Scenario 4: Span Loss Change Less Than 3 Db - Cisco NCS 2000 series Troubleshooting Manual

General Troubleshooting
Step 10
Repeat the procedures from

Scenario 4: Span Loss Change less than 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 Configuration guide). 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 Transport Planner 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.
Corrective Action for Scenario 4
SUMMARY STEPS
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
DETAILED STEPS
Step 1
Verify the alarm validity.
Step 2 For both DWDM nodes on the repaired span:
a) Double-click the card reporting the issue.
b) Click Conditions.
c) Click Retrieve and verify that an APC-OUT-OF-RANGE condition is present on an aggregate port.
Step 6, on page 73
Verify the alarm validity.
For both DWDM nodes on the repaired span:
Measure the new Span Loss value after the fiber is repaired.
Compare the Span Measurements done in
the network design with Cisco TransportPlanner.
For the two fibers belonging to the repaired span, identify the one for the W–E line direction.
Clean the LINE-RX and LINE-TX connectors of the DWDM cards that manage the fiber of the repaired
span.
If the problem persists, continue with the next step. If not, you have finished the corrective action.
If the Span Loss Change is greater than 1 dBm and the APC-OUT-OF-RANGE condition still exists,
it is mandatory to again repair the fibers to reestablish the expected span loss value.
For the two fibers belonging to the repaired span, identify the fiber for the east to west (E–W) line
direction.
Repeat the procedure from Step 6, on page 76
to Step 8, on page 73 for the E–W direction.
Step 3, on page 76
to Step 8, on page
Cisco NCS 2000 series Troubleshooting Guide, Release 11.0
Scenario 4: Span Loss Change less than 3 dB
with the Span Losses values used during
76for the E–W direction.
75