Symptom:

Intermittently, when a client reassociates to an access point
(within 20 seconds after having roamed away from that same
AP), the AP will fail to forward any data received from
that client, to the wired network.

Other clients can associate to that same SSID on the same AP
and work fine.

If the SSID is configured to use encryption, then, at the time
the problem is occurring, decrypt failures will be seen, when
the following debugs are enabled on the affected radio:

ap#no debug dot11 dot11radio0 print printf
ap#debug dot11 dot11radio0 trace print clients keys

Workaround:

Resetting the AP radio, or rebooting the AP, can cause the
problem temporarily to go away.

This problem is not seen in 5.2.193.0 or earlier code, nor does
it affect autonomous IOS APs.

Base Code: 6.0.182.0, 6.0.188.0, 6.0.196.0

Special Build: Following options are available:

1.     Move to 7.0.98.0 Release posted on CCO. Please note, 7.0 is a new feature release.

2.     Contact TAC to get a 6.0 Special or Beta release with fixes for the bugs below. 

3.     Wait for the CCO release of 6.0 MR3 (Maintenance Release), which is planned for July/August 2010 

The code is designed for 2100 / 4400 / 5500 / WiSM / WLC3750 / WLCM

This Software Advisory Notice is issued against all the above Wireless LAN Controller software versions due to the following bugs: