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'Unbalanced' Aironet 1250 APs

We have two Aironet 1250 APs in an office with approximately 60 wireless clients in it. Both APs and all clients are configured with the same SSID. Initially the clients are balanced evenly across the two but after a period of about one week all clients gradually become associated with just one or other of the APs (not one specific AP).

If we reboot the APs , or do a Carrier Busy Test on them, then the clients get evenly balanced once again.

I've run the Carrier Busy test and the results for both APs are between 15 to 30 % busy on all channels.

I can't see any difference in the configurations of the APs.

Have just noticed that since rebooting the APs one hour ago several clients have been removed from one AP and the following is logged in that APs event log:

"Packet to client <MAC addr> reached max retries, removing the client"

And those clients are now associated with the other AP.

So... is this just a case of interference from other 2.4GHz signals in the neighbourhood? I guess that since these are autonomous/unmanaged APs then the clients will just stay on the one AP until kicked off or logged off.

Any ideas on how to help prevent or reduce this behaviour or is this to be expected in the absence of an expensive wifi switch/controller to autobalance the clients ?


Everyone's tags (3)

'Unbalanced' Aironet 1250 APs

Well, first of all we need to emphasize then point that what AP to join is a decusion that the clinet makes and it is fully decided by the client. The question then will be: why clinets tend to join one AP, not the other.

Can I ask if the APs have some overlapping? or they are purely independent from each other (is roaming possible between two APs or not?). From your description I would answer on your behalf saying the roaming is possible and there is overlapping.

What is the channels both APs use?

I think your clinets tend to roam between APs when the current AP connection become not good enough.

for example, clients usually resides between APs (AP1 and AP2) but they are closer to AP1, so most of clients join AP1.

When the number of clients increases the RF quality for the close AP (AP1) is reduced. At some point the signal from AP2 may become better than signal from AP1 and clinets start moving to AP1.  (this is just a guess and may or may not be applied to your case).

Having different vendors having different algorithms for roaming, I suggest you start classifying problematic clients by type.

You can take an action by upgrading wireless adapter's driver on clinets.

That could improve your situation by stopping unnecessary roaming if the client did not move.

one last question: have you done any changes before the problem to appear?



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'Unbalanced' Aironet 1250 APs

At the end of the day, it is the CLIENT who decides which WAP to join.

What you can do, however not recommended, is to lower the signal of the "dominant" WAP until you get the perfect "balance".

One more thing, which radio are the majority of the clients using?  802.11a or 82.11b?