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Re: ethernet comes up at wrong speed.

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 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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