6Chapter 2
When booting in a network environment, BOOTP provides the terminal with the following required information: the terminal’s IP address; the IP address of the TFTP boot server; the pathname of the operating system file to be loaded using the TFTP server; the NFS directory to use for the terminal’s root file system (including NFS server IP address and pathname on that server); and a subnet mask (typically 255.255.255.0 for Class C IP addresses and 255.255.0.0 for Class B IP addresses).
For network boot, the terminal should have the following pieces of information, but they are not necessarily required for the terminal to function (depending upon your network configuration). Recommended information includes a domain name, domain name server(s) to provide
Note
Some BOOTP server implementations allow only 64 bytes of information, including identification overhead, to be sent in a reply message. If the provided information plus overhead exceeds this limit, the server will truncate the reply message to fit within the limit, with unpredictable results. SCO Openserver contains a BOOTP server with this limitation. This has been reported to SCO and may be fixed in a release of Openserver after Release 5.0.5. Because of this restriction, the T17 option (see below) may necessitate putting the terminal’s root directory off the server’s root directory (can be via a symbolic link).
To use BOOTP, you must typically make one entry per terminal, with an identifying tag and the terminal’s MAC address. Of the fields mentioned above, the only field that must be unique for each terminal is the IP address field. Therefore, if using a BOOTP server that stores data in the /etc/bootptab file, the file can take a generic approach for all other fields and use the tc entry for each terminal to refer back to that generic entry, as in the following example: