Uli Kunitz wrote:
> Am 15.01.2007 um 14:59 schrieb Peter Lueg:
>> 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 ZD1211 retry register is set to 2, which gives 4 retries. (It has  
> four bits so you could ask for 2^15 retries. ;-) 

Can i increment/decrement the retries?
Which register and bit contribute the retry rate?

> I cannot explain  
> packets 4 to 9 -- this might be firmware behaviour, which we cannot  
> control. However the d80211 developers discussed to implement such  
> behaviour in the new d80211 stack. Does the 802.11 standard really  
> care, what the payload is? What prevents me to send the same UDP  
> packet three times? 

You can see this behaviour in a bad WLAN environment.
The access point saw all 802.11 frames from the client and send an ACK.
This Ack will be lost. On more than 3 retries you become an duplicated

UDP is not important. The problem is that the IP stack becomes
duplicated packets.

> On the 802.11 layer it is a new packet, because  
> it has a new sequence number.


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