3: WLAN Troubleshooting - Solution Strategies Solution approach Description Test one hypothesis at a time Whether it is a configuration setting or a physical layout that is being tested, make changes one at a time SO that effects can be directly attributed to a single cause. Test hardware using a known The easiest way to identify a hardware fault is to functioning substitute replace the suspected item with a known functioning substitute - whether it is a length of CAT 5 cable, a NIC or an access point. Keep a record Make a note of the changes that are made, any initial settings that are altered and the resulting response of the system. This will ensure that time will not be wasted in reinvestigating old avenues and that the previous set-up can be reinstated if changes make things worse. Check for unexpected side Before declaring a problem solved, check as far effects as possible that new unwanted symptoms have not been introduced as a consequence of the solution of the original problem. When everything else fails Read or re-read the hardware vendor's installation read the instructions instructions and check their Web site for specific information on problem diagnosis and troubleshooting. Figure 9-1: WLAN Network Analysis Tools (Courtesy of Fluke Networks) Wireless LAN Troubleshooting Table 9-4: WLAN Troubleshooting - Checklist for Connectivity Problems Problem symptoms Checkpoints A single user is unable Check that the wireless NIC is not disabled and that the to connect to any access station has adequate received signal strength point Check whether another client station is able to connect at the problem location Check the configuration of the client station's wireless network connection, including security settings Check that access point security mechanisms such as MAC filtering are correctly configured for the client station Replace any suspect wireless NIC with a known functioning substitute No user is able to connect Check the configuration of the access point, including to an access point security settings