PXE introduction and use

One 、 preface

Blackstone 2.0 Preparing clean computing resources for customers 、 In scenarios such as collecting and checking machine hardware information, you need to install one on the physical machine os, And cannot pass through the disk 、U disc 、CDROM Etc , So we can only adopt network boot installation minios, So write this article to describe PXE.

Two 、 What is? PXE

PXE(Pre-boot Execution Environment, Pre boot execution environment ) By Intel The latest technology developed by the company , Work in Client/Server Network mode of , Support workstation to download image from remote server through network , And from this support through the network to start the operating system , In the startup process , The terminal requires the server to assign IP Address , Reuse TFTP（trivial file transfer protocol） or MTFTP(multicast trivial file transfer protocol) The protocol downloads a boot package to the local memory for execution , The basic software settings of the terminal are completed by this startup software package , So as to boot the terminal operating system installed in the server in advance .

Strictly speaking ,PXE It's not an installation , It's a way of guiding . Conduct PXE A prerequisite for installation is to include a PXE Supported network cards （NIC）, That is, there must be PXE Client.PXE The protocol enables the computer to start over the network . This agreement is divided into Client End sum Server End , and PXE Client On the network card ROM in . When the computer boots ,BIOS hold PXE Client Call into memory to execute , Then from PXE Client Download the files placed at the remote end to run locally through the network . function PXE The protocol needs to be set DHCP The server and TFTP The server .DHCP The server will give PXE Client（ The host on which the system will be installed ） Allocate one IP Address , Because it's for PXE Client Distribute IP Address , So in configuration DHCP You need to add the corresponding PXE Set up . Besides , stay PXE Client Of ROM in , It already exists TFTP Client, Then it can go through TFTP The agreement reached TFTP Server Download the required files .

3、 ... and 、PXE Principle

1. bios load pxe rom after ,rom Medium pxe client First initiate dhcp request , The smart card acts as pxe server, In the verification message mac After the address is correct , return ip、tftp Server address 、 Boot file name

2. pxe client Immediately launch tftp request , Get the boot file , Such as pxelinux.0

3. Execute... In memory pxelinux.0, Specify the next step to request pxelinux.cfg

4. tftp Request and parse pxelinux.cfg, Get kernel and root file information , Respectively vmlinuz and initramfs, There are versions to distinguish

5. tftp Request kernel and root files , Boot in memory

Four 、PXE Who will do it

BIOS Set the boot entry for the next boot to take effect as Legacy perhaps Uefi Then restart the machine , Network cards provide different types of pxe rom,BIOS Of pxe The driver will load the corresponding pxe rom, And then to achieve PXE The process of .

5、 ... and 、 utilize PXE and KickStart Realize unattended installation of operating system

May refer to https://www.cnblogs.com/mchina/p/centos-pxe-kickstart-auto-install-os.html From master attempt