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Cisco ONS 15310-CL and Cisco ONS 15310-MA Troubleshooting Guide, R7.0
Chapter 1 General Troubleshooting
1.2.5 Perform a Facility Loopback on a Destination Port
Test the Facility Loopback Circuit
Step 1 If the test set is not already sending traffic, send test-set traffic on the loopback circuit.
Step 2 Examine the test traffic received by the test set. Look for errors or any other signal information that the
test set is capable of indicating.
Step 3 If the test set indicates a good circuit, no further testing is necessary with the loopback circuit.
a. Clear the facility loopback:
b. Double-click the card, then click the appropriate tab:
• Maintenance > DS1 > Loopback
• Maintenance > DS3 > Loopback
• Maintenance > EC1 > Loopback
c. Choose None from the Loopback Type column for the port being tested.
d. Choose the appropriate state (IS,AINS; OOS,DSBLD; or OOS,MT) from the Admin State column
for the port being tested.
e. Click Apply.
f. Click Yes in the confirmation dialog box.
The entire electrical circuit path has now passed its comprehensive series of loopback tests. This circuit
qualifies to carry live traffic.
Step 4 If the test set indicates a faulty circuit, the problem might be a faulty card or faulty cabling. Continue
with the “Test the Electrical Cabling” procedure on page 1-13.
Test the Electrical Cabling
Step 1 Replace the suspect cabling (the cables from the test set to the DS-1, DS-3, or EC-1 port) with a cable
known to be good.
If a cable known to be good is not available, test the suspect cable with a test set. Remove the suspect
cable from the electrical port and connect the cable to the Tx and Rx terminals of the test set. Run traffic
to determine whether the cable is good or suspect.
Step 2 Resend test traffic on the loopback circuit with a good cable installed.
Step 3 If the test set indicates a good circuit, the problem is probably the defective cable. Replace the defective
cable.
Step 4 Clear the facility loopback:
a. Double-click the card and then click the appropriate tab:
• Maintenance > DS1 > Loopback
• Maintenance > DS3 > Loopback
• Maintenance > EC1 > Loopback
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.