Linux forwarding Win XP hosts VERY slowly

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I've built an advanced rotuign appliance, and I'm having 2

outstanding> problems, that I'm being to think are related to the linux ip/netfilter

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stack, choking on XP traffic (possiblity XP-SP2) hosts that are

on the LAN.

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I'm running 2.4.30 at the moment.

The 2 problems I'm seeing:

1) Forwarded traffic (most notably web) is VERY slow with XP

clients.>

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Example: Saw this last 2 nights ago: Appliance has a linksys

Wifi bridge

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attached to a NIC. Customer browses through the appliance to the

Linksys> config page. It moves like molasses. He browse to the local Zope hosted

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made page. Slow as hell. I unplug his machine, and plug my linux

laptop> into same switch port. Linksys and Zope pages load adn reload instantly.

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Plug his machine in....slow again.

2) Zope serves user interface pages for the appliance. Zope has been locking solid for no apparent reason, but only when and Windows

host is

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attached. The trick is SOME windows machine don't seem to cause

a problem.

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Example:
I worked with a unit for 3 days using a customers XP desktop.

Not a hiccup.

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My partner came in and attached to the network and starting

connect to our

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appliance with his XP laptop. Within 15 minutes Zope was hung.

I would strongly suspect the XP box has a b0rken TCP stack happening. One
thing that some windows systems will do is flat out ignore the TCP MTU/window
size settings on the network, especially if you've a) set them up for modem
dialup b) installed anything that is supposed to automatically improve your
internet speed c) hard wired (EVER) the MTU settings. I had a win2k box that
had this sort of issue once, and even though it was at that time set to use
default settings for MTU/max recieve window and the like, I had to completely
uninstall the tcp stack, the network card driver, all modem bits etc and
reinstall em from scratch to get it to behave normally. For the record,
Ethereal dumps of the communications CLEARLY show that the windows box is
using bad MTU settings and bad TCP window sizes, if this is the case.

I *still* believe that there are settings left on that box (still in use these
days) that cause issues periodically. Cant wait to get it out of service
later in May.

Hmm ... Grant T has the same drift (darn ... mail filters are busy tonight --
must be lots of spam in this round ... took Grants mail 6 minutes to get into
the box after yours....)

Alistair Tonner

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I'm really lost. ANY ideas out there?