Cisco ONS 15454 SDH - Perform an XC Loopback on a Destination-Node STM-N VC (West to East) Carrying an Electrical Signal

1-17
Cisco ONS 15454 SDH Troubleshooting Guide, R5.0
July 2005
Chapter 1 General Troubleshooting
1.2.3 Perform an XC Loopback on a Destination-Node STM-N VC (West to East) Carrying an Electrical Signal
Note After the active cross-connect goes into standby mode, the original standby card becomes
active and its ACT/STBY LED turns green. The former active card becomes standby and its
ACT/STBY LED turns amber.
Step 2 Resend test traffic on the loopback circuit.
Step 3 If the test set indicates a faulty circuit, the problem is probably the defective card. Return the defective
card to Cisco through the RMA process. Log into the Cisco Technical Support Website at
http://www.cisco.com/techsupport for more information or log into
http://www.cisco.com/warp/public/687/Directory/DirTAC.shtml to obtain a directory of toll-free Cisco
TAC numbers for your country.
Step 4 Complete the “Physically Replace an In-Service Cross-Connect Card” procedure on page 2-271 for the
defective card.
Step 5 Clear the hairpin circuit:
a. Click the Circuits tab.
b. Choose the hairpin circuit being tested.
c. Click Delete.
d. Click Yes in the Delete Circuits dialog box. Do not check any check boxes.
e. Confirm that the hairpin circuit is deleted form the Circuits tab list.
Step 6 Complete the “1.2.3 Perform an XC Loopback on a Destination-Node STM-N VC (West to East)
Carrying an Electrical Signal” procedure on page 1-17.
1.2.3 Perform an XC Loopback on a Destination-Node STM-N VC (West to East)
Carrying an Electrical Signal
The XC loopback tests whether any problem exists on the circuit’s optical span, isolating this span from
others present on the card. The loopback occurs on the XC-VXL cross-connect card in a network circuit.
Figure 1-13 shows an example of an XC loopback on a destination optical port. The traffic pattern looks
similar to a terminal loopback but traffic is only carried on one synchronous transport signal (STS)
instead of affecting the entire port.
Note The XC loopback on an optical 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.