After purchasing two dell 720 machines for a project at work, I went around setting the machines up in a very basic Pacemaker cluster. Just one problem the network interface between the machines (crossover cable) would shut itself down. But the connection to the switches would be fine.
The only way to get it going again was a ifdowm amd ifup, after scratching my head and looking through the device driver. I found out that I350 Gigabit network card support EEE, this is noted on the IGB linux driver sheet from intel found here.
Basically in order for EEE to kick in both devices need negotiate, this was happening with the two I350 connected together but the switch didn’t support this so it wasn’t happening.
option igb EEE=0 to the /etc/modprob.ed/options file the driver disabled EEE and stopped being a pain in the arse.
We will not go into if I think EEE is a good idea for server hardware ( I don’t ).