User`s guide

C-5
Modem Configurations
Before proceeding with one of these strategies, you need to determine if your server’s
modem is set up properly 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
appears at the 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 modem manual for this
information. The &Dn command appears in three places each in three of the sample
modem configuration files, see the note below.
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 shutdown and power
off. (The AIX command shutdown –F will do this.) 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 modem manual for this
information. The &Dn command appears in three places each in three of the sample
modem configuration files, see the note below.
Note: Only the following sample modem configuration files contain the &Dn command (in
three places each):
– modem_f.cfg
– modem_f0.cfg
– 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.
Recovery Strategy
The recovery strategy consists of making two calls to establish a remote session. This is the
easiest solution to implement, and allows more freedom for configuring your server’s serial
ports.
To set up a remote terminal session, dial into the Service Processor and start the system.
After the operating system is loaded and initialized, the connection will be dropped. At this
point, call the server back and the operating system will answer and offer you the login
prompt.
Prevention Strategy
The disconnect is caused by the operating system when it initializes the primary console.
The tests listed above are conducted with the remote terminal selected as the primary
console to manifest the modem’s response to DTR transitions.
• If a local ASCII terminal or a graphics console is to be a permanent part of your server,
then make one of them the primary console. Your remote terminal will no longer
experience the connection loss.
• If a local console is not a permanent part of your server, you can still assign either the
unused graphics console or the unused serial port as the primary console. This gives you
the desired seamless connection at your remote terminal.
• If you choose to use the unused serial port as the primary console, some initialization
traffic will be sent to any serial device attached to that port. As a result, that serial
device’s connection and function could be affected. These impacts may make that port
unattractive for devices other than a temporary local ASCII terminal.