Intel igb/e1000 driver showing dropped packets on the interface

Recently I ran into a strange issue where the Intel NIC was showing dropped packets on the interface. This particular server was having other issues (performance-ish type) so we were eager to get to the bottom of this.

Symptoms and interesting finds…

  1. ifconfig shows dropped packets only for RX
  2. The sum of rx_flow_control_xon+rx_flow_control_xoff from ethtool -S exatly matched #1 above. The count was reset at some point and we didn’t figure this out until later. Rebooting the server helped getting our minds clear and reset this.
  3. While tcpdump is running the dropped packet count would never increase.
  4. tcpdump wouldn’t show whatever was being dropped. I guess this is why they are dropped, no?

A solution, though not perfect was finally discovered. Disable BPDU/STP on the switch. The environment only had one switch so it wasn’t huge issue. On the Cisco the command was:

no spanning-tree vlan 1,100,168,216

Some interesting resources on this:

  1. Title : #477 igb driver, flow control packets being dropped?
  2. Title : Mystery RX packet drops on SLES11 SP2 every 30 sec


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