Re: [Exim] large number of command timeouts using Exim-4.20

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Author: exim-users-admin
Date:  
To: Tony Earnshaw
CC: exim-users
Subject: Re: [Exim] large number of command timeouts using Exim-4.20
Hi Tony,

On Sun, Aug 10, 2003 at 04:55:03PM +0200, Tony Earnshaw wrote:
> OS? Two things immediately spring to mind with Linux 2.4.x - ECN and MTU
> path discovery, both settable in /proc/sys/net/ipv4 - ip_no_pmtu_disc
> and tcp_ecn. With RH 7.x for example, both can be set in rc.local.
> ip_no_pmtu_disc should be 1, tcp_ecn should be 0. They don't do much
> good, anyway, in practice.


please don't turn off path-mtu-discovery. It helps your system to
discover the optimal packet size between it and the other side of
a tcp-connection. It normally only breaks with badly configured routers
and/or firewalls and this way you are doing those idiot-admins a favour
by working around their brain-dead settings.

tcp_ecn would be a good idea if more people used it, unfortunately
(I have been told) there is non-updateable firewall and load-balancing
hardware around that doesn't like the new header-bits.

        Chris