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PPP over Modem
ROS™ v3.5 234 RS400
11.3 Troubleshooting
Problem One
My PC is calling the RuggedCom device but the call never connects.
It is important to discriminate between the call connecting (i.e. the modem answering the call)
and the PPP session connecting (i.e. successful link up and authentication). Problems with the
latter are dealt with in the next problem description.
Is the device equipped with a modem? The output of the Diagnostics menu View Product
Information command should include the modem’s identification if one is installed.
Is the modem enabled in the PPP Control menu?
Is the modem functional? Disable PPP from the PPP control menu. Enter the shell by pressing
<CTRL S> and enter “modem” and press <CR>. Reset the modem by entering <CTRL D>.
Type the command AT, the telephone number of the line the modem is on, and <CR>. The
modem should attempt to dial its own line and respond with “BUSY”.
Alternatively, re-enable PPP and monitor the PPP Statistics menu as a call is made. The menu
should show the modem detect incoming calls and go off hook.
Is the client modem programmed with the correct telephone number?
Is the client modem aborting the connection when a connect speed short of the maximum is
negotiated?
Is there a negotiation problem? The internal modem will attempt to negotiate a wide range of
connection speeds, but the client modem may be programmed to abandon the call if it does not
achieve a specific speed.
Problem Two
My modem call comes up but the PPP connection does not. What is going on?
Chances are the problem is one of authentication. View the PPP Statistics as the call is being
made. If authentication is the problem the “Authentication” parameter will briefly display “PAP
Failure” or “CHAP Failure” before retraining for the next call.
If authentication is required at the client and not at the RuggedCom device, the client may be
closing the connection.
If the client is expecting a CHAP server name different than that configured in the PPP Control
menu, it may terminate the connection.
Ultimately, it may be necessary to trace the connection activity. For a detailed description of the
PPP connection activity, turn on tracing at the PPP level.
Problem Three
I can connect to the server, but I can’t ping or telnet to it.
From the client, try to ping or telnet to the address given in the PPP Control menu “local
address” parameter.
If you can contact the server with this address but not at the management address, chances are
that your client is not configured to treat the PPP connection as its default gateway.