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Wireless networking has been a transformative force in network access for 20 years. From back in the slow days of 802.11 and .11b wireless standards to today, with many enterprises using fast 802.11ac Wi-Fi networks as the dominant network access method, the need to troubleshoot the wireless LAN has not gone away.
Unlike Ethernet running over a tightly controlled physical infrastructure, wireless networks have a slew of variables that contribute to their performance and perceived quality. When troubleshooting Wi-Fi network issues in business settings, these six steps will help you untangle the mess.
1. Understand the scope of the issue. When trouble tickets come in, it's time to troubleshoot. Whatever the problem, it's important to note how many clients or devices are struggling and whether you can easily replicate the problem yourself. In healthy, well-designed wireless LAN (WLAN) environments, most network issues are single-user problems. Check for driver updates, client configuration settings or account issues. Don't create more problems by making big network changes for small, local problems.
2. Remember: Many wireless network issues are not actually wireless. Everything feels like a wireless issue to Wi-Fi users when problems hit. Gathering good information on the specifics of the problem will help you realize what you're facing. When "the Wi-Fi sucks," it's likely you have problems with the following: Dynamic Host Configuration Protocol, domain name system, Network Address Translation, a saturated internet service provider connection, authentication server issues or routing troubles. Well-designed WLAN environments seldom suddenly melt down. But WLAN is not an island. It is integrated with many other parts of the bigger network environment. Understand your overall topology and know how to read core network problems that manifest themselves through Wi-Fi client issues.
3. Speed tests only go so far. You can't really troubleshoot network issues with an iPhone and an internet speed test utility. To troubleshoot, you need to know what access point you are connecting to and which radio on that AP. Other important questions include the following: How many other clients are on the AP? And how high is the AP's utilization? Is the uplinked switch port showing the right speed, duplex and Power-over-Ethernet value? A speed test is a spot check; it is not troubleshooting.
4. When Wi-Fi trouble hits, remember the basics of radio frequency (RF). You've ruled out individual clients as the source of an issue, and your core services are fine, leaving you with a localized Wi-Fi problem to solve. Get client media access control addresses and trouble time stamps -- both are a must -- and research signal strength and quality over the trouble period. If troubleshooting live, do it from where the trouble is happening, and check your own signal strength and quality. Low strength may mean a radio died or is running with insufficient output. Poor quality, as measured by signal-to-noise ratio or high channel utilization, can be a sign of RF-side problems between APs or outside interference sources.
5. Be prepared to capture packets. Occasionally, in the wireless world, you get a zinger of a network issue. When all the obvious troubleshooting steps have been taken, capturing packets and knowing how to read what you've gathered can be pivotal to finding a resolution. I've found clients with defective power-save mechanisms and APs not performing as configured through packet capture. It's an advanced skill, but it gets even trickier when done in the WLAN space. But, if you get comfortable with it, you will find problems that can't be flushed out any other way.
6. Don't trust vendor code. For what modern WLAN systems cost, you'd expect top-notch code to underpin important building blocks, like controller and AP operating system code. Unfortunately, many network issues come directly from defects in system code. Wireless networks are getting more feature-rich, which also means more chances for defects in the logic behind those features. Be sensitive to code updates and whether new user-facing problems might coincide with those updates. Sadly, even market-leading vendors often get it wrong. Don't be afraid to open a support case. But be prepared to provide a lot of logs and debug information and to argue your case, if needed.
The best way to prevent most wireless network issues is through proper system design and configuration. When you start to troubleshoot, it can be hard to know how to proceed, especially if you don't do it often. The six steps outlined here are a solid foundation to get you started and keep you grounded when wireless network issues do hit.