Los (Oc-N) - Cisco ONS 15327 User Documentation

Chapter 14 Alarm Troubleshooting
Repeat Steps 1 to 5 for another port on the card.
Step 6
Step 7 Look for another alarm that may identify the source of the problem.
Replace the reporting card.
Step 8
Note

14.4.77 LOS (OC-N)

•
A port on the reporting OC-N card has a loss of signal (LOS) condition. An LOS occurs when a SONET
receiver detects an all-zero pattern for 10 microseconds or longer. An LOS means the upstream
transmitter has failed. If an OC-N LOS alarm is not accompanied by additional alarms, a fiber break is
usually the cause of the alarm. The condition clears when two consecutive valid frames are received.
Invisible laser radiation may be emitted from the aperture ports of the single-mode, fiber-optic
Warning
modules when no cable is connected. Avoid exposure and do not stare into open apertures.
Always use the supplied ESD wristband when working with a powered ONS 15327. Plug the wristband
Caution
cable into the ESD jack located on the lower-right outside edge of the shelf assembly.
Procedure: Clear the LOS Alarm on an OC-N Card
Verify fiber continuity to the port.
Step 1
Step 2 Verify that the correct port is in service.
Step 3 Use an optical test set to verify that a valid signal exists on the line.
Test the line as close to the receiving card as possible.
Clean the fiber:
Step 4
a.
b.
Verify that the power level of the optical signal is within the OC-N card receiver specifications.
Step 5
If there is a valid signal, replace the connector on the backplane.
Step 6
Repeat Steps 1 to 5 for another port on the card.
Step 7
Step 8 Replace the OC-N card.
June 2002
When you replace a card with an identical type of card, you do not need to make any changes to
the database.
Critical, Service-Affecting
Clean fiber according to local site practice.
If no local practice exists, use a CLETOP Real-Type or equivalent fiber-optic cleaner and follow the
instructions accompanying the product.
Cisco ONS 15327 User Documentation, R3.3
Alarm Procedures
14-57