Hi, i use Senao SUB-8301 USB WLAN module (AL7230B_RF rf chip) Firmware: V1.1 (same V1.3) Kernel: 2.6.18-rc2 zd1211rw git: 83c15ac14de7a01633c07e1c68226c73f9c92421 (old but works)
While sniffing the WLAN communication between the USB WLAN module and an Access Point we found an extraordinary behaviour in handling the WLAN retries. According to the standard retried frames should preserve the WLAN sequence number and only set the retry bit. Tests with SUB-8301 USB module and a WLAN traffic analyser show that the retried frames increment the WLAN sequence number, which is in contradiction to the standard. Attached below is a snapshot of such a log: Frame WLAN Sequence=n Retry bit=0 Retry 1 WLAN Sequence=n Retry bit=1 Retry 2 WLAN Sequence=n Retry bit=1 Retry 3 WLAN Sequence=n Retry bit=1 Retry 4 WLAN Sequence=n+1 Retry bit=0 (Fault) Retry 5 WLAN Sequence=n+1 Retry bit=1 Retry 6 WLAN Sequence=n+2 Retry bit=0 (Fault) Retry 7 WLAN Sequence=n+2 Retry bit=1 Retry 8 WLAN Sequence=n+3 Retry bit=0 (Fault) Retry 9 WLAN Sequence=n+3 Retry bit=1 This behaviour violates the afore mentioned standard. We found the same behaviour under Linux and Windows OS. The faulty condition can easily be reproduced with the following procedure: 1) Generate UDP traffic to an arbitrary peer by sending packets containing unique UDP packet numbers so they can be easily identified. 2) Sniff the traffic (we used kismet). 3) Switch off the access point while transmission runs. 4) Analyze kismet logs with ethereal/wireshark. You observe above behaviour at time of switching the access point off. regard Peter ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys - and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ Zd1211-devs mailing list - http://zd1211.ath.cx/ Unsubscribe: https://lists.sourceforge.net/lists/listinfo/zd1211-devs
