Nortel Networks 8000 - Manual (Page 434)

10 Low-speed ATM configuration
Nortel Secure Router 8000 Series
Configuration -WAN Access
10.13 Troubleshooting
This section provides troubleshooting methods for the following faults:
ATM Interface is down
Interfaces cannot successfully ping each other
PVC is down though the ATM interface is up
Pinging the peer fails though PVC is UP
Severe packet dropping and CRC errors occur though the ping succeeds
Link is not up when using IPoA or PPPoA
Packet loss caused by the deletion of some PVCs in the PVC-group
10.13.1 ATM Interface is down
Fault description
After ATM interface configuration, the interface status remains DOWN.
Fault analysis
The possible causes are:
• Incorrect interface clock configuration
• Incorrect optical fiber connection
Troubleshooting procedure
Do as follows on the routers:
Step 1 Ensure that the optical fibers are correctly plugged to the ATM interface. The two lines are
responsible for receiving and transmitting respectively, and they are not exchangeable. If they
are plugged inversely, the interface status of ATM will not be UP.
Step 2 If two routers are directly connected with each other (namely, back-to-back connection),
please check if none of the two ATM interfaces enables internal clock. By default, the routers
are configured to use internal clock. If two routers are directly connected with each other, one
of them should use internal clock with the clock master command.
—End
10.13.2 Interfaces cannot successfully ping each other
Fault description
Both physical layer and the link of two interfaces remain "UP", but they cannot successfully
ping through each other.
Fault analysis
The possible causes are:
• The clock configuration of the interface is not correct.
10-48 Nortel Networks Inc. Issue 5.3 (30 March 2009)