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Cisco ONS 15310-CL and Cisco ONS 15310-MA Troubleshooting Guide, R7.0
Chapter1 General Troubleshooting
1.3.5 Perform a Terminal Loopback on an Intermediate-Node OC-N Port
Test the Facility Loopback Circuit
Step1 If the test set is not already sending traffic, send test traffic on the loopback circuit.
Step2 Examine the traffic received by the test set. Look for errors or any other signal information that the test
set is capable of indicating.
If the test set indicates a good circuit, no further testing is necessary with the facility loopback:
Step3 Clear the facility loopback:
a. Click the Maintenance > Optical > Loopback > Port tabs.
b. Choose None from the Loopback Type column for the port being tested.
c. Choose the appropriate state (IS,AINS; OOS,DSBLD; or OOS,MT) from the Admin State column
for the port being tested.
d. Click Apply.
e. Click Yes in the confirmation dialog box.
Step4 Clear the facility loopback circuit:
a. Click the Circuits tab.
b. Choose the loopback circuit being tested.
c. Click Delete.
d. Click Yes in the Delete Circuits dialog box.
Step5 If the test set indicates a faulty circuit, the problem might be a faulty OC-N port. Continue with the
“1.3.5 Perform a Terminal Loopback on an Intermediate-Node OC-N Port” procedure on page1-20.
1.3.5 Perform a Terminal Loopback on an Intermediate-Node OC-N Port
The terminal loopback test is performed on the node destination port in the circuit, in this example, the
destination OC-N port in the intermediate node. First, create a bidirectional circuit that starts on the node
source OC-N port and loops back on the node destination OC-N port. Then continue with the terminal
loopback test. Completing a successful terminal loopback to a node destination OC-N port verifies that
the circuit is good up to the destination OC-N port.
Caution Performing a loopback on an in-service circuit is service-affecting.

Create the Terminal Loopback on an Intermediate-Node OC-N Port

Step1 Connect an optical test set to the port you are testing:
a. If you just completed the “1.3.4 Perform a Facility Loopback on an Intermediate-Node OC-N Port”
procedure on page 1-18, leave the optical test set connected to the OC-N port in the source node.
b. If you are starting the current procedure without the optical test set connected to the OC-N port, use
appropriate cabling to attach the Tx and Rx terminals of the optical test set to the port you are
testing.
c. Adjust the test set accordingly.