iPXE is a network boot firmware. It provides a full PXE implementation enhanced with additional features such as booting from: a web server via HTTP, an iSCSI SAN, a Fibre Channel SAN via FCoE, an AoE SAN, a wireless network, a wide-area network, an Infiniband network. It controls the boot process with a script. You can use iPXE to replace the existing PXE ROM on your network card, or you can chainload into iPXE to obtain the features of iPXE without the hassle of reflashing.