Recently upgraded a server running Xen from 3.18.44-20.el6.x86_64 to 4.9.39-29.el6.x86_64 (did a yum update so other packages would have been updated to).
Since rebooting, we randomly get "e1000e: eth0 NIC Link is Down", this happens for only a second, but since we have this interface bonded it can be enough for it to bring down the interface fail over, and then come back again, which causes packet loss.
If tried turning pcie_aspm off, flow control off, nothing seems to help. The problem seems to be worse when high traffic is being used, but also happens randomly as well.
NIC Intel Corporation 82574L Gigabit on a Supermicro box. Driver 3.2.6-k
I see lots of errors similar to these on the internet, which seem to suggest upgrading the driver, however they all have a much older version of the driver than we do, so I'm not sure thats the problem, I also don't think its the nic as it only started happening after the update.