Ethtool settings not applying to CentOS eth interfaces

Allesmachine · 12-23-2009, 11:21 AM

I have an issue with a few CentOS 5.4 servers where the interfaces are set to autoneg on a gigabit full duplex line but are defaulting to 100Mb/Half duplex or some other incorrect setting. I have tried using

Code:

ethtool -s eth1 speed 1000 duplex full autoneg off

and then restart the interface however it rejects this command:

Code:

ethtool -s eth1 speed 1000 duplex full autoneg off
Cannot set new settings: Invalid argument
  not setting speed
  not setting duplex
  not setting autoneg

I can run each setting separately and it accepts the commands however it immediately returns different settings when I run

Code:

ethtool eth1

to query the current value.

I also have tried to add the following options under the networking scripts for this interface:

Code:

ETHTOOL_OPTS="speed 1000 duplex full autoneg off"

This is also rejected as being invalid. Entering in the settings one line at a time is accepted by the shell but it doesn't actually affect the interface settings when I query the device.

Also, I tried this out on the one Red Hat server we actually have a license for and pay for a limited amount of support on and it works just fine!

WTF???

Can somebody provide some insight before I get out the sledge hammer?

kbp · 12-23-2009, 03:06 PM

Gig interfaces should always be set to auto-neg.

Are there any messages in /var/log/messages related to the network interfaces ?

Have you tried replacing the network cables with known good ones ?

Are all the servers identical models ?

Allesmachine · 12-24-2009, 08:33 AM

Someone had switched the cabling on the patch bay connectors for those servers. I switched them back to CAT6 and voila! what a wild goose chase, thanks!