Re: different results from iperf 1.7.0 to 2.0.1.
Marc,
Thank you for your email & observations, we have received them all. We
don't have an immediate answer for you, and our group's focus is mainly on
other projects right now. We *are* intent on squashing any bugs that might
be in Iperf 2+, so we appreciate your observations.
thanks again,
-Jim
At 05:48 PM 12/10/2004 +0100, Garcia Marti, Marc wrote:
>My name is Marc Garcia and I am doing my Diploma-Thesis in the
>Forschungszentrum Karlsruhe in the field of Networking in the Gridka
>project (www.gridka.de). Some days ago I sent you an Email explaining you
>some strange results within our Gigabit ethernet network and your software
>(iperf) but we received no answere.
>
>Using a Tyan motherboard chipset E7501 dual Pentium, Intel Corp. 82546EB
>Gigabit Ethernet Controller and iperf version 2.0.1 (lastest one) we
>obtained strange results in a back to back UDP test, iperf gave us around
>500Mbps with a high packet loss but under the same conditions, the
>behaviour of an TCP test was stable and close to 1Gbps. We tried the same
>test in other equipment (IBM) and both test succeeded with preety and
>stable results; no errors and both protocols were close to 1Gbps. We
>thought it was a hardware problem and after analising the device driver of
>the first group of equipments the problems still persisted; far from the
>good IBM results. Connecting the nodes back to back or via a switch did not
>change the results at all.
>
>We also observed that when using -l parameter and a bigger value than the
>default one (1700 and upper), it worked perfectly; no errors, very good
>throughput... As I told you in my last email, for us it didn't make sense
>(and still it doesn't) because the MTU of the GEthernet is set to its
>default (1500 bytes) so the TCP/IP must fragment the packet before sending
>it and then the 2 second packed won't be fullfilled so in principle the
>performance should be lower but it was not.
>
>On the other hand, we have decided to install the previous version of
>iperf (1.7.0) and it works simply great. I attach you the results we
>gathered with the hope it may clarify. We intended to use Iperf till
>version 1.7.0 as a network quality measurement tool. Since result of version
>2.0.1 is so different, could you please explain.
>
>
>Thanks a lot in advance for your time,
>
>Best Regards,
>
>Marc Garcia Marti marc.garcia --at-- iwr.fzk.de
>Forschungszentrum Karlsruhe Tel.: +497247828601
>Institute for Scientific Computing / Inst. f. Wissenschaftliches Rechnen
>Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
J. W. Ferguson (ferguson --at-- nlanr.net)
Distributed Applications Support Team
National Laboratory for Applied Network Research (NLANR)
NCSA - University of Illinois
Ph. (217) 244-1974