Now, you are fully set up to try to boot your PA-RISC box via network. You can follow the instructions in Section 3.6, “Effectively booting from network”.
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 state of the network connection of the 2 boxes.
Try to tcpdump while you are booting the PA-RISC box over the lan.