 Recheck connectivity with security settings temporarily disabled Replace the suspect access point with a known functioning substitute Users can connect to an Check that the client station and access point have valid access point but are IP addresses, sub-net masks and default gateway unable to access the addresses, either received from a DHCP server or network manually entered Use the ping command at the os prompt (e.g. DOS prompt) to check step-by-step connectivity, from client station to access point and from access point to a wired network computer If 802. 1x authentication is in place, verify configuration and operation of the authentication server over a wired connection Some WLAN analyser products focus on one application area, such as spectrum or protocol analysis, while others combine these specific capabilities with more general performance and security analysis tools. The typical usage of these analysis tools is summarised in Table 9-6. With the advent of 802.11i and the increasing use of 802.1x authentication in WLANs, successful authentication becomes an additional step before a client station can successfully connect to the network. A WLAN analyser will be able to monitor each step of the EAP Chapter Nine Table 9-5: WLAN Troubleshooting - Checklist for Performance Problems Root cause Description Poor SNR - low signal Use a site survey tool (Section "Troubleshooting using strength WLAN analysers, p. 243") to test signal strength at the affected location Monitor signal strength while adjusting antenna location and orientation Consider increasing antenna gain or transmit power (up to regulatory limits) or relocating access points if signal strength remains low Poor SNR - high noise Use a site survey tool to identify other 802.11 transmis- level sions and non-802. 11 interfering signals Look for and eliminate the usual suspects (microwaves, cordless phones, Bluetooth) if high noise levels are identified Access point overload Survey users for any changes in applications or usage patterns Turn on and revi