System information
Troubleshooting Dialin Connections
Book Title
16-354
Modem speed setting is not
locked
Step 4 When you are certain the access server or router line is configured for the
desired speed, initiate a reverse Telnet session to the modem on that line. For
more information, see the section “Establishing a Reverse Telnet Session to a
Modem” earlier in this chapter.
Step 5 Use a modem command string that includes the lock DTE speed command
for your modem. See your modem documentation for exact configuration
command syntax.
Note: The lock DTE speed command, which might also be referred to as port
rate adjust or buffered mode, is often related to the way the modem handles
error correction. This command varies widely from one modem to another.
Locking the modem speed ensures that the modem always communicates
with the Cisco access server or router at the speed configured on the Cisco
auxiliary port. If this command is not used, the modem reverts to the speed of
the data link (the telephone line) instead of communicating at the speed
configured on the access server.
Modem control is not
enabled on the access server
or router
Step 1 Use the show line exec command on the access server or router. The output
for the auxiliary port should show inout or RIisCD in the Modem column.
This indicates that modem control is enabled on the line of the access server
or router.
For an explanation of the show line output, see the “Using debug
Commands” section earlier in this chapter.
Step 2 Configure the line for modem control using the modem inout line
configuration command. Modem control is now enabled on the access server.
Example:
The following example illustrates how to configure a line for both incoming
and outgoing calls:
line 5
modem inout
Modem control is not
enabled on the access server
or router
Note: Be certain to use the modem inout command instead of the modem
ri-is-cd command while the connectivity of the modem is in question. The
latter command allows the line to accept incoming calls only. Outgoing calls
will be refused, making it impossible to establish a Telnet session with the
modem to configure it. If you want to enable the modem ri-is-cd command,
do so only after you are certain the modem is functioning correctly.
PPP authentication fails
Step 1 Use the debug ppp chap privileged exec command to see whether PPP
authentication was successful. Check the output for the phrase “Passed
authentication with remote.” If you see this output, authentication was
successful.
Step 2 If PPP authentication was not successful, verify the username and password
configured on the router. The username and password you enter must be
identical to those configured on the router.
Note: Usernames and passwords are case sensitive.
Local router not waiting
long enough to connect
Step 1 Use the show dialer exec command to see the configured dialer timeout. A
timeout value shorter than 120 seconds will not be long enough.
Step 2 Configure the local router to wait longer for the connection. Use the dialer
wait-for-carrier-time seconds command to modify the configuration. Make
sure you specify at least a 120-second timeout.
Possible Causes Suggested Actions