From mboxrd@z Thu Jan 1 00:00:00 1970 From: Shinnazar Seytnazarov Date: Sun, 2 Dec 2012 11:42:20 +0900 Subject: [ath9k-devel] Transmission rate anomaly in wireshark Message-ID: <002401cdd036$a6b00fa0$f4102ee0$@ac.kr> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: ath9k-devel@lists.ath9k.org 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 -------------- next part -------------- An HTML attachment was scrubbed... URL: http://lists.ath9k.org/pipermail/ath9k-devel/attachments/20121202/3ca25519/attachment-0001.htm -------------- next part -------------- A non-text attachment was scrubbed... Name: not available Type: image/gif Size: 530 bytes Desc: not available Url : http://lists.ath9k.org/pipermail/ath9k-devel/attachments/20121202/3ca25519/attachment-0001.gif