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 From:  Daniele Guazzoni <daniele dot guazzoni at gcomm dot ch>
 To:  m0n0wall <m0n0wall at lists dot m0n0 dot ch>
 Subject:  Re: [m0n0wall] Massive Network Card Errors
 Date:  Wed, 28 Nov 2007 01:08:56 +0100
Last message repeated 2'000'000 times:

some people still not understand the way ethernet negotiation work so here it is once more.
Always set the two endpoints the same way, either both auto or both fixed.
Setting one endpoint to auto and the second one fixed will lead to mismatch.

There are some issues with specific hardware / drivers.
For instance some Intel cards and Cisco switches don't negotiate correctly thus forcing the use of
fixed settings.
Also some VIA Rhine chipsets will not negotiate after a setting change until you drop the link.


Chris Buechler wrote:
> On Nov 27, 2007 5:49 AM, Paul Rae <paul at impacttrainingsolutions dot co dot uk> wrote:
>> What I find more interesting is that you have collisions on both your LAN
>> and DMZ interfaces on the wrap board.
> That tells me the switches are probably configured the same, or are
> flaky in the same way with the WRAP.
> I would be willing to bet this is a duplex mismatch, everything lutzn
> mentioned points exactly to that. If you force half duplex, the
> problem most likely goes away.
> Check the configuration of the switches, if they're managed. They
> should be on auto speed and duplex, as should m0n0wall. With both
> sides on auto, assuming no switch bugs (make sure they have the latest
> firmware), this won't be an issue. If they're unmanaged switches, set
> m0n0wall to 100 Mb half duplex (*not* full) and it should work around
> the issue of failing negotiation. If you insist upon forcing speed and
> duplex on your switch (you shouldn't), make sure m0n0wall is
> configured the same as the switch.
> For more info on why:
> http://en.wikipedia.org/wiki/Autonegotiation
> http://www.sun.com/blueprints/0704/817-7526.pdf
> -Chris
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Daniele Guazzoni
Senior Network Engineer, CCNP, CCNA

Linux and AMD-x86_64 or do you still with Windows and Intel ?

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