Hey,

I'm testing the following setup with the svn backfire (18/04/2011 rev 26713).  
I have an access point (192.168.1.253) configured with hostapd using the 
following configuration:

interface=wlan0
bridge=br0
driver=nl80211
auth_algs=3
debug=0
logger_syslog=-1
logger_syslog_level=2
logger_stdout=-1
logger_stdout_level=2
dump_file=/tmp/hostapd.dump
beacon_int=100
max_num_sta=255
hw_mode=a
ieee80211n=1
wmm_enabled=1
ieee80211n=1
wmm_enabled=1
ht_capab=[TX-STBC][RX-STBC12][DELAYED-BA][MAX-AMSDU-7935]
channel=48
rts_threshold=2347
fragm_threshold=2346
ssid=ntest
ctrl_interface=/var/run/hostapd
ctrl_interface_group=0
ignore_broadcast_ssid=0


With another device (192.168.1.100) I connect to this access point.  Both 
devices are ubiquitity routerstation pros with a R52n-M wireless card (AR9220). 
 Once connected it will negotiate over the block acks which ends successfully.  
Yet when I preform a ping from the client to the access point, the request is 
sent only once but the reply is sent multiple times.  All of the replies are 
acked with normal acks yet the access point appears to ignore the normal acks 
and sends out a block ack request.  Is this the normal behaviour or should this 
be reported as a bug?  The full trace can be found at 
https://euterpe.cmi.ua.ac.be/~javonts/tmp/duplicateDump.pcap .  Note that a 
bridge is used with the mac address 00:00:00:00:00:01, yet this doesn't 
influence the results. 

Related to the block ack request:

if ((info->flags & IEEE80211_TX_STAT_AMPDU_NO_BACK) &&
            (ieee80211_is_data_qos(fc))) {
            u16 tid, ssn;
            u8 *qc;

            qc = ieee80211_get_qos_ctl(hdr);
            tid = qc[0] & 0xf;
            ssn = ((le16_to_cpu(hdr->seq_ctrl) + 0x10)
                        & IEEE80211_SCTL_SEQ);
            ieee80211_send_bar(sta->sdata, hdr->addr1,
                       tid, ssn);
        }

This is the part where a BAR (Block Ack Request) is sent.  Why is the ssn added 
with 1?  Should the request not include the current ssn?  In case of one 
packet, the response is a all zero ack bitmap because a block ack of a ssn 
which is not even been used, is requested.

Regards
Jeroen
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