bug: CSCud65237 - IMPACTING ASCOM 802.11N HANDSET

I received 2 emails from colleagues who were hit by this bug while using the Ascom i62. 

Apparently there is a BA ack issue, as noted in the bug. Its not clear if this is only impacting Ascom as the bug id references 802.11n handsets. I asked for frame captures and will post the result when I have them. 

CSCud65237 Bug Details

Encryption key corruption on BA ack with wrong ID
Symptom: Voice disruption after roaming Conditions: Third party 11n phone This is triggered by wrong TID sent on Block ACK by client. AP is incorrectly handling the invalid frame Workaround: roam to another AP	Status   Open  (More)  Severity   2 - severe  Last Modified   In Last 3 Days  Product   Cisco IOS software  Technology   Wireless, LAN (WLAN)  1st Found-In   7.0(230.0) 7.4(1.54)  Component(s)   ap-ampdu

Comments

[Mark]

Experiencing this issue with the ascoms. the work around is to disable 802.11n on the ascoms (or on your access points if you really want to). Forcing the phones onto G\B bypasses the bug.

it presents as voice call dropouts where the call seems to stay connected but no audio can be heard on either side, it appears mostly random and occurs more often between ascom handsets in the same environment.

the bug is two fold, the ascoms generate a bad frame while roaming and the AP's do not handle it correctly.