Re: Some questions about Iperf (fwd)
fwd
---------- Forwarded message ----------
Date: Wed, 18 Dec 2002 21:20:31 -0600 (CST)
From: Kevin Gibbs <kgibbs --at-- ncsa.uiuc.edu>
To: Daniel E. Spisak <dspisak --at-- nonmundane.org>
Subject: Re: Some questions about Iperf
Well it appears that Microsoft has set itself apart from the competition
once again. I am not sure how or why this is, but WinXP will not send more
than 100Mbit/s of data over a 100Mbit/s FULL duplex link. I have tested a
bidirectional test with 2 linux hosts and get about 180Mbit/s. I did not
do any window adjustments or any other tweaking. I use 3Com905C with the
newest drivers. Hope that answers your original question.
Kevin
On Mon, 9 Dec 2002, Daniel E. Spisak wrote:
> Curious.
>
> In my testing scenario its was one system running Windows XP and the other
> running Redhat 8.0. Both systems were 1GHz PIII systems with comparable
> I/O, RAM, NIC. I can probably get a Linux to Linux Iperf scenario setup in
> the next day or so to try this again. However I did observe the 100Mbps
> total between the two clients, albeit lopsided depending on what TCP window
> sizes were in use.
>
> I would love to hear what results you get when you do Linux to Linux.
>
> -Dan
>
> At 02:03 AM 12/9/2002 -0600, you wrote:
> >First off I did not mean to come off like I was calling you
> >ignorant or unintettigent or anything else, just
> >wanted to make sure you looked into other problems. This weekend I was
> >able to test your "exact" scenario with a couple of my machines. I have
> >3Com 905C cards which are about as good as I have used. I am not running
> >the same OS on both machines (Win XP on one, and linux the other) but the
> >test shouldn't matter. In a single direction I can get 95MB one way and
> >93.5Mb the other. However when I try to do the simultaneous bidirectional
> >I get a perfect 100Mb _TOTAL_. They are lopsided like 60 / 40 but always a
> >perfect 100. I introduced a 100Mb switch and the same thing happened but
> >with about .1-.4 Mb reduction in performance. I am not sure what is at
> >fault here, but I am beginning to think this full-duplex is not all it is
> >cracked up to be. What operating system are you running? I am sceptical of
> >my windows box because it can only push about 60Mb in a UDP test when I
> >ask it to do 100Mb. With a bidirection UDP test one side pushed 73Mb and
> >the other pushed 60Mb, but the servers only saw 87.3Mb _TOTAL_. Later this
> >week I will probably get two linux boxes up in this configuration to test
> >if windows is the problem or it is more of an ethernet protocol issue. I
> >am really leaning on the ethernet protocol right now with the perfectly
> >equal to 100Mb total tests. Let me know what you are running and if you
> >find anything out about this interesting scenario.
> >
> >By the way the machines I tested with earlier in the week had 1Gb ethernet
> >connections but are not solely mine so I got about 250Mb each way
> >bidirection or single so I am not thinking it is iperf. With UDP I was
> >able to get much closer to 400Mb each way bidirectional, but that still
> >is not total 1Gb, so it is not much help in this matter. One of the
> >machines is a quad Xeon board with the 64bit PCI and the other is a 8 way
> >SGI and I am not sure what the subsystem is. All I have in my office is a
> >10Mb network and a couple of laptops that do not perform very well so I
> >will only be able to test this at home with my computers or the shared 1Gb
> >ethernet machines.
> >
> >Kevin
>
>
>