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CTS 052: How To Validate Wi-Fi Infrastructure

In this episode, I talk with Francois Verges of Semfio Networks about how to validate the Wi-Fi infrastructure.

Validating a Wi-Fi network involves many steps. This is not isolated to a new deployment but also to an existing Wi-Fi network. Francois and I talk about what to validate, look out for, and what resources are available to assist on the job.

Validate Physical Installation

  • Walk through the facility
  • Validate
    • AP installation
    • Antenna orientation
    • With the customer
    • Telco room location

Post Deployment Survey

  • Use your survey laptop and try to use a business critical business device as well (VoIP phone, handheld scanner…)
  • Connect to the infrastructure. Use the most business critical SSID.
  • Use Ping or iPerf to test connection, roaming, throughput.
  • Things to look at while performing the exit survey:
    • What band is the survey laptop using?
    • What band is the client device using?
    • Am I roaming as expected
    • RSSI of both your laptop survey and the client device
    • If you use ESS, you can also connect 1 or 2 dBx antenna to perform a parallel spectrum analysis. (Detect noise and major interferences)

Things to look at after the survey:

  • Coverage
  • Channel distribution / Channel re-use
    • See if some Tx Power need to be adjusted
    • See if some radios need to be disabled (2.4GHz)
    • See if more 5GHz channels are needed
    • Making sure that all the configured channels are being used.

Spectrum Analysis

  • Study both bands: 2.4GHz is usually where you will find the most external interferences
  • Stay still at one location. If you see something unusual, move around to pin point the exact location of the source. (might not be easy). – Plan for a little extra time.

Packet Capture

  • Get a better idea of the RF environment (using Eye P.A.). Thing to look at:
    • Retry rates
    • Channel airtime utilization
    • Data rates
    • How the neighbours can be affecting some channels
  • Being able to see more advanced radio configurations such as:
    • data rates
    • AP capabilities
    • Client capabilities (Big one)
    • Being to spot unusual behaviours
    • Being able to troubleshoot some client issues

Analyze Client Behavior and Configuration

  • Make sure all the client devices of the same model have the same Wi-Fi NIC drivers
  • Make sure all the client devices of the same model have the same Wi-Fi configurations
  • Make sure they manage to connect to the Wi-Fi network (Check delays, does it take a long time to connect?)

Perform Functional Validation Testing

  • Grab a client device, roam around the facility (especially where the device will be used)
  • Validate how the client roams
  • Validate on what band the client connect to
  • Try to ping the application server and see if you lose any pings (make sure it does not affect production)
  • Validate voice quality if it’s VoIP
  • Validate throughput if the requirements need it (try to use the same applications as the one what will be used on the Wi-Fi)

Links and Resources