless pioneer Nikola Tesla !) dissecting my beloved Milwaukee Bucks . If the result of the game -- the Bucks losing by 11 points in Milwaukee -- didn't make me surly on its own, my Wi-Fi experience yesterday surely didn't help.  The Wi-Fi in the Southwest Airlines terminal at LAX was slow and unstable, and the Wi-Fi at the aforementioned game (held at the 18,717 capacity Bradley Center) was mostly unusable in the seating bowl.  But what good does it do to stay surly?  Instead, I'll offer some tips on getting Wi-Fi working at high occupancy spaces. High occupancy Wi-Fi is a sensitive issue for me for two reasons: 1) I'm sick of fixing high occupancy deployments, and 2) As a frequenter of high occupancy areas, I'm sick of bad Wi-Fi in those areas. The trouble i

The vast majority of Cisco Wi-Fi networks can be fixed without having to spend precious time and money on surveying, adding new access points (APs) or moving existing APs.  Here's how. Cisco has some very fine enterprise Wi-Fi products.  Unfortunately, those very fine products often get deployed in a manner that leads to connectivity and performance issues. The following steps take about ten minutes to perform, and will stabilize connectivity and performance for the vast majority of enterprise-class Cisco Wi-Fi networks.  Anything in bold  is something to click or select or check or uncheck or type. 1. Access the Cisco wireless LAN controller (WLC) interface via a web browser. 2. Navigate to WLANs  (menu) -> -> Security  (tab) -> Uncheck WPA Policy  -> Apply NOTE: Wi-Fi Protected Access (WPA) is a Wi-Fi security method that uses temporal key integrity protocol (TKIP) encryption by default.  Using TKIP encryption disables 802.11n and 802.11ac data rates, effe