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Cisco ONS 15454 Troubleshooting Guide, R8.5
November 2009
Chapter 1 General Troubleshooting
1.2.8 Perform a Terminal Loopback on a Source-Node Electrical Port (East to West)
Step 5 If the test set indicates a good circuit, the cross-connect card might have had a temporary problem that
was cleared by the side switch. Clear the XC loopback circuit:
a. Click the Circuits tab.
b. Choose the XC loopback circuit being tested.
c. Click Delete.
d. Click Yes in the Delete Circuits dialog box. Do not check any check boxes.
e. If the problem is not resolved, go to the “1.2.8 Perform a Terminal Loopback on a Source-Node
Electrical Port (East to West)” section on page 1-40.
1.2.8 Perform a Terminal Loopback on a Source-Node Electrical Port (East to
West)
The terminal loopback test is performed on the source-node electrical port in the circuit, such as a
source-node electrical port. You first create a bidirectional circuit that starts on the destination-node
electrical port and loops back on the source-node electrical port. Then you proceed with the terminal
loopback test. Completing a successful terminal loopback to a source-node electrical port verifies that
the circuit is good to the source electrical port. Figure 1-18 shows an example of a terminal loopback on
a source DS-N port.
Figure 1-18 Terminal Loopback on a Source DS-N Port
Caution Performing a loopback on an in-service circuit is service-affecting. To protect traffic, apply a lockout or
Force switch to the target loopback port. Refer to the “2.9.2 Protection Switching, Lock Initiation, and
Clearing” section on page 2-262 for basic instructions. For more information about these operations,
refer to the “Maintain the Node” chapter in the Cisco ONS 15454 Procedure Guide.
Caution In terminal loopback mode, DS3E-12 card does not support sending AIS toward the line side while
looping back traffic at the same time, though NE defaults are the same.
Note Terminal loopbacks require on-site personnel.
Destination
ONS Node
DS-N DS-NXC
Source
ONS Node
Intermediate
ONS Node
DS-N DS-NXCDS-N
Test Set
DS-N XC
115966
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