System information

Troubleshooting Dialin Connections
Book Title
16-370
Dialin: Link Goes Down Too Soon
Symptom: After a dialin connection is established, the link goes down again too quickly.
Table 16-13 outlines the problems that might cause this symptom and describes solutions to those
problems.
Table 16-13 Dialin: Link Goes Down Too Soon
Dialin: Link Does Not Go Down or Stays Up Too Long
Symptom: After a dialin connection is established, the link stays up indefinitely or stays up for too
long in an idle state.
Table 16-14 outlines the problems that might cause this symptom and describes solutions to those
problems.
Table 16-14 Dialin: Link Does Not Go Down or Stays Up Too Long
Dialin: Poor Performance
Symptom: After a dialin connection is established, performance over the link is slow or unreliable,
often due to a high rate of data loss.
Possible Causes Suggested Actions
Dialer timeout is too short
Step 1 Use the show running-config privileged exec command to view the
router configuration. Check the value configured with the dialer
idle-timeout command.
Step 2 Increase the timeout value using the dialer idle-timeout seconds
command. The default is 120 seconds.
Dialer lists are too restrictive Step 1 Use the show running-config privileged exec command to view the
router configuration. Check the access lists referenced by dialer list
commands.
Step 2 Make sure the access lists describe all the traffic that should keep the
link active. Reconfigure the access lists to include additional traffic if
necessary.
Possible Causes Suggested Actions
Dialer lists not restrictive enough Step 1 Use the show running-config privileged exec command to view the
router configuration. Check the access lists referenced by dialer list
commands.
Step 2 Make sure the access lists do not describe traffic that should not keep
the link active. Reconfigure the access lists to exclude uninteresting
traffic if necessary.
Modems misconfigured Make sure the local and remote modems are properly configured. In
particular, both modems should be configured to disconnect on loss of DTR
(Hangup DTR).
On a Hayes-compatible modem the &D3 string is commonly used to
configure Hangup DTR on the modem, as shown in Figure 16-1. For the
exact syntax of this command, see the documentation for your modem.