BOOTP IP address assignment

BOOTP IP address assignment
9.3.4 This page will introduce BOOTP.


The bootstrap protocol (BOOTP) operates in a client-server environment and only requires a single packet exchange to obtain IP information. However, unlike RARP, BOOTP packets can include the IP address, as well as the address of a router, the address of a server, and vendor-specific information.

One problem with BOOTP, however, is that it was not designed to provide dynamic address assignment. With BOOTP, a network administrator creates a configuration file that specifies the parameters for each device. The administrator must add hosts and maintain the BOOTP database. Even though the addresses are dynamically assigned, there is still a one to one relationship between the number of IP addresses and the number of hosts. This means that for every host on the network there must be a BOOTP profile with an IP address assignment in it. No two profiles can have the same IP address. Those profiles might be used at the same time and that would mean that two hosts have the same IP address.

A device uses BOOTP to obtain an IP address when starting up. BOOTP uses UDP to carry messages. The UDP message is encapsulated in an IP packet. A computer uses BOOTP to send a broadcast IP packet using a destination IP address of all 1s, 255.255.255.255 in dotted decimal notation. A BOOTP server receives the broadcast and then sends back a broadcast. The client receives a frame and checks the MAC address. If the client finds its own MAC address in the destination address field and a broadcast in the IP destination field, it takes and stores the IP address and other information supplied in the BOOTP reply message. A step-by-step description of the process is shown in Figures through .

The next page will discuss Dynamic Host Configuration Protocol (DHCP).