The BOOTP uses UDP/IP. It is run when the machine boots. The protocol allows diskless machines to discover their IP address and the address of the server host. Additionally name of the file to be loaded from memory and executed is also supplied to the machine. This protocol is an improvement over RARP which has the follwing limitations:
- Networks which do not have a broadcast method can't support RARP as it uses the broadcast method of the MAC layer underneath the IP layer.
- RARP is heavily dependent on the MAC protocol.
- RARP just supplies the IP address corresponding to a MAC address It doesn't support respond with any more data.
- RARP uses the computer hardware's address to identify the machine and hence cannot be used in networks that dynamically assign hardware addresses.
Events in BOOTP
- The Client broadcasts its MAC address (or other unique hardware identity number) asking for help in booting.
- The BOOTP Server responds with the data that specifies how the Client should be configured (pre-configured for the specific client)
Note: BOOTP doesn't use the MAC layer broadcast but uses UDP/IP.
Configuration Information
The important informations provided are:
- IP address
- IP address of the default router for that particular subnet
- Subnet mask
- IP addresses of the primary and secondary nameservers
Additionaly it may also provide:
- Time offset from GMT
- The IP address of a time server
- The IP address of a boot server
- The name of a boot file (e.g. boot image for X terminals)
- The IP domain name for the client
But the problem with BOOTP is that it again can't be used for the dynamic IP's as in RARP servers.For getting dynamic IP's we use DHCP.
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