I have been trying to diagnoise this problem for a while (slow 10Gb connection). I thought it might be firmware or settings related(MTU). How ever while looking through some SNMP stuff I discovered that the switch (Quanta LB4M) is reporting the speed as much lower then 10Gb. Why is it doing this? The switch is attached to a Dell PE2950 using a DAC. The Dell is reporting a 10Gb link, as is the switch in the port config section. Only in the SNMP am I seeing the 4.3 Gbps, and in real world testing that is where were hitting a wall, about at 550MB's. This was with raw packet generators and testing file transfer speeds with RAM disk on each system.