Weird networking problem

[Robert Brockway]

On Sun, 11 Jul 2004, Marcus Brubaker wrote:

> Thanks to everyone (especially for reading this far!) for any help or
> even positive thoughts.  I'm about ready to put my head through the wall
> on this one.

Hi Marcus.  Having bizarre connectivity issues due to "Path MTU Discovery"
has not been uncommon with DSL (although I have not seen it recently).
I actually don't think this is your issue but it should be ruled out.

The ways to try to fix this are:

1.  Lower the MTU on your end of the DSL link (drop to 296 as a test case
    and then bring it up)

2.  Turn off "Path MTU Discovery" on your end of the DSL link.

I note that you tried 2 modems and 2 OSes.  This tends to suggest another
cause, but perhaps you just happened to pick combinations of boxes &
modems that were using PMTU Discovery.

On Linux:

$cat /proc/sys/net/ipv4/ip_no_pmtu_disc

NB:
0 Indicates it is on, 1 indicates it is off.  If you do not see this file
the code is not in the kernel (thus it is off :)

Rob

-- 
Robert Brockway B.Sc. email: robert-5LEc/6Zm6xCUd8a0hrldnti2O/JbrIOy at public.gmane.org, rbrockway-cFo9iiqjkw8eIZ0/mPfg9Q at public.gmane.org
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