A/B/G Card Continually Dropping Connection

d.beaver · ‎03-17-2005

I am troubleshooting a wireless network with approximately 16 AIR-AP1231G-A-K9 AP's and 75 client's using AIR-CB21AG-A-K9 PCMCIA cards in Toshiba and Gateway Laptops.

We are doing PEAP authentication (ACS) with WPA. There are times when the client will lose connectivity with the AP for 30 seconds and sometimes for several minutes. Then it will re-associate and continue working with ping times in the range of 1-6 ms always while it is connected.

My question is has anyone else seen anything like this with their wireless LAN's? I am wondering if there is something wrong with the client or client card? I have experimented with pulling the PCMCIA card and plugging it right back in, which usually solves the problem. I have made sure that Windows networking is not enabled and we are using the ADU utility.

Any help would be greatly appreciated.

vmoopeung · ‎03-23-2005

Verify that the device is within radio range and is associated.

http://www.cisco.com/en/US/products/hw/wireless/ps4555/products_installation_and_configuration_guide_chapter09186a0080184b62.html

http://www.cisco.com/en/US/products/hw/wireless/ps458/products_tech_note09186a00800a86d7.shtml

mkato · ‎03-24-2005

Do the logs in the AP's show anything when connectivity is lost or restored? You may want to ensure time is synchronized among all the AP's and see if any events can be correlated.

d.beaver · ‎03-25-2005

No, they don't show anything that would indicate a problem. Just normal disassocations and reassociations. What really has me baffled is the client can be sitting still and 20 feet away from the AP and still disassociate. We even went so far as to only associate one client to a given Access Point and it will still disassociate. It happens whether the computer is running an application or not.

mkato · ‎03-25-2005

Hmmm...have you scanned for rogue AP's? Also try turning off any power management-related options in the client if enabled. Other than that, I wouldn't put it past a code-related problem. If you're running the latest code in the AP's and clients, it may be time to open a TAC case...sorry I couldn't be of more help.

d.beaver · ‎03-28-2005

Well, thanks everyone for your help. It was indeed the client firmware and after updating it, the drops ceased. I wasn't aware that the A/B/G cards were so flaky with older code, but this was also one of my first encounters with that card. Anyway,we moved from 1.2.0.9 to 1.3.0.9 to fix the issue.

Thanks again for all of the input. I love this forum because people actually respond to issues.

wififofum · ‎04-24-2005

Hi,

Hey where did you get version 1.2.0.9 and 1.3.0.9 of the Firmware/ADU? The download section only lists the latest to be 1.2.0.4.

Has anyone had success returning the bad CB21AGs? They are hemming and hawing. I sent them the serial numbers.

Thanks all!

crose · ‎04-06-2005

Are you using G? If so the older CB21AG's have a known defect regarding Noise measurements that will cause connection issues at low signal levels.

I found this out by accident through my tac engineer. I also found out that cisco is clearing out their warehouses of said card and bringing in a newer version with the problem fixed. It's almost like a silent recall.

The client is associated to AP on channel 10 or 11 ( in the USA).

When operating on channels 10-13 in the 2.4GHz band, the Cisco Aironet 802.11a/b/g CardBus Wireless Adapter (CB21AG) will exhibit a higher noise floor - hence a lower signal/noise ratio - than on channels 1-9. This can provide misleading results when the CB21AG is used with diagnostics software to conduct a site survey, and may cause reduced performance or unreliable connectivity when at low signal levels.

So for all you folks that thought you where crazy, it's actually the adapter. They make you jump through some hoops to get them replaced. My general experience with this adapter is it' wasn't ready for production. It's flakey, roaming doesn't work well, and it's had aton of issues.