Michael Simpson wrote: > 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 > Two more things: a) make sure the router/switch isn't pegged or being changed to slower b) are your cables ok for gigabit. I know this sounds absurd, but I, personally, have changed cables, and it made the difference mark