Pre-Boot Execution Environment

PXE is one of the components of Intel's WfM specification. It allows a workstation to boot from a server on a network prior to booting the operating system on the local hard drive. A PXE-enabled workstation connects its NIC to the LAN via a jumper, which keeps the workstation connected to the network even when the power is off. Because a network administrator does not have to physically visit the specific workstation and manually boot it, operating systems and other software, such as diagnostic programs, can be loaded onto the device from a server over the network.

PXE is an acronym for Pre-Boot Execution Environment. New computers utilizing PXE are compliant with the PC99 specification. This specification for computers was developed by both Intel and Microsoft, released in 1998. The PC99 specification is much more than just network boot standards, it covers everything right down to the dopey color code used on keyboard and mouse connectors on the back of the personal computer.

PXE is an extension on DHCP. It requires both a DHCP and TFTP server on the network to which the PC is connected. A PC with a PXE enabled BIOS may boot to an operating system stored on the network server. It is more commonly used to install an operating system via the network from the remote server, but may also be used to run the remote operating system.

• Boot a diskless (no floppy, no cdrom, no harddrive) PC from an operating system via the network
• Boot an operating system installation via the network to install the OS onto the PC

The PXE protocol is a hacked combination of TFTP and DHCP. To boot from the network the PC will broadcast what is known as a DHCPDISCOVER packet with an extension. It uses UDP port 67 which is the DHCP server port. Through the process the PC is assigned an IP address and a TFTP transfer begins, the operating system data to the PC for booting.

Setting Up a PXE Boot Server

Please refer to one of the following guides:

• PXE Boot Server Configuration Using Linux (recommended)
• PXE Boot Server Configuration Using Microsoft Windows

Setting Up a PXE boot Client

This is merely an option you need to enable in BIOS. There are at least two settings in BIOS you should be aware of, the label for them depends on the BIOS of your PC. One typically refers to the enabling of PXE boot and the other is the boot device order. Remove all devices from the boot device order except for the PXE network boot option to ensure your PC is booting via the LAN.