For an IT enterprise sizing from few hundred's of computers to thousands, deploying operating system manually on each on of them is expensive and a time consuming process.In order to install OS on bare metal machines connected to network, Intel introduced PXE (Preboot eXecution Environment) as part of the Wired for Management framework by Intel.
Wired for Management (WfM) is a hardware-based system allowing a new computer without any software to be controlled by a master computer that could access the hard disk of the new PC to copy a program. Intel developed this system in 1990's.It can also be used for software updates and monitoring the machine remotely.
WfM included the Preboot Execution Environment (PXE) and Wake-on-LAN (WOL) standards.However WfM has now been replaced by the Intelligent Platform Management Interface standard.
The real problem for most IT managers was every time a new employee is hired, a machine in work-ready state is to be provided to the employee for doing productive work.This problem can be solved by cloning a existing machine and deploying the cloned image onto the new computer.However this needs to be automated as there can be multiple configurations with different sets of software for different category of employees (eg: software needed by a developer may not be needed by a sales person).
Real Problem : getting thousands of machines into work ready state in minimum time.
Lets try to digest how pxe boot works ?
PXE was the solution to all the above problems. Its a set of protocols used to boot a machine (without an OS) from network.So if you have a machine connected to your enterprise network , OS can be installed on it remotely over the network.
PXE uses several network protocols like Internet Protocol (IP), User Datagram Protocol (UDP), Dynamic Host Configuration Protocol (DHCP) and Trivial File Transfer Protocol (TFTP).
"Boot from Network" or a similar setting is available in BIOS of every modern computer.
A PXE client can be a server, desktop, laptop or any other machine that is equipped with PXE boot code.Once the PXE client is enabled to boot from network ,on its next boot the system can now be controlled remotely.
Entire PXE Boot Process :
PXE Boot Process with Protocol Usage :
Source : Intel pxespec document
Related Article : iPXE for Wireless Networks