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Modem Configuration Checklist
Troubleshooting
B-4
B.5 Modem Configuration Checklist
Most modem problems are caused by cabling mistakes or incorrect modem configuration.
However, the following items should be verified after any modem configuration, and re-
checked when there is modem trouble.
◆
The modem must be configured to disconnect immediately when DTR is de-
asserted.
◆
The modem must assert CD (or DSR, if connected) when connected to another
modem. It must not assert CD when disconnected. The modem may optionally assert
CD during outbound dialing.
◆
The modem and MSS must agree on the flow control method and baud rate scheme.
◆
The modem must not send result codes or messages to the MSS except optionally
during outgoing calls.
◆
The modem should be set to restore its configuration from non-volatile memory
when DTR is dropped.
◆
The modem should be configured to answer the phone if incoming connections are
to be supported. Generally this is done with the ats0=1 command.
◆
The modem should not be configured to answer the phone unless the MSS asserts
DTR.
◆
MSS Modem control must be enabled. Using modems on ports without modem
control enabled will lead to security problems.
◆
The MSS Autobaud feature should be enabled only when required.
B.6 Entering Commands at the Boot
Prompt
If the Boot> prompt appears on the serial console instead of the Local> prompt, one of two
things may be wrong. Either the MSS does not have enough information to boot, or the
network or flash reloading procedure has failed. If pressing the Return key does not
display a prompt, press any other key. The Boot> prompt should appear.
If the MSS does not have enough information to boot, or the network or flash reloading
procedure has failed, it will print a message to the console and wait ten seconds for serial
port activity. If it detects serial port activity, it will continue booting provided the flash is
good. However, if the user presses a key during that time period, the MSS will display the
Boot> prompt.
Note:
If you see the message “Will attempt another download in x minutes,”
press any key for the Boot> prompt.