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1.3.5 Perform a Terminal (Inward) Loopback on an Intermediate-Node Optical Ports
1.3.5 Perform a Terminal (Inward) Loopback on an Intermediate-Node Optical
Ports
In the next trouble-shooting test, you perform a terminal loopback on the intermediate-node port to
isolate whether the destination port is causing circuit trouble. In the example situation in
the terminal loopback is performed on the intermediate optical port in the circuit. You first create a
bidirectional circuit that originates on the source-node optical port and loops back on the node
destination port. You then proceed with the terminal loopback test. If you successfully complete a
terminal loopback on the node, this node is excluded from possible sources of circuit trouble.
Figure 1-24
Terminal Loopback Path to an Intermediate-Node STM-N Port
Source
ONS Node
STM-N
Test Set
STM-N cards placed in facility loopback state display an icon, shown in
Figure 1-25
Caution
Performing a loopback on an Unlocked circuit is service-affecting.
Complete the
page
Create the Terminal Loopback on Intermediate-Node Optical Ports
Connect an optical test set to the port you are testing:
Step 1
Note
a.
b.
Adjust the test set accordingly.
Step 2
Cisco ONS 15454 SDH Troubleshooting Guide, R5.0
1-52
XC
STM-N
Facility Loopback Indicator
"Create the Terminal Loopback on Intermediate-Node Optical Ports" procedure on
1-52.
Refer to the manufacturer's instructions for detailed information on connection and setup of the
optical test set.
If you just completed the
"1.3.4 Perform a Facility (Line) Loopback on an Intermediate-Node
Optical Port" procedure on page
If you are starting the current procedure without the optical test set hooked up to the source port,
use appropriate cabling to attach the Tx and Rx terminals of the optical test set to the port you are
testing. Both Tx and Rx connect to the same port.
Intermediate
ONS Node
STM-N
XC
STM-N
1-48, leave the optical test set hooked up to the source-node port.
Chapter 1
General Troubleshooting
Figure
Destination
ONS Node
STM-N
XC
STM-N
Figure
1-25.
July 2005
1-24,
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