LWAPPs Dropping Clients with Only Moderate Load

Unanswered Question
Apr 25th, 2012

Hope someone has an answer to this problem, as it's been plaguing me for some time.

In my district, I have 11 schools running many LWAPPs and WAPs, connected to a single WLC and managed by WCS.

Only the 4 LWAPPs in the administration building experience the following issue:

When about 8-10 WiFi devices are present on one AP in the bulding (which usually happens during a meeting), all APs show a "Load Threshold Violation Error" and start dropping some clients intermittently and refusing to connect some new clients. There doesn't seem to be a pattern as to what sort of clients drop, or which ones can connect or re-connect. My WLC is on the same subnet as these LWAPPs since it is in the same building.

If I reboot the APs, this sets things back to normal for a while, but eventually the APs will show the same errors and the same connection problems occur. I have tried adding an LWAPP to our Boardroom, which is generally where users are located when the WiFi drops. For a while, this solved the problem, but it has since returned even with the additional LWAPP.

Currently, I have all four LWAPPs in this building set to AP Mode H-REAP, as I do in my other schools. I understand this is normally bad practice; when your APs are on the same subnet as your WLC, generally those APs should be set to AP Mode Local. However, in my case, Local causes more drops and connection failures than H-REAP, so H-REAP is the closest thing I have to a "solution" to the problem.

I have checked the logs on my WLC and in WCS, and do not see any error messages besides the load threshold violations. I have tried increasing client count, and adjusting interference settings, but nothing seems to help.

All LWAPPs are AIR-LAP1131G-A-K9 on IOS12.4(18a)JA2. WLC is Model 4404 on 5.2.193.0 firmware.

Any ideas? I will be glad to post logs or provide other info as needed.

I have this problem too.
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Leo Laohoo Wed, 04/25/2012 - 15:31
WLC is Model 4404 on 5.2.193.0 firmware.

Before we go any further, I have just one thing to say.  And it is this:  Stay as far away as possible from WLC firmware 5.X code.

Sorry to say this (to Cisco developers) but I would like to call the 5.X as the "lost cause" version as it has more bugs than features.

Upgrade your firmware to 7.0.230.0 and observe if you find any improvements.  Please do not forget to upgrade the bootstraps as well.

mpscabraln Thu, 04/26/2012 - 10:35

leolaohoo wrote:

WLC is Model 4404 on 5.2.193.0 firmware.

Before we go any further, I have just one thing to say.  And it is this:  Stay as far away as possible from WLC firmware 5.X code.

Sorry to say this (to Cisco developers) but I would like to call the 5.X as the "lost cause" version as it has more bugs than features.

Upgrade your firmware to 7.0.230.0 and observe if you find any improvements.  Please do not forget to upgrade the bootstraps as well.

Honestly, I wouldn't mind doing this, but downloading new firmware requires a valid Cisco support account, which we do not have, and don't have the budget to acquire right now either.

Upgrading is definitely on my wish/to-do list but for now a solution that doesn't require firmware updates would be great.

wesleyterry Thu, 04/26/2012 - 13:19

The error you are referencing about load threshold is only a message. Its a paramater that says "after X users are on an AP, send the warning message".  It in itself does not do anything to clients.

If you want to troubleshoot this, then you should find a client in question and reproduce this problem while on the WLC you do a "debug client "

Out of curiousity, do you have load-balancing enabled?  Thats the most likely cause for when you have clients disconnecting from wireless....     If Client Load-Balancing is enabled, I'm fairly sure in WLC 5.2 code it was a fix number, instead of a sliding scale....

Again, the client debug will help you see what is happening to your clients, if the WLC is at fault.

If you see "status 17" anywhere in the debug  then your clients are being load-balanced and you need to turn that off.....

mpscabraln Mon, 04/30/2012 - 14:19

We do not have Aggressive Load Balancing enabled, if that’s what you’re talking about.

When I can get to run some tests, I will try the debug client command and see what that brings up.

Thanks for your input!

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Posted April 25, 2012 at 9:55 AM
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