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Cisco ONS 15454 DWDM Troubleshooting Guide, R7.0.1
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Chapter 1 General Troubleshooting
1.12.2 System Restart after a Fiber Cut
Note The total variation of the above parameter setpoint must be within approximately +/– 1 dBm
of the Span Loss Change measured in Step 3.
l. If the APC-CORRECTION-SKIPPED condition has cleared and the system has restarted properly,
we highly recommend that you complete the following procedure due to the fact that a Span Loss
value that is significantly different than the design is now present.
• Go back to the Cisco MetroPlanner tool and open the network design configuration file.
• Select Installation Mode to freeze the node layout and amplifier positioning.
• Change the span value, inserting the new Insertion Loss measured in Step 3.
• Run the Cisco MetroPlanner algorithm to validate the new design.
• If the optical result indications (power, OSNR, CD, and so on) are all green, the repair procedure
is complete. If not, log into the Technical Support Website at http://www.cisco.com/techsupport
for more information or call Cisco TAC (1 800 553-2447) in order to report a service-affecting
problem.
Note If the APC condition persists, log into the Technical Support Website at
http://www.cisco.com/techsupport for more information or call Cisco TAC (1 800 553-2447) in
order to report a service-affecting problem.
Step 9 For the two fibers belonging to the repaired span, identify the fiber for to the east to west (E–W) line
direction.
Step 10 Repeat the procedures from Step 6 to Step 8 for the E–W direction.
1.12.2.4 Scenario 4: Span Loss Change < 3 dB
In network view, both the lines that represent the span turn green after the rebuilding of the OSC optical
link and consequent restoration of the SDCC or MS-DCC. The EOC condition and LOS alarms are
cleared.
The network ALS protocol successfully completes the amplifier restart to enable OCHNC traffic
restoration along the span.
The rebuilding of circuits automatically triggers the APC check mechanism (for details, refer to the
“Network Reference” chapter of the Cisco ONS 15454 DWDM Reference Manual). The APC check
mechanism affects the optical gain of the amplifiers (primarily the OPT-PRE) and the VOA express
attenuation for the OADM cards. The APC application acts on the “suitable” cards downstream of the
repaired span (for each line direction), and attempts to compensate for the introduction of excess loss.
The APC operation is successfully completed if enough margin during the Cisco MetroPlanner network
design phase has been taken into account. If not, the adjustment done by the APC application overcomes
the range setting for a specific optical parameter in the first appropriate card along the flow and an
APC-OUT-OF-RANGE condition is raised. The condition panel of the impacted node (the ROADM in
the example) reports the APC-OUT-OF-RANGE condition and indicates the port or card to which it
applies.
To correct Scenario 4:
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