Re: eth0 carrier wrongly seen on

[Dan Williams <dcbw redhat com>]

On Fri, 2009-01-16 at 17:56 -0500, Chuck Anderson wrote:
> On Fri, Jan 16, 2009 at 03:50:43PM -0500, Chuck Anderson wrote:
> > On Fri, Jan 16, 2009 at 03:24:23PM -0500, Dan Williams wrote:
> > > Carrier detection is driven by netlink events, so the issue could be in
> > > a number of places.  To do top-level debugging, when you plug a cable in
> > > and unplug it again, does anything happen in the log?  Failing that,
> > > we'll need to make a netlink carrier test tool to show what's happening
> > > on netlink and see if the kernel/driver is lying to us or not delivering
> > > events.
> > 
> > FYI, I've been seeing this issue too since 2.6.28.  With no cable 
> > plugged in on bootup, NM thinks the device is active.  Until I 
> > unchecked "automatically connect to this network" on my multiple 
> > static configurations, it would choose one of the static configs and 
> > set the default route to it, even though no cable was plugged in.
> > 
> > Also using e1000e on a Thinkpad T61.
> 
> nm-tool shows "Carrier Detect: yes" but ethtool eth0 shows "Link 
> detected: no".

The "Carrier Detect" is really just a capability here instead of "is
there a link/carrier now".  There are still some cards that don't
support carrier detection, though they are slowing going away.

Dan