Posts

Cisco Gets a Case of Throughputitis

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Far be it from me to hate on a Wi-Fi vendor...

...but seeing Cisco's Wi-Fi recommendations for iPhones (and other Apple iOS devices) has led me to wonder whether The Cisco (Kid) is a Friend of Mine.
Cisco released a Best Practices doc for supporting iPhones, iPads, et al. back in November.  For whatever reason I missed it back then.  I'm bringing it up now because Keith Parsons had something about it on his Twitter feed and Ekahau has a webinar coming up on designing a Wi-Fi network for iOS devices.  
I am happy that Cisco is bringing up the topic of device-centric Wi-Fi design.  Wi-Fi is (or, at least, should be) all about the end user, and device-centric design implicitly acknowledges this.
I am less happy at several of Cisco's actual recommendations.  They seem to have fallen into the trap of believing (or, more perhaps more accurately, leading) the Latest Trendy Wi-Fi Disease, throughputitis.  
Throughputitis, as you all know, is Latin for "inflammation of the throu…

Assess Yourself

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Yo, man.  There's a lot of Wi-Fi installers out there flakin' and perpetratin', but scared to kick reality...
So what you want Wi-Fi engineers and admins to do?
Assess Yourself!  


To which you might respond, "Duh!"
Any networking or Wi-Fi person worth a lick knows that a network should be assessed before (and, in many cases, after) deployment.  What is far, far, far less well known is HOW to assess a Wi-Fi installation.  
Properly assessing a Wi-Fi installation involves two parts: assessing configuration settings and assessing the physical location of access points (APs) and antennas.  And if you don't assess both, you'll be making a sucker and you equal
While rolling through the streets of Searcy, AR in my main man GT Hill's 1984 Ferrari convertible, I was given some wise insight.  Not, "I only buy things that make money back," a former favorite quote of GT's prior to the purchase of said Ferrari.  Instead, it was wisdom about churches, whi…

Spectrum Deception

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When using Wi-Fi spectrum analyzers, it's good to remember an old Russian proverb: Trust, but verify.

Recently, I was doing some work for a company that needs BYOD Wi-Fi at several office spaces in multi-tenant buildings (insert: lame excuse for not blogging more) and we ran into what seemed to be an interference problem.
Why did I think it was an interference problem? I had already completed the following checklist:
1. Cisco AP transmit power set to level 2 or 3 (that's 20 dBm to 17 dBm if you're using 3600/3700/3800 APs)? Check.
2. RRM channels 2, 3, 4, 5, 7, 8, 9 and 10 disabled? Check.
3. Excess 2.4 GHz radios disabled based on a survey done using an iPhone 4s? (What can I say? I'm a big softy for users who over-extend the life of their smartphones. They're the real MVPs of climate change.) Check.
4. OmniPeek captures, done from potential "neighbor" trouble areas, to look for channels occupied by large amounts of Retry frames? (This one has become nec…

802.11ac Wave 2 and You, Sponsored by Extreme Networks

The latest and greatest Wi-Fi standard is here (sort of).  802.11ac Wave 2 is now available in real-world Wi-Fi devices (maybe) and it's ready to supercharge your Wi-Fi performance (under some circumstances).  
Since 802.11ac Wave 2 is brand new (based on a three year-old standard), a lot of folks are looking for clear information on it.  The technology is great (or, maybe over-hyped), but how can an organization tell whether it's time to upgrade?
Luckily, Sniff Wi-Fi (in a post sponsored by Extreme Networks) has just the solution for you: an eBook!  "The 5 Essential Elements in the 802.11ac Wave 2 Business Case" covers 802.11ac Wave 2 technology, compares it to previous Wi-Fi technologies and identifies specific ways that 802.11ac Wave 2 can improve Wi-Fi performance for a number of vertical markets (no, really, it does).
When it comes to Wi-Fi deployment upgrades, I find that organizations fall into one of three groups: 
1) Organizations that keep their Wi-Fi infrastru…

Giving Voice to the (Apps That Should Be) Voice-Less

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Wi-Fi Calling is here, and that fact is causing concern for some Wi-Fi folks.  Wireless LANs that were initially installed as a value-add may be tasked with carrying mobile, high-quality, always-on voice traffic.

The 802.11 standard has had quality of service (QoS) protocols designed to accommodate voice since 2005, when the 802.11e amendment was approved.  That's good.  What's bad is that some voice applications are over-prioritizing their voice traffic, and it could lead to capacity limitations.

First, some background on Wi-Fi QoS:

The original 802.11 standard deigned that all Wi-Fi traffic would be created equally.  That is a GREAT thing for most Wi-Fi networks.  If some namby-pamby user whines to an admin, "Hey, why are you placing that AP in the OTHER room?  I want the AP closer to me," the admin can tell him (or her; women occasionally complain, too) "look, buck-o (or, buck-ess), Wi-Fi gives equal throughput to everyone who's connected.  You'll conn…

Go To Sleep, Go To Sleep, Go To Sleep Little iPhone

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In some circles, Apple Wi-Fi devices are knows to have problems with lost connections.  iPhones and iPads will unexpectedly miss incoming calls, have delays in receiving push notifications and even be forced to reauthenticate.

There is a solution to Apple devices' connection problems, and as with most "device problems", the fix resides on the infrastructure.  The DTIM setting needs to be increased.  (Apple recommends a setting of 3 or higher.)  Here's why:

Some Apple Wi-Fi connection problems stem from Apple iOS devices' use of 802.11 power management.  To understand what Apple devices are doing with power management, one must first understand how 802.11 power management works.

Let's start with unicast data.  The 802.11 standard allows devices' Wi-Fi radios to enter the Doze state in order to conserve battery life.  Wi-Fi radios in the Doze state are unable to receive data from the AP, so APs buffer all unicast data that has a destination MAC address of a…