Hardware can play a major issue in poor WLAN performance. This can range from outdated system software on your APs to loose cabling on your antennas.
Out-of-date firmware is an often overlooked problem with radio performance.
Sometimes the firmware on your AP becomes out-of-date as new features are added. You can update the firmware if you load the firmware image from the manufacturer.
You can try to reset the AP's configuration. Disconnect power for a few minutes, and then reconnect. Alternately (as in the case of the Cisco 1100 APs), press the MODE button for 30 seconds. This resets the firmware image to its default settings.
You can also update your AP's firmware if you download the newest version from the Cisco website. Follow these steps to install it onto your AP:
Don't overlook the firmware on your client devices, too. You should make sure to upgrade AP firmware and adapter firmware. Also check release notes on firmware. This can tell you what the firmware updates, including any bug fixes.
Many performance and connectivity problems stem from configuration issues. If you have problems with WLAN performance and connectivity, check this place first.
You can spread out these settings through various screens in your AP's configuration screens or you can manage them via the command-line interface. Table 14-3 lists and explains the usual sources of configuration problems.
Radio signals are disrupted for several reasons. The most common include interference, which we discuss in preceding chapters. Interference comes from other RF sources (cordless telephones or neighboring WLANs, for instance) or from electromagnetic interference (from non-communications equipment, such as microwave ovens).
Other factors, however, can have an impact on your WLAN's performance. Although you might blame typical problems on radio interference, you might check the cabling, instead.
When you connect bridges or APs that are situated far from their antennas, it's best to keep the antenna cabling as short as possible, because signal strength degrades on long runs of cabling. Cisco provides a tool to help determine the maximum distance over which two bridges can communicate. The link to the Antennae Calculation Spreadsheet is contained in the "Other Resources" section in this chapter.
When cables connect your antennas to your wireless devices, problems can occur. Check your cabling, with a special eye for the following: