On 20 March 2012 14:29, sebastian <centos at secretusenet.com> wrote: > I can not disable the auto-negotiation (eth1) on my centos 6.2 via > ethtool or /etc/sysconfig/network-scripts/ifcfg-eth1 > Autonegotiation is mandatory for 1000BASE-T as both sides have to work out which pairs they are going to use. Check: 1)cable 2)switchport if those are ok then you probably have a driver/NIC problem mike