Comment 2 for bug 805854

Just for guys who may arrive here after searching:
1.there's kernel bug in intel 82574L e1000e driver on centos 6(MSI/MSI-X interrupts issue), we can resolve this by install kmod-e1000e package from ELrepo.org and later add pcie_aspm=off e1000e.IntMode=1,1 e1000e.InterruptThrottleRate=10000,10000 acpi=off to kernel parameters. You can read more info [URL="http://www.doxer.org/learn-linux/resolved-intel-e1000e-driver-bug-on-82574l-ethernet-controller-causing-network-blipping/"]Intel e1000e driver bug on 82574L Ethernet controller causing network blipping[/URL].
2.For the high Tx traffic, this was caused by port 53 dns flooding attack. I've resolved this by writing some iptable rules. More info here: [URL="http://www.doxer.org/learn-linux/resolved-port-53-dns-flooding-attack/"]port 53 dns flooding attack[/URL]