WLAN Triage with the Fluke AirCheck

Disclosure - I was provided an evaluation unit by Fluke Networks to review. However, all opinions expressed in this post are solely my own and in no way constitute a paid arrangement.

The Fluke Networks AirCheck Wi-Fi Tester has been around for a while now. And I'm late to the game, despite having seen its initial release as part of Wireless Field Day 1. I was impressed with the brief hands-on time that I had with the unit back in 2012 as part of that event, but I never had the opportunity to acquire one as part of my job.

I decided to revisit the AirCheck after observing some positive discussion of the unit on Twitter, watching Devin Akin's Fluke webinar, and realizing that its functionality appeared to align with my philosophy that airtime utilization is a key WLAN metric. I've only had a brief time hands-on with the AirCheck, but I'd like to highlight a few of my initial findings.

First and foremost, I view the AirCheck as primarily a tool for WLAN triage. When first stepping on-site to work with an existing WLAN that's experiencing problems, the AirCheck is a great tool to obtain an initial assessment of the environment. It turns on in just a few seconds, provides a snapshot overview of several key WLAN operational characteristics (more on these below), and the handheld form-factor is great because it's unobtrusive and allows me to gather data while walking through a facility while conversing with the network administrator or customer representative who is usually providing an overview of the environment. During this discussion, a quick glance at AirCheck data can trigger key questions that I should ask the customer and allows me to gather context surrounding the WLAN installation. In other words, the AirCheck helps me narrow down the source of potential problems quickly and efficiently.

Previously, I used the AirMagnet Wi-Fi Analyzer (formerly the Laptop Analyzer back in the day... yeah I've been around a while) for this triage functionality. However, that tool is getting a bit long in the tooth for my taste. And sometimes using a laptop isn't as convenient as an embedded handheld device. I should also note that the AirCheck comes as a software solution for use on Windows and Android devices as well, but I haven't explored it yet.

Some of the AirCheck features and metrics that I've found useful so far include:

Channel Usage
This screen gives a TON of useful information on multiple fronts:

  1. Channel Plan - what channels are being used, and are any non-standard / overlapping channels being used (e.g. channels 2-5 or 7-10)? Are DFS channels being used?
  2. AP Count - how many APs can be seen on any one channel? Are some channels overloaded while others appear unused? Is co-channel interference (CCI) a potential problem [hint - it usually is]?
  3. Channel Utilization - how congested are the channels? How busy is the WLAN? Could there be capacity constraints with the WLAN design that need to be addressed?

However, I have found that at times the AP count can be wrong. I observed this situation when the AirCheck can decode the vendor proprietary information element for AP name, the names for APs are longer than the allowed character limit and get cut off, and the AP names embedded are therefore identical. Essentially, the AirCheck will interpret multiple APs as a single AP in this situation, but ONLY in the Channel Usage screen; the AP List and SSID List screens display the multiple APs correctly and individually. Here is an example that I found in a hotel where two APs are only displayed as a single AP in the channel usage screens. Drilling into the details we can clearly see the different BSSIDs indicating two APs with two SSIDs each.

AP List
This screen provides a good overview of APs that can be heard from your current location. I use this to determine primary and secondary AP coverage quality, co-channel interference levels between APs, and assess how many SSIDs each AP is broadcasting.

For example, how many other APs interfere on the same channel as the strongest AP in my current location? Using this screen, I can get a good feel for AP separation and frequency reuse. The AirCheck makes checking coverage and CCI in problem areas quick and efficient. Also, if too many SSIDs are being used, causing excessive overhead, I'll flag that as a point to review with the customer for consolidation.

However, I do wish Fluke would display the signal strength as a dBm value in this screen rather than signal bars which are useless. They show dBm values in other screens and this needs to be consistent throughout all views.

Auto Test
The auto test functionality is nice because it runs a battery of tests and provides a summary of results. This is useful to save you the manual work of navigating between screens and manually identifying areas of concern that frequently arise. Rather than repeat that manual process at multiple locations throughout a facility, which can get tedious real quick, simply run the auto test. I should note that I recommend changing the default settings and thresholds on the AirCheck unit before running the auto test... more on this subject below.

So far the most useful information concerning the auto test feature that I've found is the air quality metrics, which include channel utilization by Wi-Fi and non-Wi-Fi sources and co-channel interference levels on each channel.

I've had a bit of trouble obtaining the companion AirCheck PC software that provides configuration of network profiles for connection testing and saving of session results. Apparently Fluke has a snafu on their website requiring a support contract to access the software. The Fluke team has been great in getting me access to the software, but due to the delay I have not had time to install or review the PC software functionality. Therefore, I can't provide an evaluation of the Network Test functionality, which might be useful to diagnose association or authentication issues. You can create network profiles on the AirCheck itself, but it is very manual. For example, you can't select an SSID from the list to configure authentication settings; instead you have manually type all of the information in. Perhaps Fluke can make this easier through a future update.

Customizing Thresholds and Auto Test Settings
One thing that I've found is the default thresholds and settings for auto test on the AirCheck unit require some adjustments to ensure the results and their interpretation are accurate. I'm very pleased with the configurability of these settings, but do wish Fluke would adjust the default settings to align with recommendations of WLAN professionals for most environments. A few of thresholds that I've had to modify are displayed below, they include: 802.11 channel utilization levels, air quality co-channel levels, packet retry rate levels, and the minimum signal threshold.

Overall, I'm very pleased with the AirCheck unit as a tool for initial WLAN triage. It helps me quickly assess an environment from my first steps within a facility without having to wait to boot a laptop and run more in-depth tools. This way I can get a quick overview of the WLAN that can equip me to ask relevant questions when being initially briefed by the network administrator or customer contact. It displays the information in an easily digestible format that is accessible to both the WLAN professional as well as field technicians that may not be as knowledgable about Wi-Fi. Apart from a few minor complaints, the AirCheck is a super tool. It won't replace more in-depth Wi-Fi tools that professionals rely on, but then it doesn't really need to in my estimation. I view it as a tool to assess and triage a WLAN network, allowing me to narrow the scope of potential problems quickly and focus on remediation.