Comment 6 for bug 1492146

This bug should be a top priority because people will suffer from it as soon as they reboot
their 14.04 LTS with an Intel Gigabit NIC and the "current" Utopic kernel (3.16.0-48-generic).

I had the same problem with HP ProLiant DL380e Gen8 which an Intel I350 Gigabit NIC
(Hewlett-Packard Company Ethernet 1Gb 4-port 366i Adapter)

It was hard to get a shell with 30-50% packets drop and igb driver resetting ALL NICs...
"blind-typing" on the shell and wait 1-2 minutes to get the output... of dmesg ;-)

I updated the kernel of 14.04 LTS from Utopic to Vivid and everything is working again.

Workaround is:
screen -S kernel
apt-get -y purge linux-{headers,image,image-extra}-3.16.0-48-generic
apt-get -y install linux-image-generic-lts-vivid linux-headers-generic-lts-vivid
reboot

Output of dmesg:
 igb 0000:02:00.1 em2: igb: em2 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: RX
 igb 0000:02:00.1: Detected Tx Unit Hang
   Tx Queue <3>
   TDH <0>
   TDT <0>
   next_to_use <4>
   next_to_clean <0>
 buffer_info[next_to_clean]
   time_stamp <100039540>
   next_to_watch <ffff880230b0e030>
   jiffies <1000397b6>
   desc.status <0>
igb 0000:02:00.1 em2: Reset adapter
igb 0000:02:00.2 em3: Reset adapter
igb 0000:02:00.0 em1: Reset adapter
igb 0000:02:00.0 em1: igb: em1 NIC Link is Up 100 Mbps Full Duplex, Flow Control: RX
igb 0000:02:00.1 em2: igb: em2 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: RX
igb 0000:02:00.1: Detected Tx Unit Hang