Editing Preboot Execution Environment (section)

== Integration ==
[[File:DHCP vs proxyDHCP Server.png|thumb|DHCP vs proxyDHCP Server]]
The PXE Client/Server environment was designed so it can be seamlessly integrated with an already in place DHCP and TFTP server infrastructure.
This design goal presented a challenge when dealing with the classic DHCP protocol. Corporate DHCP servers are usually subject to strict policies that are designed to prevent easily adding the additional parameters and rules required to support a PXE environment. For this reason the PXE standard developed the concept of DHCP redirection or "proxyDHCP". The idea behind a proxyDHCP is to split the PXE DHCP requirements in two independently run and administered server units:

# The classic DHCP server providing IP address, IP mask, etc. ''to all booting DHCP clients''.
# The proxyDHCP server providing TFTP server IP address and name of the NBP ''only to PXE identified booting clients''.

In a DHCP plus proxyDHCP server environment<ref name="pxespec" />{{rp|18}} the PXE client initially broadcasts a single PXE DHCPDISCOVER packet and receives two complementary DHCPOFFERs; one from the regular non PXE enabled DHCP server and a second one from the proxyDHCP server. Both answers together provide the required information to allow the PXE client to continue with its booting process. This non-intrusive approach allows setting a PXE environment without touching the configuration of an already working DHCP server. The proxyDHCP service may also run on the same host as the standard DHCP service but even in this case they are both two independently run and administered applications. Since two services cannot use the same port 67/UDP on the same host, the proxyDHCP runs on port 4011/UDP. The proxyDHCP approach has proved to be extremely useful in a wide range of PXE scenarios going from corporate to home environments.