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Cisco ONS 15454 SDH Troubleshooting and Maintenance Guide, R3.3
May 2002
Chapter 2 General Troubleshooting
Identify Points of Failure on a Circuit Path
Note All loopback tests require on-site personnel.
2.2.1 Perform a Facility Loopback on a Source E3-12 Card
The facility loopback test is performed on the source card in the network circuit, in this example, the
source traffic card in the source node. Completing a successful facility loopback on this card eliminates
the cabling, the E3-12 card, and the FMEC as possible failure points. Figure 2-6 shows an example of a
facility loopback.
Figure 2-6 A facility loopback on a circuit source E3-12 card
Caution Performing a loopback on an in-service circuit is service-affecting.
Procedure: Create the Facility Loopback on the Source E3-12 Card
Step 1 Connect an electrical test set to the port you are testing.
a. Use appropriate cabling to attach the transmit (Tx) and receive (Rx) terminals of the electrical test
set to the FMEC connectors or DSx panel for the port you are testing. The transmit (Tx) and receive
(Rx) terminals connect to the same port.
b. Adjust the test set accordingly.
Step 2 Use CTC to create the facility loopback circuit on the port being tested:
a. In node view, double-click the card where you will perform the loopback.
b. Click the Maintenance > Loopback tabs.
c. Choose Facility (Line) from the Loopback Type column for the port being tested. If this is a
multiport card, select the appropriate row for the desired port.
d. Click Apply.
e. On the confirmation dialog box, click Yes.
Note It is normal for an alarm to appear during loopback setup. The alarm clears when you remove
the loopback.
ONS 15454
Source
ONS 15454
Destination
76173
E3-12 STM-NXC STM-N E3-12XC
Test Set
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