Hi Mark,
We have not tried the latest driver yet as this would require recompiling the kernel.
We have tried a variety of cable and lengths with no joy.
We have just tried plugging the fourth interface igb3 into a switch and VLANing them off and the connection remains with no drops. So it looks like the problem is the direct connection between the two NICs.
We are running the latest firmware(BIOS) for the NICs.
