Troubleshooting guide

5-3
ATM and Layer 3 Switch Router Troubleshooting Guide
OL-1969-02
Chapter 5 Troubleshooting Switch Router ATM Interface Connections
Performing Basic Interface Checks
Step 3 Check the line protocol field to see whether the status is up.
If down, check for the following:
• The line protocol software processes might have determined that the line is unusable. Try swapping
the cable.
• The local or remote interface might be misconfigured. Check the interface configuration.
• The clocking might be misconfigured or the source interface might have failed. Refer to the
“Initially Configuring the ATM Switch Router” chapter in the
ATM Switch Router Software Configuration Guide for configuration information.
• The hardware might have failed. Try swapping the port adapter.
Step 4 Check the Encapsulation field. Confirm that the encapsulation method matches the interface type.
Step 5 Check the Last input and Last output fields. They show the number of hours, minutes, and seconds since
the last packet was successfully received or transmitted by the interface.
Step 6 Check the output hang field. It shows the number of hours, minutes, and seconds since the last reset
caused by a lengthy transmission.
Step 7 Check the cyclic redundancy check (CRC) field. The presence of many CRC errors, but not many
collisions, indicates excessive noise. If the number is too high, check the cables for damage. If you are
using unshielded twisted-pair (UTP) cables, make sure you are using category 5 cable and not another
type, such as category 3.
Note Errors and the input and output difference should not exceed 0.5 to 2.0 percent of traffic on
the interface.
If you determine that the physical interface is configured incorrectly, refer to the “Configuring
Interfaces” chapter in the ATM Switch Router Software Configuration Guide for configuration
information.
If you still have not determined the problem, continue with the next phase of basic interface
troubleshooting.
Checking Cell Rates
This procedure determines if the cell rate for an interface is correctly configured.
Use the following command to check the cell rate on a physical interface:
Command Purpose
show atm interface atm card/subcard/port Confirms the ATM interface
configuration.