Scenario 3: 3 Dbm Less Than Span Loss Change Less Than 5 Dbm - Cisco NCS 2000 series Troubleshooting Manual

Scenario 3: 3 dBm less than Span Loss Change less than 5 dBm

• CHS Fail Low threshold must to be set to –30 dBm.
• OSC Fail Low threshold must to be set to –40 dBm.
Note If the LOS alarm is still present, 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 13 If the LOS alarm is has cleared, the system has restarted properly, but because a Span Loss value significantly different
from the design is now present, we highly recommend that you repeat the steps described in Step 11.
Scenario 3: 3 dBm less than Span Loss Change less than 5 dBm
In network view, both of the lines representing the span change to green after the rebuild of the OSC optical
link and consequent restoration of the SDCC or MS-DCC. The EOC condition and the LOS alarms are cleared.
The network ALS protocol successfully restarts the amplifiers, which enables the OCHNC traffic restoration
along the span.
The reactivation of the OCHNC circuits relating to the repaired span (the status changes from Partial to
Complete) can lead to several final conditions that depend on the network topology and node layout.
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 impacts the optical gain of the
amplifiers (primarily the OPT-PRE card) and the VOA express attenuation for the optical add/drop multiplexing
(OADM) cards. The APC application acts on the appropriate cards downstream of the repaired span (for each
line direction), and attempts to compensate for the introduction of excess loss.
Because the loss increase exceeds the maximum variation (+/3 dBm) for which APC is allowed to compensate,
an APC-CORRECTIO N-SKIPPED condition is raised by the first node along the flow detecting the event.
The condition panel of the impacted node (the ROADM, in this example) reports the
APC-CORRECTION-SKIPPED condition and indicates the port or card to which it applies.
Corrective Action for Scenario 3
SUMMARY STEPS
1.
2.
3.
4.
5.
6.
7.
8.
Cisco NCS 2000 series Troubleshooting Guide, Release 11.0
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Verify the alarm validity.
For both DWDM nodes connected to the repaired span:
Measure the new Span Loss value after the fiber has been repaired.
Compare the Span Measurements of the previous step with the Span Losses values used during the
network design with Cisco TransportPlanner.
For the two fibers belonging to the repaired span, identify the one for the W–E line direction. If the
Span Loss Change is greater than 3 dB, continue with
74.
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 Step 7. Otherwise, you are finished with the corrective
action.
If the alarm condition is still reported, we recommend that you again repair the fiber to reestablish the
expected span loss value. If this is not possible and the new value of Span Loss cannot be modified,
move to Step 8 to fix the system faulty condition.
Follow the signal flow into the network starting from the repaired fiber.
General Troubleshooting
Step 6, on page 73. If not, go to Step 9, on page