I think this is a switch problem, but not sure what to check on the switch. I can image other machines on different switches at a normal speed but machines connected to theses two switches are more than slow.
After imaging finally finishes I test the throughput from the server to the workstation and it is good- the same as the good workstations. All of the workstation are the same. The switches are cisco catalyst 2900 series. the image is the same.

What would make the imaging so slow?
Does the imaging engine use TCP or UDP or both?
Any suggestions on where to start?