Clients drop off network for 10-20 seconds

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Nov 12th, 2008
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Hello all,

I have an interesting problem I hope someone else has seen.

Recently, I upgraded four 1232AP's to LWAPP mode. The ap's are configured and registerd to a WiSM comtroller. The AP's are at a remote site connected via CSME fiber with 100Mb connection. The AP's are on a management vlan 192.168.51.x and the clients are associatinting and obtaining a DHCP address of 172.16.131.x. The WLAN is configured for WPA/WPA2 and AES/TKIP encryption.

There are no errors when the clients connect, although WCS is showing high amounts of FCS errors and fragment packets. Also, about every hour the client will loose its connection for 10-20 seconds. And it isn't every client at the same time. There are about 30 laptops running XP on the network and the highest client to ap density is 10 clients.

I don't see any erros on the connecting switches or router.

This thing has me baffled. Any help will be appreciated.

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krishanmistry Wed, 11/12/2008 - 09:29
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have you checked the wireless network drivers on the client laptops to ensure they are up todate, normally this is the root cause for connectivity issues with certain clients. As not alll clients drop out at the same time I am inclined to think the issue is with client drivers.

What software versions are you running on the controller and the clients#?

johnsonk1024 Wed, 11/12/2008 - 09:57
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The client drivers have been updated to the most current release. There are multiple wireless cards, but most of the drivers are from late 2007 or early-mid 2008. The laptops are also up-to-date on securit patches and updates.

The controller version is and WCS version is We are licensed for 150 AP's and using 130.

Also, because it is a recent upgrade to LWAPP on the AP's I'm leaning toward that being the cause, however, my laptop doesn't loose its connection so it appears to be a client issue.

Strange things are afoot.

jeff.kish Wed, 11/12/2008 - 11:07
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If you haven't yet, disable auto-RF. In the GUI, go to the wireless tab, click on the appropriate network, click on RRM and Auto RF. Set both channel and power dynamic selection to "On Demand" instead of Automatic. Sometimes the dynamic RRM can cause clients to drop.

johnsonk1024 Thu, 11/13/2008 - 13:01
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Today I spent 4 hours removing IPX/SPX from severl laptops and it seems to have resolved the issue. I'm still observing, but things are much more stable.

Has anyone seen this before or know if IPX is not supported across LWAPP?


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