Troubleshooting
Symptom
Two routers are interconnected through an ISDN PRI or BRI line and they cannot ping each other.
Analysis
The causes may be:
The interface is not configured or activated.
The dial-up configuration is wrong.
The line is not well connected.
Solution
Execute the display isdn call-info command. If no prompt appears in the system, it indicates no ISDN PRI interface exists. It is necessary to configure interfaces. For a specified configuration method, see the contents about configuration of CE1/PRI interface and CT1/PRI interface in Interface module. If ISDN is not in multi-frame operation status on a PRI interface, or if ISDN is not in TEI_ASSIGNED status on a BRI interface, it might not be physically connected well.
If Q.921 debugging has been enabled, and ISDN on PRI is in multi-frame creation mode and that on BRI is in TEI configured mode, check whether dial-up configuration is correct. If the maintaining information "Q921 send data fail (L1 return failure)." is output, it indicates that the physical layer has not been activated. In this case, execute the shutdown or undo shutdown command to disable or re-enable interfaces.
Check whether the dial-up configuration is correct. If dial-up is correctly configured and the maintaining information "Q921 send data fail (L1 return failure)." is not output, the ISDN line might be not connected well.