Core Issue
There are several factors that can affect communication in a WLAN network. They are:
- Radio Frequency (RF) interference
- Configuration issues
- Firmware and hardware problems
- Improper antenna alignment
Resolution
To resolve this issue, perform these checks:
- Ensure there is no RF interference that may affect the WLAN communication.
The sources of RF interference must be identified and eliminated. Alternatively, try to use a different channel which does not have RF interference. Spectrum analyzers are devices that identify and measure the strength of interfering RF signals. The Carrier Busy Test utility on the Cisco Access Point (AP) and bridges can also be used to check the radio activity on bridge channels.
For information on the Carrier Busy test, refer to the Performing a Carrier Busy Test section of Configuring Radio Settings.
For information on RF interference, refer to the Radio Frequency Interference section of Intermittent Connectivity Issues in Wireless Bridges.
- WLAN does not work if there is a configuration mismatch between the wireless devices in a WLAN network. Parameters to check include Wired Equivalent Privacy (WEP) keys, Service Set Identifier (SSID), Channel used for WLAN, Data Rates, and Distance.
For more information, refer to the Software Configuration Problems section of Troubleshooting Problems Affecting Radio Frequency Communication.
- Always ensure that the latest version of the firmware and drivers for all of the devices in the WLAN network are used.
The latest Cisco IOS and drivers can be downloaded from the Wireless Downloads section of Cisco.com.
- Check the physical setup of devices and the wireless network. Check for loose connections, damaged cables, or cable runs shared with power cables.
- Ensure that the antennas are properly aligned. When directional antennas are used to communicate between two bridges, the antennas must be manually aligned for proper operation.
For more information on antenna alignment, refer to the Basic Antenna Alignment section of Antenna Basics.
- Use the Link test to check radio communication with a remote device.
The Link test sends data packets of a specified size to a destination radio, receives the same data packet back from the destination, verifies the data, and provides status information. For more information on this test, refer to the Performing a Link Test section of Antenna Basics.
Problem Type
No signal
Products
Workgroup bridges
Access point
Bridge
WLAN adapters (wireless card) / ACU (Aironet Client Utility)
Base Station
What can you ping?
Cannot ping peer
Link Status Meter Test Result
No signal
