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Transfer of a Modem Session
Because many modem command variations exist, the sample modem configuration files located at the end
of this appendix have been written to capture the largest number of workable modem settings.
The modem command &Dn (where n is a number) generally sets the modem response to the Data
Terminal Ready (DTR) signal from the server's serial port. The desired response is that the modem will
hold a connection while DTR is enabled, and drop the connection when DTR is released. Using this
mechanism, the server hangs up on a connection under normal conditions.
Consult your modem manual for its specific response scheme for the &Dn command.
Two strategies are available for dealing with the modem's response to DTR:
v Recovery
v Prevention
Before you use one of these strategies, determine if your server's modem is set up correctly to respond to
DTR.
With the remote terminal connected to serial port 1 and defined as the Primary Console Device, there are
two tests you can perform:
1. Will the modem drop the connection after the System initialization complete message displays at
the remote terminal?
If Yes, the modem is set up correctly.
If No, try another &Dn setting for your server's modem. See your modem manual for this information.
The &Dn command appears in three places each in three of the sample modem configuration files, as
follows:
2. Will the server's modem disconnect when the power drops? You can make this observation at the
remote terminal by commanding your server to shut down and power off. (Use the AIX command
shutdown -F.) Watch for the message NO CARRIER on your remote terminal.
If Yes, this is the correct response. The modem is set up correctly.
If No, try another &Dn setting for your server's modem. See your model manual for this information.
The &Dn command appears in three places each in three of the sample modem configuration files.
Only the following sample modem configuration files contain the &Dn command (in three places each):
v modem_f.cfg
v modem_f0.cfg
v modem_f1.cfg
If you are using modem_z.cfg or modem_z0.cfg, you cannot control DTR response. If your remote
terminal does not disconnect after logging off, you must command the remote terminal emulator to
hang up. This then breaks the connection.
Appendix E. Modem Configurations
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