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Cisco ONS 15454 SDH Troubleshooting Guide, R5.0
July 2005
Chapter 1 General Troubleshooting
1.2.7 Perform an XC Loopback on a Source-Node STM-N VC (East to West) Carrying an Electrical Circuit
Step 7 Complete the “1.2.7 Perform an XC Loopback on a Source-Node STM-N VC (East to West) Carrying
an Electrical Circuit” procedure on page 1-32.
1.2.7 Perform an XC Loopback on a Source-Node STM-N VC (East to West)
Carrying an Electrical Circuit
The XC loopback tests whether any problem exists on the circuit’s optical span, isolating this span from
others present on the card. It also eliminates the cross-connect card as the source of trouble for a faulty
circuit. The loopback occurs on the XC-VXL cross-connect card in a network circuit. Figure 1-17 shows
an example of an XC loopback on a source STM-N port.
Note The XC loopback on an STM-N card does not affect traffic on other circuits.
Note You can perform an XC loopback on either the circuit source working or the protect port of a 1+1
protection group.
Figure 1-17 XC Loopback on a Source STM-N Port
Complete the “Create the XC Loopback on the Source Optical Port Carrying an Electrical Circuit”
procedure on page 1-32.
Create the XC Loopback on the Source Optical Port Carrying an Electrical Circuit
Step 1 Connect an optical test set to the port you are testing:
Note Refer to the manufacturer’s instructions for detailed information about connection and setup of
the optical test set.
a. If you just completed the “1.2.6 Perform a Hairpin Test on a Destination-Node Electrical Port (East
to West)” procedure on page 1-28, leave the optical test set hooked up to the source-node port.
b. 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. The Tx and Rx terminals connect to the same port.
Step 2 Adjust the test set accordingly.
XC
Test Set
STM-Ny
STM-Nx
90601
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