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Chapter 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 name-to-IP address resolution (for other
terminals and/or computers), and gateway IP address (for allowing you to access
computers outside your subnet).
Note
NoteNote
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:
