Re: Network Slowdowns

[Bill Hacker <wbh@xxxxxxxxxxxxx>]

Paul Allen wrote:

> See commit relating to revision 1.258 of if_fxp.c (in FreeBSD)
>
> There is some evidence that this problem is not localized to fxp but common
> to many driver implementations.
> 	
> ----- Forwarded message from John-Mark Gurney <gurney_j@xxxxxxxxxxxxxxxxxx> -----
> Jeremy Chadwick wrote this message on Thu, Oct 05, 2006 at 09:08 -0700:
>
> > The problem in that case turned out to be duplex-related.  Both
> > boxes were auto-negotiating with the Cisco switch correctly, and
> > indeed the Cisco labelled them as auto-100/full, but as anyone who
> > is familiar with Ciscos knows, auto-negotiation on Catalysts is
> > far from reliable.  Both boxes reported auto-neg and being at 100/full
> > as well.  I ended up hard-setting the boxes to use 100/full, and
> > set the switch ports to 100/full, then rebooted both boxes (yes,
> > this is sometimes required, as driver auto-neg code is a bit tweaky);
> > voila, problem fixed.
>
>
> It appears that some ethernet drivers don't reset the phy (bring the
> link down) when changing media (duplex setting, etc)..  This means that
> if you boot w/ autoselect, and the switch autoselects to 100/full, but
> then later change it to 100/full (w/ autoselect off) it will work fine..
> but then if the cabel is pulled, or the switch resets, it attempts to
> reautoselect, but falls back to 100/half while you are still running
> 100/full...
>
> As you can imagine, it causes a very hard to track down problem since
> the time it breaks is not readily apparent...

First two whole generations of Intel 10/100 did that, *even if* set to fixed 
100-FDX.

Killer wasn't just cable move - one learned to check on that.
But they went walk-about after a power-outage on the 'SWUB' as well.

First generation just stopped talking altogether.

Switched to DEC until they were bought by Intel, then RealTek, AKA el-cheapo.

Back with Intel and Broadcom Gig-E now, and no longer a hassle.

> an ifconfig <iface> down; ifconfig <iface> up may help resolve this
> issue if you are not sure...
>
> I have just committed a patch to fxp0 to do this...

Good news!

Bill