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Channel 11 Dominates

We are setting up a conference room with three access points(1200's). All three are set up using different channels(1,6 or 11). When we were doing some testing with 25 computers we noticed that whichever access point was directed to channel 11, that one had most of the associations(usually around 15 or more). Whenever we moved that channel(11) to a different access point, most of the computers would associate with that one. Is channel 11 a dominate channel or what can cause this? Is there a way to make these load balance other using mac-addresses?

Community Member

Re: Channel 11 Dominates

Hmmm... That's very fascinating. The access point selection is done by the Cisco ACU software. It is based on probe responses that it receives from nearby access points. Since the comparison is done one by one, the probe response that it gets from channel 11 will probably be evaluated last. It looks like it's becoming the winner most of the time. This is telling me that you don't have Cisco Aironet extension enabled. You can enable that feature if you only have Cisco clients. That will cause the access points to send transmitter load and number of client associations in probe responses and loadbalancing will occur. Keep in mind that signal strength is considered first(not relevant in your setup), transmitter load next, and client associations last. If an access point has traffic load higher than 10% of the access point that it is being compared to, it will not be preferred no matter how many less client associations it has.

Community Member

Re: Channel 11 Dominates

Very good answer. Your right, we do not have Cisco Aironet extensions enabled but we do only have Cisco clients. We will enable that and see what happens. Thanks


Re: Channel 11 Dominates

Might it be that channel 11 has the least amount of interfering (non-AP) signals?

It might be worth a look at the frequency allocation charts .....

It's likely to vary from country-to-country if that's the case.

Just taking a stab here, but signal quality is a prime selection factor, right?

It'll be interesting to find out.


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