ethernet comes up at wrong speed.

Jerry Feldman gaf at blu.org
Sun Feb 1 15:53:25 UTC 2009


On 02/01/2009 02:43 AM, Reg Clemens wrote:
> This is an irritant with the boot o a diskless machine.
>
> I have two ethernets on one of my machines, they are both Gigabit 
> ethernet adapters, one Intel, the DLink.
>
> eth0 is the Intel, and on the ethernet with my other machines, it 
> seems to come up correctly whenever I boot.
>
> The 2nd adapter, eth1, goes ONLY to a diskless machine, which also
> has a Gigabit adapter, it 'comes up' during the diskless boot.
>
> Now SOMETIMES when you boot the diskless machine, everything works
> just fine.
>
> On other occoasions, the HOST machine shows its eth1 coming up
> at 10MBps rather than 1000MBps, and the boot hangs.  
>
> Pushing the boot button on the diskless machine again usually brings
> the HOST ethernet adapter up at 1000Bps and the boot procedes.  But one
> has usually had to go examine some log files to see what has failed,
> and thats a pain.
>
> So, WHY is the adapter coming up at the wrong speed (OK, hardware will
> do that).
> AND is there any way to tell it to ONLY try 1000Mbps, so that it doesn't
> get confused and try the wrong speed???
> Hopefully there are some options for ifcfg-eth1 (or elsewhere) that I 
> dont know about.
>
>   
First, autonegotiation is in the hardware. You can use ethtool(8) to 
change the NIC parameters. Years ago I had a similar problem with the 
DEC Alpha on my desk connecting to the switch in the lab. Try adding 
this to your ifcfg-eth1:
|This turns off autonegotiation and sets the card to 1GB.
ETHTOOL_OPTS="speed 1000 duplex full autoneg off"

Also it is important to set it to full duplex.

|

-- 
Jerry Feldman <gaf at blu.org>
Boston Linux and Unix
PGP key id: 537C5846
PGP Key fingerprint: 3D1B 8377 A3C0 A5F2 ECBB  CA3B 4607 4319 537C 5846


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