issues with Intel Pro/1000 and 1000baseTX

Pyun YongHyeon pyunyh at
Fri May 15 03:55:44 UTC 2009

On Thu, May 14, 2009 at 12:29:17PM -0400, James Tanis wrote:
> Bill Moran wrote:
> >In response to James Tanis <jtanis at>:
> >
> >
> >  
> >><.. snip ..>
> >>Attempting to force 1000baseTX via:
> >>
> >>ifconfig em1 media 1000baseTX mediaopt full-duplex
> >>
> >>gets me:
> >>
> >>status: no carrier
> >>
> >>After forcing the NIC to go 1000baseTX the LEDs on the backpane are both 
> >>off. I can only come to the conclusion that this is a driver issue based 
> >>on previous experience and the simple fact that the end user system is 
> >>capable of connecting at 1000baseTX. Anybody have any suggestions? I'm 
> >>hoping I'm wrong. I'd rather not do an in-place upgrade, this is a 
> >>production system and the main gateway for an entire school, when I do 
> >>not even know for sure whether this will fix the problem. It's worth it 
> >>to me though, having a 1000baseTX uplink from the switch would remove a 
> >>major bottleneck for me.
> >
> >
> >Try forcing on both ends (I assume the Procurve will allow you to do that).
> >One thing I've seen consistently is that if you force the speed/duplex on
> >one end, the other end will still try to autoneg, and will end up with
> >something stupid like 100baseT/half-duplex, or will give up and disable
> >the port.
> >  
> Ok, I just did that -- I have now attempted to force 1000baseTX on both 
> sides and on one side while the other was left auto, all three possible 
> combinations resulted in the same behavior (no carrier).
> >Also, try autoneg on both ends.  Make absolutely sure the Procurve is set
> >to autoneg.
> >  
> This was the original set up. It is also how I have it set up currently, 
> it results in 100baseTX full-duplex on both sides.
> >Replace the cable.  If the cable is marginal, autoneg will downgrade the
> >speed to ensure reliability.  Use a cable that you know will produce
> >1000baseTX because you've tested it on other systems.
> >  
> Well, I don't have any verified working cable of the appropriate length 
> so I simply switched out the cables for the main server and the backup 
> server. They are both cat6 cables crimped with cat5e modules by me. For 
> what reason (bad crimp job?) that seemed to fix the issue.

This is clear indication of cabling issue. PHY of em(4) will try
to fix all cabling problem with auto MDI/MDIX/polarity correction.
If the PHY couldn't establish a 1000baseT link with link partner it
would downshift to 100baseTX as establishing a 1000baseT link was
not possible due to cabling problems(probably missing wiring).

> Thanks for the advice!
> -- 
> James Tanis
> Technical Coordinator
> Computer Science Department
> Monsignor Donovan Catholic High School

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