If a DHCP server does not already exist on the network, configure one. Refer to the Fedora Deployment Guide for details. Make sure the configuration file contains the following so that PXE booting is enabled for systems which support it:

allow booting;
allow bootp; 
class "pxeclients" {    
    match if substring(option vendor-class-identifier, 0, 9) = "PXEClient";    
    next-server <server-ip>; 
    filename "linux-install/pxelinux.0"; }

where the next-server <server-ip> should be replaced with the IP address of the tftp server.