Turns out it was the Cisco switch.  I replaced it with a Linksys unmanaged one and it came right up.

On Thu, Aug 16, 2012 at 2:59 PM, Bai Shen <baishen.lists@gmail.com> wrote:
I have two Dell laptops that I'm testing Cobbler on.  When I boot into linux, I can get an ip from the dhcp server running on the cobbler box.  However, it never seems to respond to the PXE request for an ip.

Is there something I can look at or setting to change?  I'm not sure why it will provide an ip under linux but not for a PXE boot.

Thanks.