From: Shinnazar Seytnazarov <seytnazarovsho@ynu.ac.kr>
To: ath9k-devel@lists.ath9k.org
Subject: [ath9k-devel] Transmission rate anomaly in wireshark
Date: Sun, 2 Dec 2012 11:42:20 +0900 [thread overview]
Message-ID: <002401cdd036$a6b00fa0$f4102ee0$@ac.kr> (raw)
Hi all!
These days I'm doing experiments on minstrel_ht rate adaptation performance.
I'm following rate selection mechanism by debugging it by printk messages
and wireshark on monitor station.
Surprisingly wireshark is showing different rates rather than supposed to be
according to printk messages.
To my knowledge all the MPDUs within same AMPDU should be sent at the same
rate, printk messages also confirmed it.
But however wireshark is showing different rates but with the same MCS index
and different tx flags i.e. different LGI/SGI & HT20/HT40.
Here is example output from wireshark:
- 2 AMPDU transmission is shown, from No. 876-887 and 889-897.
- According to dmesg, all the rates within both AMPDUs should be 90mbps i.e.
MCS_index = 17 and SGI/HT40
- But as we can see below, other rates are present along with 90mbps. For
example 43.3mbps belongs to MCS_index = 17 and LGI/HT20, 81mbps belongs to
MCS_index = 17 and LGI/HT40, 39mbps belongs to MCS_index = 17 and LGI/HT20.
No.
Time
Rate
Source
Destination
Protocol
Length
Info
875
8.4301
12
Tp-LinkT_0b:2c:f3 (TA)
Tp-LinkT_0b:11:d3 (RA)
802.11
58
802.11 Block Ack, Flags=........C
876
8.431964
43.3
Tp-LinkT_0b:11:d3
Tp-LinkT_0b:2c:f3
802.11
1581
QoS Data, SN=537, FN=0, Flags=.p.....TC
877
8.431969
81
Tp-LinkT_0b:11:d3
Tp-LinkT_0b:2c:f3
802.11
1581
QoS Data, SN=538, FN=0, Flags=.p.....TC
878
8.431971
81
Tp-LinkT_0b:11:d3
Tp-LinkT_0b:2c:f3
802.11
1581
QoS Data, SN=539, FN=0, Flags=.p.....TC
879
8.431973
43.3
Tp-LinkT_0b:11:d3
Tp-LinkT_0b:2c:f3
802.11
1581
QoS Data, SN=540, FN=0, Flags=.p.....TC
880
8.431975
39
Tp-LinkT_0b:11:d3
Tp-LinkT_0b:2c:f3
802.11
1581
QoS Data, SN=541, FN=0, Flags=.p.....TC
881
8.431976
43.3
Tp-LinkT_0b:11:d3
Tp-LinkT_0b:2c:f3
802.11
1581
QoS Data, SN=542, FN=0, Flags=.p.....TC
882
8.431978
43.3
Tp-LinkT_0b:11:d3
Tp-LinkT_0b:2c:f3
802.11
1581
QoS Data, SN=543, FN=0, Flags=.p.....TC
883
8.43198
90
Tp-LinkT_0b:11:d3
Tp-LinkT_0b:2c:f3
802.11
1581
QoS Data, SN=544, FN=0, Flags=.p.....TC
884
8.431982
39
Tp-LinkT_0b:11:d3
Tp-LinkT_0b:2c:f3
802.11
1581
QoS Data, SN=545, FN=0, Flags=.p.....TC
885
8.431983
81
Tp-LinkT_0b:11:d3
Tp-LinkT_0b:2c:f3
802.11
1581
QoS Data, SN=546, FN=0, Flags=.p.....TC
886
8.431985
90
Tp-LinkT_0b:11:d3
Tp-LinkT_0b:2c:f3
802.11
1581
QoS Data, SN=547, FN=0, Flags=.p.....TC
887
8.431987
90
Tp-LinkT_0b:11:d3
Tp-LinkT_0b:2c:f3
802.11
1581
QoS Data, SN=548, FN=0, Flags=.p.....TC
888
8.431988
12
Tp-LinkT_0b:2c:f3 (TA)
Tp-LinkT_0b:11:d3 (RA)
802.11
58
802.11 Block Ack, Flags=........C
889
8.433481
43.3
Tp-LinkT_0b:11:d3
Tp-LinkT_0b:2c:f3
802.11
1581
QoS Data, SN=549, FN=0, Flags=.p.....TC
890
8.433487
39
Tp-LinkT_0b:11:d3
Tp-LinkT_0b:2c:f3
802.11
1581
QoS Data, SN=550, FN=0, Flags=.p.....TC
891
8.433489
81
Tp-LinkT_0b:11:d3
Tp-LinkT_0b:2c:f3
802.11
1581
QoS Data, SN=551, FN=0, Flags=.p.....TC
892
8.433491
81
Tp-LinkT_0b:11:d3
Tp-LinkT_0b:2c:f3
802.11
1581
QoS Data, SN=552, FN=0, Flags=.p.....TC
893
8.433492
39
Tp-LinkT_0b:11:d3
Tp-LinkT_0b:2c:f3
802.11
1581
QoS Data, SN=553, FN=0, Flags=.p.....TC
894
8.433495
43.3
Tp-LinkT_0b:11:d3
Tp-LinkT_0b:2c:f3
802.11
1581
QoS Data, SN=554, FN=0, Flags=.p.....TC
895
8.433496
39
Tp-LinkT_0b:11:d3
Tp-LinkT_0b:2c:f3
802.11
1581
QoS Data, SN=555, FN=0, Flags=.p.....TC
896
8.433498
43.3
Tp-LinkT_0b:11:d3
Tp-LinkT_0b:2c:f3
802.11
1581
QoS Data, SN=556, FN=0, Flags=.p.....TC
897
8.4335
90
Tp-LinkT_0b:11:d3
Tp-LinkT_0b:2c:f3
802.11
1581
QoS Data, SN=557, FN=0, Flags=.p.....TC
898
8.433501
12
Tp-LinkT_0b:2c:f3 (TA)
Tp-LinkT_0b:11:d3 (RA)
802.11
58
802.11 Block Ack, Flags=........C
Now I'm thinking that either monitor station or wireshark is failing to
properly decode the rate specific tx_flags. Is that true?
Is there anyone who experienced the same anomaly?
Any answer or opinion is appreciated!
My hardware: tp-link TL-WDN4800
Driver: compat-wireless-3.5.4-1
============================
Shinnazar
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