Re: FYI... PPP, Network errors, packet loss - FIX

Subject: Re: FYI... PPP, Network errors, packet loss - FIX
From: Leonard Chung (
Date: Tue May 29 2001 - 23:08:11 MDT

Hi Tim,

Thanks for the tip. It looks like it solved all of my ethernet problems on
my 7200. I'll keep an eye on it to see whether any more problems occur.

Perhaps there should be a FAQ article about this?

Thanks again,


At 02:47 AM 5/29/2001, you wrote:
>Hi all,
>In reading some of the email of the last couple of weeks I think some of
>you may be coming up against a problem I have found with every distro on
>most platforms since version 6.0 Redhat etc....
>The problem exist because certain RFC1323 TCPIP variables are turned on
>by default and shouldn't be unless your network is 100Mb or faster !
>I had terrible troubles with modem and other slow speed links until I
>changed these settings. Some of my associates also had their troubles
>fixed with transfering large files over a normal ethernet network after
>changing these settings.
>I have verified that Redhat Linux version 6.x thru 7.1 on Intel, Alpha &
>Sparc exhibit this fault and YDL 1.2.1 - I would guess that other
>distros based around Redhat would have the same problems but I haven't
>had time to try any other different distros although NetBSD 1.5 is next
>on my list - just to be different.
>There is also a growing problem with the new ECN (Explicit Congestion
>Notification RFC 2481) setting it that it seems that a lot of
>implementations are broken and thus cause connections to not build at
>all. Once I find the article I was reading on it and the associated
>variables involved i'll post the fix to the list.
>Anyway.... here is how to fix the RFC1323 problems...
>To enable an immediate fix, do the following:
>echo 0 > /proc/sys/net/ipv4/tcp_sack
>echo 0 > /proc/sys/net/ipv4/tcp_timestamps
>echo 0 > /proc/sys/net/ipv4/tcp_window_scaling
>To ensure that these values are set on boot they need to be set in
>Here is my file with the values set.
>------begin /etc/sysctl.conf ---------
># Disables packet forwarding
>net.ipv4.ip_forward = 0
># Enables source route verification
>net.ipv4.conf.all.rp_filter = 1
># Disables automatic defragmentation (needed for masquerading, LVS)
>net.ipv4.ip_always_defrag = 0
># Disables the magic-sysrq key
>kernel.sysrq = 0
># Turn off rfc1323 stuff which stuffs connections under 10Mbs
>net.ipv4.tcp_timestamps = 0
>net.ipv4.tcp_window_scaling = 0
>net.ipv4.tcp_sack = 0
># Change a few other things to more respectable values.
>net.ipv4.tcp_fin_timeout = 2
>net.ipv4.tcp_keepalive_time = 2
>------end /etc/sysctl.conf ---------
>happy networking

Leonard Chung - <>
SETI@home - The Search for Extraterrestrial Intelligence @ home

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