Subject: Re: full duplex ethernet trouble
To: Charles M. Hannum <>
From: John Nemeth <>
List: tech-userlevel
Date: 07/22/2004 13:54:16
On Dec 8,  9:54pm, "Charles M. Hannum" wrote:
} On Monday 19 July 2004 02:58, John Nemeth wrote:
} > On Sep 26,  2:32pm, Martin Husemann wrote:
} > } On Thu, May 06, 2004 at 10:27:10AM -0700, Dave wrote:
} > } > Since both cards on the network were the same make and model and both
} > had } > identical /etc/ifconfig.tlp0 contents, that can't be right.  Using
} > } > "auto" in place of "100baseTX" cleared up all the problems.
} > }
} > } AFAICT NetBSD only does proper NWAY negotiation if media is set to auto.
} > } So the switch needs to be hard-wired (if it can even do that) if you
} > } hardwire the mode on the NetBSD side.
} > }
} > } This is a bug, and it should be fixed.
} >
} >      This is debatable.  The standards only define "auto" and don't say
} > what happens when you don't use it, i.e. using something other then
} > "auto" results in undefined behaviour.  Some devices will still do
} >[blah blah blah]

     A simple "[snip]" would have suffice.  Your "[blah blah blah]" is
tactless and borders on being downright rude.

} It's not really debatable.  We implemented "auto-advertisement" in two 

     If you want to be like this, then you're right, it isn't
debatable.  Since the standards only define "auto" mode, hard coding is
undefined thus it doesn't matter what NetBSD does it is correct by
definition, thus there can't be a bug.  It may not be optimal
behaviour, which would be reason enough to make changes, but it isn't a

} different projects I worked on, and complaints about duplex mismatches and 
} whatnot effectively disappeared.

     It's good that you solved your problems; however this is really
just covering up a misconfiguration.  With modern network equipment,
the only setting you can use reliably is "auto".  If you feel you must
hard code, then you need to use half duplex, since you can't reliably
hard code full duplex unless you know all the nuances of all the
equipment that you are using.  If "auto" doesn't work, then you have
broken equipment, and the drivers should be upgraded or the equipment
should be replaced.

}-- End of excerpt from "Charles M. Hannum"