Note: High error counters on radio interfaces on the client, the access point or bridge indicate the effects of RF interference. You can thus determine if you want to change frequencies. The test shows any activity on your frequency and the other frequencies on which the equipment can operate. If you suspect radio interference with transmission and reception on your WLAN, turn off the equipment that operates on the frequency in question and run the test. This test generates a rough display of activity on the different frequencies. The Carrier Busy test available in the Test menus of Cisco Aironet bridges functions as a substitute for this item. As a result, other transmitters can broadcast on the same frequency that your WLAN uses.Ī spectrum analyzer is the best tool to determine the presence of any activity on your frequency.
You do not require a license to operate radio equipment in the 2.4 GHz band where the Cisco Aironet WLAN equipment operates.
The most common issues are radio interference, electromagnetic interference, cable problems, and antenna problems. Many factors impair the successful transmission or reception of a radio signal. The distance of the longest radio link in the set of bridges is entered in kilometers, not in miles. Enter the parameter only on the root bridge, which tells the repeaters. The Distance parameter adjusts the various timers used in radio protocol to account for the delay. Therefore, the time that the radio signal takes to travel between the radios can become significant. The radio link between bridges are sometimes very long. But, if there is some impairment in the communication that requires the units to fall back to a lower data rate, the unit set for 11 Mbps fails to fall back, and communications fail.Ĭisco recommends that WLAN devices are set to communicate at more than one data rate. If one of a pair of bridges has a data rate of 11 Mbps set, and the other is set to use any rate, then the units communicate at 11 Mbps. If the pair of devices are configured to use the same data rate, other factors probably prevent them from reaching that rate. If one bridge is set at a data rate of 11 Mbps and the other is set at a data rate of 1 Mbps, communications fail. Here are some common scenarios:īridges are used to communicate between two buildings. If WLAN devices are configured for different data rates (expressed in megabits per second), the devices fail to communicate. Lower data rates (such as 1 Mbps) can extend the coverage area farther from the AP than higher data rates. Data Rateĭata rates affect AP coverage areas. If you have not configured the frequency as Automatic, ensure that all the devices in the WLAN infrastructure are configured with the same frequency. The device scans the frequency spectrum, either to listen for an unused frequency or to listen for transmitted frames that have the same SSID as the device. Radio devices are set to automatically find the correct frequency. Units with different SSIDs fail to communicate directly with each other. Service Set IdentifierĬisco Aironet WLAN devices must be set to the same Service Set Identifier (SSID) as all the other Cisco Aironet devices on the wireless infrastructure. These parameters include the Service Set Identifier, frequency, data rate, and distance. If you configure the parameters incorrectly, the problem that results appears to be a problem with the radio. You must configure certain parameters properly for the devices to communicate successfully. When you encounter radio communication problems, the configuration of the WLAN devices can be the cause of the radio failure.
Wireless LAN Controller (WLC) Software Upgrade
Upgrading IOS on the 1400 series Wireless Bridge Upgrade Cisco IOS on an Autonomous Access Point Upgrading VxWorks Firmware from the Console You can find the directions to upgrade firmware at:
Use the Cisco Downloads ( registered customers only) to obtain updated drivers and firmware.
Use the most recent version of the driver or firmware with your WLAN products. If you encounter a radio communication problem with your WLAN, ensure that each component runs the latest revision of its firmware or driver. Occasionally, you can trace a problem with the radio signal to a problem in the firmware on the communicating devices. Refer to the Cisco Technical Tips Conventions for more information on document conventions. This document is not restricted to specific software and hardware versions. There are no specific requirements for this document. RF impairments that include antenna and cable problems You can trace problems with the radio frequency (RF) communications between Cisco Aironet WLAN components to four root causes: This document addresses some of the major issues you encounter when you try to establish a radio link between elements of a wireless LAN (WLAN).