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 * Jake Snyder blog * CTS 039 – When and How To Use Spectrum Analysis * Mike Albano – Clients *