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Re: Mediocre TCP Performance 2.4.0 <-> Win98SE PPP

To: jamal <hadi@xxxxxxxxxx>
Subject: Re: Mediocre TCP Performance 2.4.0 <-> Win98SE PPP
From: Jordan Mendelson <jordy@xxxxxxxxxxx>
Date: Sun, 07 Jan 2001 15:44:33 -0800
Cc: netdev@xxxxxxxxxxx
Organization: Napster, Inc.
References: <Pine.GSO.4.30.0101052220500.18916-100000@shell.cyberus.ca>
Sender: owner-netdev@xxxxxxxxxxx
jamal wrote:
> 
> I am not on lk so i missed your initial post; i apologize if
> i am repeating things you might have tried out.
> It does not make sense that it works in 2.2.16 but not 2.4.0.
> 
> How reproducible is this?

100% without much difficulty. I should try it with a service other than
our own napster backend, but I can't see that making too much
difference.

> Force the MTU on linux to be 536+40.

Haven't tried that, will try on next pass with 576 and 400 just for
kicks.

> If that doesnt fix it turn off SACK.

If I'm not mistaken, I believe I did try it with various TCP options
turned off, including SACK, but I'll try again and document it this
time.

> If that doesnt fix it i would start suspecting the NIC. What NIC
> do you have on Linux? Might be alignment screw ups.

The tests were done on valinux boxes which all have eepro100's.

> If that doesnt fix it, i would start suspecting windows.
> Capture traces on both sides (windows and Linux side) for both kernels
> preferably using -w option and post the URL.

Will do.

I won't be able to get to any of this until next week because I don't
have a dialup PPP account anywhere (have to borrow another employees
account).


Jordan

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