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

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