Excessive Collisions After FC1 Installation

[Christopher A. Smith]

On Wed, Jul 28, 2004 at 12:36:11PM -0400, Scot L. Harris wrote:
> On Wed, 2004-07-28 at 11:38, Christopher A. Smith wrote:
> > I recently installed FC1 (still a little wary of FC2) on a workstation and
> > a laptop.  Both had previously been running RH 9; FC1 was installed by
> > paving the hard drive and installing from scratch.  Immediately after the
> > upgrade, I noticed a surge in Ethernet collisions and a corresponding
> > decline in network throughput and usability on both systems.  Anything
> > that involves reading or writing more than 64k or so -- e.g., NFS work,
> > web browsing, Fedora updates -- results in collisions, and network
> > activity comes to a screeching halt for several seconds.  Removing NFS all
> > together and working entirely off of local disk makes no difference.
> > (Didn't think it would, but it was worth a try.)
> 
> > 
> > Both systems had been running RH9 with the exact same hardware, and
> > collisions were never a problem.  The laptop dual-boots Windows XP Pro,
> > and its network performance is what I'd expect; there's been no observable
> > or quantifiable difference in throughput.
> > 
> > Does anyone have any ideas or suggestions on where I should look?
> > Problems with the driver (either) or its configuration?  Or is this one of
> > those "Upgrade to FC2 and call us back" situations?
> > 
> > Thanks!
> 
> I would start by verifying the duplex settings on the NIC in the FC1 box
> and the port on the switch.  mii-tool should let you check the setting
> and force it.  100Mbp connections should be set to full duplex.
> 
> I have seen some cisco switches that fight with some systems (in my
> experience SUN servers had this problem).  The auto-negotiate would not
> work as expected for some reason.  Lock down the speed and duplex
> settings on the switch and the NIC to eliminate this as a possible
> problem.

Yep, that was the problem.  The NIC was in half-duplex and is much happier
in full-duplex.

I didn't even think of that because auto-negotiation has been running fine
here for so long.  Oh well.

Thanks!

		 --------------------------------------
  Christopher A. Smith          Arlington, VA USA          chris at berzerked.org