Troubleshooting guide

5-28
ATM and Layer 3 Switch Router Troubleshooting Guide
OL-1969-02
Chapter 5 Troubleshooting Switch Router ATM Interface Connections
Troubleshooting OC-3c, OC-12c, and OC-48c Interfaces
Follow these steps to troubleshoot an OC-3c, OC-12c, or OC-48c physical interface:
Step 1 Use the show interfaces atm card/subcard/port command to check the configuration.
Switch# show interfaces atm 11/0/0
ATM11/0/0 is down, line protocol is down
Hardware is oc48c
MTU 4470 bytes, sub MTU 4470, BW 2488320 Kbit, DLY 0 usec, rely 0/255, load 15
Encapsulation ATM, loopback not set, keepalive not supported
Last input never, output never, output hang never
Last clearing of "show interface" counters never
Queueing strategy: fifo
Output queue 0/40, 0 drops; input queue 0/75, 0 drops
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
0 packets input, 0 bytes, 0 no buffer
Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
0 packets output, 0 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets
0 output buffer failures, 0 output buffers swapped out
Switch#
Step 2 Check the ATM field to see whether the interface is up.
If down, check for the following:
• Disconnected or faulty cabling—Check cables.
• Hardware failure—Swap hardware.
If administratively down, the interface has been administratively taken down. Use the no shutdown
interface configuration command to reenable the interface.
Step 3 Check the line protocol field to see whether the status is up.
If the interface is 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.
• 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.
• Hardware might have failed. Try swapping the interface module.
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 CRC field. The presence of many CRC errors, but not many collisions, indicates excessive
noise. If the number of errors is too high, check the cables for damage. If you are using UTP cable, make
sure you are using category 5 cables and not another type, such as category 3.