Now, you are fully set up to try the boot of your PA-RISC box via network. You can follow these instructions.
If you have any trouble, start by looking at those points and then ask the PA/Linux mailing list.
Settings on the DHCP server (verify the PA-RISC MAC address is correct).
Your dhcp server is on the same physical network segment as the PA-RISC box.
The network connection of the 2 boxes.
Try to tcpdump while you are "boot lan"ing the PA-RISC box.