DEC Digital Alpha VME 4/224 User Manual page 316

boot
The file name defined by this environment variable becomes the file name in
the outgoing BOOTP request packet. For example:
>>> set ewa0_bootp_file /var/adm/ris/ris0.alpha/vmunix.old
5. Do not specify a file name:
>>> boot ewa0
With this method, because none of the environment variables are written, the
boot process runs through both stages. Any server that receives the request
replies.
In the client-server paradigm, the way the firmware acts is affected by the
software running on the server. For example, the format of the file specification
used with TFTP depends on the server: the UNIX server requires a complete
path name. See the operating system documentation for details about server
software.
For BOOTP and TFTP to operate reliably, several network parameters, defined
as environment variables, must be configured properly. If the parameters are
misconfigured, the Internet protocols are robust enough to work intermittently,
making it hard to debug the failures. Use the following procedure to get the
software running. Note that each network interface has a complete set of
variables of its own, prefixed with the name of the interface.
The examples shown here use boot device EWA0.
1. Define the environment variable EWA0_PROTOCOLS with the name of the
boot protocol you want to enable.
You can use BOOTP (TFTP) and MOP. If this variable is not defined, all
protocols are enabled. If both strings are defined, the system tries the
first one, and if that does not work, uses the second one. For example,
the following command enables BOOTP if available, and then MOP if BOOTP
is not available:
>>> set ewa0_protocols bootp,mop
When specifying both protocols, do not use spaces between names.
2. Define the fields of the database.
Each network interface has a small database of information that is required
to operate as is on that network. The database is stored in a 300-byte
structure with the same format as a BOOTP packet. This database can
be directly read and written in binary form through the BOOTP protocol
driver. The four most important fields of the database are accessed through
the following environment variables:
13–8 Console Commands