1100 Series AP, dropping specific aironet cards

Unanswered Question

Hello,


I have 6 users on a small WLAN. The AP is an 1100 Series, and I currently have no WEP encryption enabled (nor WPA) for testing purposes. The network has worked fine for a few months without any disruption, however I now have (2) of the (6) wireless clients disconnecting intermittently. The error states: Packet to client <client MAC address> reached max retries, removing the client. It just started happening yesterday & reoccured today. One thing that is very strange is that it doesn't occur until the afternoon hours and only happens maybe once every hour or greater.


I performed a site survey using the ACU, and have "Excellent" reception from both locations. I also fired up NetStumbler to see if there are any more AP operating on that channel (9). The IOS is configured to find the least congested channel (1-11 enabled) and for "best range". I also looked at the SNR using NetStumbler, which averages -65. Upon performing a "carrier busy test" all frequencies are below 30%. I cannot figure out what is causing this. The clients experiencing this problem have a 350 and the other has a CB21ABG card.


What's really strange is one of the users has another user sitting right next to her (within 5 feet) and doesn't experience any problems at all.


I know the error points to congestion of interference, but the site survey doesn't show any other AP operating on that frequency.


What other things can I look at to find the cause? Thanks in advance.

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Anonymous (not verified) Wed, 03/26/2008 - 12:50
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In this case you can try upgrading the firmware of your Wifi-Card. Also check the any latest patch for the OS and install it. This should fix the issue.

svinay1981 Sat, 01/24/2009 - 16:00
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Hi all..


Did anyone find the "correct" fix to to this problem!? I am having the same problem with a Cisco Aironet 1121G AP and a desktop computer with the Linksys WMP54G PCI card in it. The AP shows warning messages in the event log, sometime every few minutes, sometimes every few hours, as follows:


Jan 24 17:40:41.424 S Information Interface Dot11Radio0, Station xxxx.xxxx.xxxx Associated KEY_MGMT[NONE]

Jan 24 17:40:38.918 S Information Interface Dot11Radio0, Deauthenticating Station xxxx.xxxx.xxxx Reason: Previous authentication no longer valid

Jan 24 17:40:38.918 S Warning Packet to client xxxx.xxxx.xxxx reached max retries, removing the client


Over the past week or so, I have checked into everything possible, from RF interference to updating everything on the desktop to modifying various settings on the AP's 802.11g interface (Radio0) as well as the Linksys card (matching the values for Fragment Threshold and RTS Threshold). The AP is set to WEP (with MAC authentication filter); SSID broadcast disabled. AP has latest IOS: 12.3(8)JEC2.


I am stumped! Can't seem to make those warnings go away. I am not comfortable deploying the AP without getting rid of the warnings, as clients are going to be connected to a database all day, and I dont know how those "frequent disassociations" would affect operations. Surprisingly, at the time of the warnings, I dont see the desktop wireless connection actually disconnecting and reacquiring the IP.. but I am still unsure of deploying the AP in this condition.


Any help is greatly appreciated.

Thanks much,

Vinay.


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