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...

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 ...

Do you own, manage, or provide technology services for a classy hotel?   Yes??   Then this blog's for you.   No, we are not going to reveal the secrets of luring wealthy clientele via watered-down booze and disreputable ladies.  Those things are obvious, and if they're not obvious you should ask a French person.  (One of my best friends is French, so I can say that...  I think.)   We are going to reveal how to quickly validate your other most important service -- Wi-Fi -- using free, built-in Mac software. The nice thing about providing Wi-Fi service at an upscale hotel (or other hospitality environment; convention centers, cruise ships, et al. count too) is that wealthy people hate to complain.  (Publicly, that is.  Privately that's all they do.)  The not-so-nice thing is that wealthy people are big fans of ghosting.  They will abandon your upscale hotel with the quickness if service of any kind dips ...

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.  ...

"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...

It's summer in Los Angeles, which can only mean one thing: Sequels! As movie fans indulge in a third 'Avengers', a fifth 'Jurassic Park', and what feels like a seven hundreth 'Star Wars', this here blog is providing a sequel to a probably-long-forgotten Sniff Wi-Fi post called ' Why Are You Slowing Down My Wi-Fi, Apple? ' Turn down the lights, pop some popcorn, and enjoy the twists and turns of this harrowing look into Wi-Fi Calling on iPhones. Several months ago, this blog highlighted the Wi-Fi behavior of the iPhone X  using OmniPeek.  Truth be told, that post was a little bit like the latest 'Spider-Man' sequel: attention-grabbing title, some interesting content, but ultimately nothing consequential.  And just as movie fans knew that Michael Keaton's flying bird character wasn't going to beat the lead superhero,  a lot of Wi-Fi folks already knew that Apple iOS devices use Protection (called a "TXOP" in the blog po...

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 ...