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How to change the radio frequency (channel) on Cisco Aironet devices

 

 

Introduction

 

 

To change the frequency (channel) on Cisco Aironet devices, refer to these documents:

 

 

The actual frequency allowed depends on the regulatory body that controls the radio spectrum in the location where the unit is used. If you leave the setting at auto, when it starts, the unit samples all allowed frequencies and attempts to pick a frequency that is not in use. This setting is only allowed on the root unit, which is in charge of setting up the radio cell.

 

To set a frequency, connect to the bridge, go to the menu, and select Main > Configuration > Radio > Frequency.

 

In the Frequency window, type a value for the frequency, or leave the setting as auto.

 

 

The default channel setting for the access point radios is least congested; at startup, the access point scans for and selects the least-congested channel. For most consistent performance after a site survey, however, we recommend that you assign a static channel setting for each access point. The channel settings on your access point correspond to the frequencies available in your regulatory domain. See "Channels and Antenna Settings," for the frequencies allowed in your domain.

 

Each 2.4-GHz channel covers 22 MHz. The bandwidth for channels 1, 6, and 11 does not overlap, so you can set up multiple access points in the same vicinity without causing interference. Both 802.11b and 802.11g 2.4-GHz radios use the same channels and frequencies.

The 5-GHz radio operates on eight channels from 5180 to 5320 MHz. Each channel covers 20 MHz, and the bandwidth for the channels overlaps slightly. For best performance, use channels that are not adjacent (44 and 46, for example) for radios that are close to each other.

 

 

The default channel setting for the wireless device radios is least congested; at startup, the wireless device scans for and selects the least-congested channel. For the most consistent performance after a site survey, however, we recommend that you assign a static channel setting for each access point.

 

Note In places where RF interference might be causing clients to occasionally get disconnected from the wireless network, setting the wireless interface to run on a different channel, such as channel 1 (2412), might avoid the interference.


The channel settings on the wireless device correspond to the frequencies available in your regulatory domain. See the access point's hardware installation guide for the frequencies allowed in your domain.

 

Note Cisco Aironet CB20A client radios sometimes fail to associate to the AIR-RM21A radio module because the CB20A client does not support all the channels supported by the AIR-RM21A radio module. The default channel setting for the AIR-RM21A radio module, least congested, often results in the access point settling on one of these frequencies that the CB20A client radio does not support: channel 149 (5745 GHz), channel 153 (5765 GHz), channel 157 (5785 GHz), and channel 161 (5805 GHz). To avoid this problem, set the channel on the AIR-RM21A radio module to one of the channels supported by the CB20A client.


Each 2.4-GHz channel covers 22 MHz. The bandwidth for channels 1, 6, and 11 does not overlap, so you can set up multiple access points in the same vicinity without causing interference. Both 802.11b and 802.11g 2.4-GHz radios use the same channels and frequencies.

The 5-GHz radio operates on eight channels from 5180 to 5320 MHz. Each channel covers 20 MHz, and the bandwidth for the channels overlaps slightly. For best performance, use channels that are not adjacent (44 and 46, for example) for radios that are close to each other.

 

Note Too many access points in the same vicinity creates radio congestion that can reduce throughput. A careful site survey can determine the best placement of access points for maximum radio coverage and throughput.

 

Problem Type

Configure / Configuration issues

 

Products

Access point

Bridge

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