Bootstrap Protocol

The Bootstrap Protocol (BOOTP) is a computer networking protocol used in Internet Protocol networks to automatically assign an IP address to network devices from a configuration server. The BOOTP was originally defined in published in 1985. While some parts of BOOTP have been effectively superseded by the Dynamic Host Configuration Protocol (DHCP), which adds the feature of leases, parts of BOOTP are used to provide service to the DHCP protocol. DHCP servers also provide the legacy BOOTP functionality. When a network-connected computer boots up, its IP stack broadcasts BOOTP network messages requesting an IP-address assignment. A BOOTP configuration-server replies to the request by assigning an IP address from a pool of addresses, which is preconfigured by an administrator. BOOTP is implemented using the User Datagram Protocol (UDP) for transport protocol, port number 67 is used by the (DHCP) server for receiving client-requests and port number 68 is used by the client for receiving (DHCP) server responses. BOOTP operates only on IPv4 networks. Historically, BOOTP has also been used for Unix-like diskless workstations to obtain the network location of their , in addition to the IP address assignment. Enterprises used it to roll out a pre-configured client (e.g., Windows) installation to newly installed PCs. Initially requiring the use of a boot floppy disk to establish the initial network connection, manufacturers of network cards later embedded the protocol in the BIOS of the interface cards as well as system boards with on-board network adapters, thus allowing direct network booting. The BOOTP was first defined in September 1985 in RFC 951 as a replacement for the Reverse Address Resolution Protocol RARP, published in RFC 903 in June 1984. The primary motivation for replacing RARP with BOOTP is that RARP was a link layer protocol. This made implementation difficult on many server platforms, and required that a server be present on each individual IP subnet.