From: Mohammad H. <ha...@pu...> - 2013-10-14 00:01:07
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I see, why can't you just increase iperf's window size? I had experiments where I had to set the window size in iperf to 16 MB to get an optimal bandwidth. On Sun, Oct 13, 2013 at 7:08 PM, Nik Koracek <nko...@tp...> wrote: > ** ** ** > > Hi Mohammad,**** > > ** ** > > Thanks for the reply, sorry for any confusion.**** > > ** ** > > During testing the client machine was using a default window size of 23.2 > Kbytes, while the server machine was using a default window size of 85.3 > Kbytes.**** > > ** ** > > My question is, do you know how I could get in excess of 65Mbps on a > single tcp session using the aforementioned window sizes between two > devices that had a 160ms RTT between them?**** > > ** ** > > Cheers**** > > ** ** > ------------------------------ > > *From:* Mohammad Hajjat [mailto:ha...@pu...] > *Sent:* Monday, 14 October 2013 12:18 AM > *To:* nko...@tp... > *Cc:* iperf-users > *Subject:* Re: [Iperf-users] Help understanding results from a single TCP > session**** > > ** ** > > But your server's window size isn't 25 KB, is it?**** > > Also, what is it in specific that you want to explain? I'm sorry I lost > track :P**** > > ** ** > > ** ** > > On Sun, Oct 13, 2013 at 7:46 AM, <nko...@tp...> wrote:**** > > Hi All,**** > > **** > > I was troubleshooting a throughput issue recently on an international > 300Mbps link which had a RTT of ~160ms. **** > > **** > > I have copied the output below from testing a single TCP session between > two linux servers at either endpoint.**** > > **** > > I have the output from two tests from the perspective of SERVER_A (acting > first in server mode and then in client mode). The remote server had > similar output and same window sizes i.e. when in server mode it defaulted > to 85.3 Kbytes and when in client mode defaulted to 25.3 Kbytes.**** > > **** > > ******************************************************** > > SERVER MODE (receiving connection from remote server)**** > > ******************************************************** > > **** > > [root@SERVER_A ~]# iperf -s -i 1**** > > ------------------------------------------------------------**** > > Server listening on TCP port 5001**** > > TCP window size: 85.3 KByte (default)**** > > ------------------------------------------------------------**** > > [ 4] local 192.168.1.1 port 5001 connected with 192.168.2.1 port 46326*** > * > > [ ID] Interval Transfer Bandwidth**** > > [ 4] 0.0- 1.0 sec 491 KBytes 4.02 Mbits/sec**** > > [ 4] 1.0- 2.0 sec 3.79 MBytes 31.8 Mbits/sec**** > > [ 4] 2.0- 3.0 sec 9.13 MBytes 76.6 Mbits/sec**** > > [ 4] 3.0- 4.0 sec 9.01 MBytes 75.6 Mbits/sec**** > > [ 4] 4.0- 5.0 sec 9.01 MBytes 75.6 Mbits/sec**** > > [ 4] 5.0- 6.0 sec 10.1 MBytes 84.6 Mbits/sec**** > > [ 4] 6.0- 7.0 sec 9.00 MBytes 75.5 Mbits/sec**** > > [ 4] 7.0- 8.0 sec 9.13 MBytes 76.6 Mbits/sec**** > > [ 4] 8.0- 9.0 sec 9.01 MBytes 75.6 Mbits/sec**** > > [ 4] 9.0-10.0 sec 9.02 MBytes 75.7 Mbits/sec**** > > [ 4] 0.0-10.2 sec 79.8 MBytes 65.6 Mbits/sec**** > > **** > > ******************************************************** > > CLIENT MODE (sending data to remote server)**** > > ******************************************************** > > **** > > [root@SERVER_A~]iperf -c 192.168.2.1**** > > ------------------------------------------------------------**** > > Client connecting to 192.168.2.1, TCP port 5001**** > > TCP window size: 23.2 KByte (default)**** > > ------------------------------------------------------------**** > > [ 3] local 192.168.1.1 port 56806 connected with 192.168.2.1 port 5001*** > * > > [ ID] Interval Transfer Bandwidth**** > > [ 3] 0.0-10.1 sec 116 MBytes 96.7 Mbits/sec**** > > **** > > **** > > What I did not understand is how we were getting in excess of 65 Mbps > using a single TCP session and default window size of 25.3 Kbytes.**** > > **** > > From my calculations **** > > **** > > 1000ms/160ms = 6.25 window periods**** > > 6.25 x window size (25.3Kbytes) = 158.125 Kbytes**** > > multiplied by 8 to convert into Mbps is 1.265 Mbps**** > > **** > > Any ideas on how to explain the logic behind these results given the > testing setup described above?**** > > **** > > Cheers**** > > > > ------------------------------------------------------------------------------ > October Webinars: Code for Performance > Free Intel webinars can help you accelerate application performance. > Explore tips for MPI, OpenMP, advanced profiling, and more. Get the most > from > the latest Intel processors and coprocessors. See abstracts and register > > http://pubads.g.doubleclick.net/gampad/clk?id=60134071&iu=/4140/ostg.clktrk > _______________________________________________ > Iperf-users mailing list > Ipe...@li... > https://lists.sourceforge.net/lists/listinfo/iperf-users**** > > > > **** > > ** ** > > -- **** > > *Mohammad Hajjat***** > > *Ph.D. Student***** > > *Electrical and Computer Engineering***** > > *****Purdue**** University******* > > No virus found in this message. > Checked by AVG - www.avg.com > Version: 2013.0.3408 / Virus Database: 3222/6745 - Release Date: 10/12/13* > *** > -- *Mohammad Hajjat* *Ph.D. Student* *Electrical and Computer Engineering* *Purdue University* |