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 From:  Chris Buechler <cbuechler at gmail dot com>
 Cc:  m0n0wall at lists dot m0n0 dot ch
 Subject:  Re: [m0n0wall] Re: Download slows upload
 Date:  Sun, 19 Jun 2005 20:34:17 -0400
On 6/19/05, Jonny Lindholm <jonny dot lindholm at gmail dot com> wrote:
> > Jonny Lindholm wrote:
> > > Hi m0n0wall users!
> > >
> > > I'm experiencing low traffic performance on my m0n0wall 1.2b8. It
> > > seems when I max out my download the upload drops to about zero, just
> > > like it were a half duplex setting for the media speed. With 1.2b3
> > > this was not an issue, but I couldn't find that version so I
> > > downgraded to 1.11 which do not have this "error".
> >
> > What is your internet access?
> 
> 10 megabit full duplex ethernet ( 10baseT/UTP <full-duplex> )
> 
> > I had a similar problem, I had to force the wan interface to full-duplex.
> 
> I have to force full duplex also, but this error has nothing to do with that.
> 

I couldn't imagine this being a difference between versions, but
forcing full duplex on the m0n0wall side is very likely to cause a
duplex mismatch unless the other side is forced to full duplex as
well.  When autonegotiation is disabled, speed (10/100) is autosensed,
and half duplex is assumed.  So if your m0n0wall thinks the link is
full duplex, but the other device is at half, you'll run into all
kinds of late collisions that'll leave you with a link that barely
does 10% of its rated throughput (if that much).

Check your Status -> Interfaces page, under your WAN interface.  If
you're seeing any collisions, the other end must be half duplex and
you have a duplex mismatch causing the problem.

Slow uploads when downloading isn't a sign of a half duplex connection
either.  Half duplex can only send or receive at once, but that
doesn't mean you can't upload while downloading.  It just limits your
overall performance, though not by a dramatic amount.

-Chris