W dniu 20 kwietnia 2012 19:59 użytkownik Christian Lamparter <chunkeey@xxxxxxxxxxxxxx> napisał: > On Friday 20 April 2012 09:41:15 Janusz Dziedzic wrote: >> Hello, >> >> I am using newest compat-wireless + newest-firmware. >> Next I setup monitor mode + channel and run wireshark - I do that to >> record TCP flow on the channel. >> >> Before that I had TCP throughput about 30Mbit/s and after run >> wireshark I see TP drop - about 3Mbit/s (after setting monitor mode). >> This TP is between AP and other STA on the same channel. >> >> Should I set/check something more to not see this TP drop? > > Well, I don't know how you exactly setup the mode. But If > the monitor interface is set to PROMISC, then it's likely > that the hardware will be set into a special "sniffer" > operation mode. This mode is great if you are interested in > frames with bad PLCPs and FCS but it is not so great for > throughput because the rx filter won't filter anymore and > the tons of garbage that usually is dropped early on gets > passed to the host and on it's way it competes for FIFO > resources with the data. > > (One more thing: Isn't it possible to get the TCP flow, > from the "ethernet" (as ifconfig calls it) interface of > the wlan device as well?) > This is a scenario: AP <--> STA1 (channel 6) STA2 == carl_monitor (channel 6) This is what I can see on STA1: # iperf -c 192.168.254.1 -t 100 -i 5 ------------------------------------------------------------ Client connecting to 192.168.254.1, TCP port 5001 TCP window size: 512 KByte (default) ------------------------------------------------------------ [ 3] local 192.168.254.181 port 46048 connected with 192.168.254.1 port 5001 [ ID] Interval Transfer Bandwidth [ 3] 0.0- 5.0 sec 17.4 MBytes 29.2 Mbits/sec [ 3] 5.0-10.0 sec 19.6 MBytes 32.9 Mbits/sec [ 3] 10.0-15.0 sec 20.4 MBytes 34.2 Mbits/sec [ 3] 15.0-20.0 sec 19.8 MBytes 33.1 Mbits/sec [ 3] 20.0-25.0 sec 19.8 MBytes 33.1 Mbits/sec [ 3] 25.0-30.0 sec 19.8 MBytes 33.1 Mbits/sec [ 3] 30.0-35.0 sec 19.6 MBytes 32.9 Mbits/sec [ 3] 35.0-40.0 sec 18.1 MBytes 30.4 Mbits/sec =====> here I setup carl monitor on second PC, like this: =====> iw dev wlan0 set type monitor =====> iw dev wlan0 set freq 2437 =====> ifconfig wlan0 up [ 3] 40.0-45.0 sec 2.38 MBytes 3.98 Mbits/sec [ 3] 45.0-50.0 sec 2.50 MBytes 4.19 Mbits/sec [ 3] 50.0-55.0 sec 3.00 MBytes 5.03 Mbits/sec Seems I don't even need to start wireshark here ... and see this TP drop. BR Janusz -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
