Cisco/BSD auto-negotiation

Bill Moran wmoran at
Mon Aug 21 13:41:09 UTC 2006

In response to Javier Henderson <javier at>:

> On Aug 21, 2006, at 9:11 AM, Dave Raven wrote:
> > Hi all,
> > 	I'm currently looking into a problem with a Cisco 3640 router and a
> > FreeBSD 4.9 unit, connected via a crossover cable, that are not  
> > negotiating
> > correctly.
> >
> > If you force the media setting to full or half duplex it has constant
> > collisions on the interface, and if you let both autonegotiate the  
> > cisco
> > keeps resetting (every ~20 seconds) its network card.
> >
> > Are there known issues with this, or any known fixes?
> I've not seen this problem with my systems, all of which have Intel  
> NIC's (fxp and em), they all correctly negotiate with the Cisco gear  
> I've tested (a 2651XM and a few Catalyst switches running both IOS  
> and CatOS). I've not seen the constant negotiation you report above.  
> I've FreeBSD systems running 4.10-RELEASE, 5.5-RELEASE and 6.1- 
> RELEASE, all up to date with security patches.

While the canonical answer to this is "FreeBSD 4.9 is old, you should
upgrade and see if the problem goes away" ... I don't think that's going
to help, although you _should_ upgrade.

We have a wide range of hardware here.  Lots of Cisco switches as well
as lots of Dell switches and some off-brand.  Our experience has been
that some network hardware is garbage.  Period.  In every case where
we've had a problem similar to yours, the problem followed a particular
piece of hardware.  We've found the Dell switches are particularly
prone to this kind of problem ... i.e. no matter what make/model of
NIC we plug in to a Dell switch, we have autonegiotiate issues.
We've also found certain brands of NIC are problematic no matter what
brand of switch you plug them into.  In 90% of the cases, we've found that
forcing the duplex/speed and turning off autonegotiate fixes the problem,
in the remaining 10% of cases, we've had to replace the hardware.

Looks like you've already tried forcing the speed/duplex.  Considering the
cost of NICs these days, I'd just throw that one out and buy a replacement.

Bill Moran
Collaborative Fusion Inc.

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