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DFS not working

We have a setup of two AP (1242AG), one using IOS 12.3(8) and the other with IOS 12.4(3g). The idea is to configure the 5GHz radio such, that it only uses the band 1. The configuration does only allow to use dfs in this band. When the two AP have been started, both selected the same channel.

The configuration says that the channel of radio 1 is set to use dfs. Using “show controllers dot11Radio 1“ shows that channel 40 is selected but DFS is not enabled. Using “debug dot11 dot11Radio 1 dfs simulate“ also indicates that DFS is not enabled, even if the channel has been set to use dfs.

- Is there a possibility to enable dfs in the band 1?

- How can the two AP be configured, that they do not transmit on the same frequency?


Re: DFS not working

His may be because Band 1 the lower Uni band is designated for indoor use only so DFS should not be an issue the other two uni bands can be used outdoors so DFS is used/required.


Community Member

Re: DFS not working

The problem is that I do not need to use DFS, but the AP seems to require it. You can't set the channel to a specified frequency. But if I have to use DFS, I would like to be sure that two AP seeing each other do not use the same frequency. But this does not work!


Re: DFS not working


The following link should help answer your question. As you can see from the tables each channel relates to a frequency.

this is a link to the 1242 installation guide and explains channels, frequency and power levels for the different versions for the reglatory domains.

Hope this helps


Community Member

Re: DFS not working


Sorry, this does still not solve my problems. I want to use channels 36-48 in Europe. DFS is not required in this band, but typing something like "channel 36" will result in an error, telling me that only DFS can be used. But "channel DFS" does not activate DFS correctly.

AP#debug dot11 dot11Radio 1 dfs simulate

DFS not enabled for current frequency

Does anyone have explanations for this behaviour?


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