DFS on 1252

Unanswered Question
Nov 2nd, 2008

Have the requirement to be able to specify the channels that are being used with a 1252. Seem to be able to do this with a US based 1252, but the European version seems to only want to use DFS.

Is ther a quick way to disable the DFS function and specify the channel?

I have this problem too.
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pzehnder Wed, 11/05/2008 - 07:43

Blocking Channels from DFS Selection

If your regulatory domain limits the channels that you can use in specific locations--for example, indoors or outdoors--you can block groups of channels to prevent the access point from selecting them when DFS is enabled. Use this configuration interface command to block groups of channels from DFS selection:

[no] dfs band [1] [2] [3] [4] block

The 1, 2, 3, and 4 options designate blocks of channels:

•1-Specifies frequencies 5.150 to 5.250 GHz. This group of frequencies is also known as the UNII-1 band.

•2-Specifies frequencies 5.250 to 5.350 GHz. This group of frequencies is also known as the UNII-2 band.

•3-Specifies frequencies 5.470 to 5.725 GHz.

•4-Specifies frequencies 5.725 to 5.825 GHz. This group of frequencies is also known as the UNII-3 band.

This example shows how to prevent the access point from selecting frequencies 5.150 to 5.350 GHz during DFS:

ap(config-if)# dfs band 1 2 block

This example shows how to unblock frequencies 5.150 to 5.350 for DFS:

ap(config-if)# no dfs band 1 2 block

This example shows how to unblock all frequencies for DFS:

ap(config-if)# no dfs band block

pzehnder Wed, 11/05/2008 - 07:46

Configuring a Channel

Use the channel command to configure a channel. The command for the interface is modified to only allow you to select a specific channel number and to enable DFS.



Step 1

configure terminal

Enter global configuration mode.

Step 2

interface dot11radio1 dfs

Enter the configuration interface for the 802.11a radio

Step 3

channel number | dfs |band <1 - 5>}

For number, enter one of the following channels: 36, 40, 44, 48, 149, 153, 157, 161, 5180, 5200, 5220, 5240, 5745, 5765, 5785, or 5805.

Enter dfs and one of the following frequency bands to use dynamic frequency selection on the selected channel:

1-5.150 to 5.250 GHz

2-5.250 to 5.350 Ghz

3-5.470 to 5.725 GHz

4-5.725 to 5.825 GHz

If you attempt to configure a channel that may only be selected by dfs, the following message appears:

This channel number/frequency can only be used by

Dynamic Frequency Selection (DFS)

Step 4


Return to the privileged EXEC mode.

Step 5

show running-config

Verify your entries

Step 6

copy running-config startup-config

(Optional) Save your entries to the configuration file.

The following example selects channel 36 and configures it to use DFS on a frequency band 1:

ap#configure terminal

ap(config)interface dot11radio1

ap(config-if) channel 36


interlink.cco Wed, 01/21/2009 - 05:11

Don't work

aironet-1242ag-19.3#conf t

Enter configuration commands, one per line. End with CNTL/Z.


aironet-1242ag-19.3(config)#interface dot

aironet-1242ag-19.3(config)#interface dot11Radio 1



aironet-1242ag-19.3(config-if)#dfs band 2 3 block

aironet-1242ag-19.3(config-if)#dfs band 2 3 block


aironet-1242ag-19.3(config-if)#channel 36


% Invalid input detected at '^' marker.



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