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

• Jake Snyder blog
• CTS 039 – When and How To Use Spectrum Analysis
• Mike Albano – Clients
• Ekahau Site Survey
• Metageek Chanalyzer and Eye P.A.
• Airmagnet