data rates

CTS 108: Useful Wi-Fi Metrics To Track

Which Wi-Fi metrics are worth tracking and what can you do with those metrics?

This episode was sponsored by Metageek

Sponsored by Metageek

Useful Wi-Fi Metrics To Track

Today’s Wi-Fi networks are the main point of access to network resources and have become mission critical service to employees. To monitor the Wi-Fi network, which metrics should you track to show the Wi-Fi network is performing optimally? We list our six useful Wi-Fi metrics worth tracking.

RSSI

  • Most looked at metric
  • Determines the strength of the signal
  • Good to get both from AP and client perspective. Client may hear AP loudly but not the other way around

SNR

  • Indication of signal quality
  • Difference between the signal and noise
  • Example: concert, kids talking over parents

Channel Utilization

  • How busy the channel is
  • Both 802.11 and non-802.11 traffic
  • Congestion and capacity
  • If youre seeing high channel utilization you may need to add more capacity
  • Tells us if CCI is an issue

Data rate

  • Especially useful on the client side
  • Tells us how well the client is able to decode the Rx signal
  • Tells us how the driver is handling data rates

Retry Rate

  • Does it correlate with high channel utilization
  • Are basic data rates too high
  • If you’re seeing too high (10-15%) retry rate look into lowering data rates, look at potential interference, maybe even hidden nodes or devices with bad drivers

Association Time

  • Why would it take a long time to associate
  • Bandsteering could cause long association times because of delayed probe responses
  • Are devices scanning DFS channels
  • Can client and AP hear each other

CTS 054: 4 Scary Things Lurking in Your Wi-Fi

In the spirit of Halloween I wanted to go into a theme of scare and fright. While these may not make the hair on your neck stand, I don’t know maybe they do, these issues can lead to managing a scary wireless network. Scary because of end user complaints and because these can be running on newer wireless networks.

Those four scary things are

  1. Low data rate clients
  2. WPA2, even WEP
  3. 2.4 GHz Zombies
  4. Non Wi-Fi Interference

But before we jump into those 4 things, I wanted to update everyone on my journey to CWNE. This weekend I decided to take the CWDP exam. After a little under a month of studying I successfully passed.

The biggest resource I used was the official study guide by Tom Carpenter. It covered all the objectives of the exam. I felt this one was easier for me than the CWNA or CWAP. The topics were straight forward and common sense. This is probably because of my experience coming from designing some wireless networks but it came natural for me.

Now I plan on tackling the CWSP. Probably my weakest area but I look forward to learning from the Sybex book that was released in September 2016. I also plan on doing quite a few labs to get the security topics down.

4 Scary Things Lurking In Your Wi-Fi

Low data rate clients

Low data rate clients take longer to communicate over the air. They slow down devices trying to communicate on faster data rates. This makes it an inefficient wireless network.

An easy solution is to disable lower data rates such as 1, 2, 5.5, 6, and even 9 Mbps.

Keep in mind that this will shrink your cell size. So design properly!

WPA2, even WEP

I’ve seen some networks still utilizing WEP. There’s no use for this anymore. It’s been proven to be insecure and newer devices support much stronger encryption. WPA2 is also now crackable so it’s time to use stronger security.

Both security methods are a management nightmare because a passphrase has to be changed on every device.

The best solution here is to use RADIUS as much as possible. Keep WPA2 only devices on a separate SSID.

2.4 GHz zombies

The IoT band. The land of interference. A place where all single band clients get together. 2.4 GHz is a crowded spectrum.

Move your clients to 5 GHz as much as possible to avoid the congestion seen on 2.4 GHz. To troubleshoot issues on 2.4 spectrum use a protocol and spectrum analyzer.

Non Wi-Fi Interference

This also relates to the previous item. Non Wi-Fi interference causes high retransmissions on the network. This leads to low throughput.

End users characterize this as slow Wi-Fi, unusable, and poor performance.

Start looking into causes of anything over 15% retry rate. You can use tools such as Wireshark or Metageek’s Eye P.A.

Check out this previous episode around Spectrum Analysis while you’re at it.