Installing ESXi 6 Using PXE - Vsphere 6

Preboot execution environment (PXE) to boot a host. Starting with vSphere 6.0, you can PXE boot the ESXi installer from a network interface on hosts with legacy BIOS or using UEFI.

ESXi is distributed in an ISO format that is designed to install to flash memory or to a local hard drive. You can extract the files and boot by using PXE. PXE uses Dynamic Host Configuration Protocol (DHCP) and Trivial File Transfer Protocol (TFTP) to boot an operating system over a network.

PXE booting requires some network infrastructure and a machine with a PXE-capable network adapter. Most machines that can run ESXi have network adapters that can PXE boot.

NOTE PXE booting with legacy BIOS firmware is possible only over IPv4. PXE booting with UEFI firmware is possible with either IPv4 or IPv6.

Overview of PXE Boot Installation Process

The interaction between the ESXi host and other servers proceeds as follows

1. The user boots the target ESXi host.
2. The target ESXi host makes a DHCP request.
3. The DHCP server responds with the IP information and the location of the TFTP server.
4. The ESXi host contacts the TFTP server and requests the file that the DHCP server specified.
5. The TFTP server sends the network boot loader, and the ESXi host executes it. The initial boot loader
6. might load additional boot loader components from the TFTP server.
7. The boot loader searches for a configuration file on the TFTP server, downloads the kernel and other
8. ESXi components from the HTTP server or the TFTP server and boots the kernel on the ESXi host.
9. The installer runs interactively or using a kickstart script, as specified in the configuration file.

Alternative Approaches to PXE Booting

Alternative approaches to PXE booting different software on different hosts are also possible, for example 

1. Configuring the DHCP server to provide different initial boot loader filenames to different hosts depending on MAC address or other criteria. See your DCHP server's documentation.
2. Approaches using iPXE as the initial bootloader with an iPXE configuration file that selects the next bootloader based on the MAC address or other criteria.