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Cisco ONS 15310-CL and Cisco ONS 15310-MA Troubleshooting Guide, R7.0
Chapter 2 Alarm Troubleshooting
2.7.150 LOS (OCN)
The LOS (FUDC) alarm is raised if there is a user data channel (UDC) circuit created but the port is not
receiving signal input. The downstream node raises an AIS condition raised against the port transmitting
the UDC. FUDC refers to the 64-kb user data channel using the F1 byte.
Clear the LOS (FUDC) Alarm
Step 1 Using site practices, verify cable continuity to the UDC port.
Caution Always use the supplied electrostatic discharge wristband when working with a powered ONS 15310-CL
or ONS 15310-MA.
Step 2 Verify that there is a valid input signal using a test set. For instructions to do this, consult the test set
manufacturer.
Step 3 If there is a valid signal, clean the fiber according to site practice. If no site practice exists, complete the
procedure in the “Maintain the Node” chapter in the Cisco ONS 15310-CL and Cisco ONS 15310-MA
Procedure Guide.
Step 4 If the alarm does not clear, verify that the UDC is provisioned by completing the following steps:
a. At the network view, click the Provisioning > Overhead Circuits tabs.
b. If no UDC circuit exists, create one. Refer to the “Create Circuits” chapter in the
Cisco ONS 15310-CL and Cisco ONS 15310-MA Procedure Guide for procedures.
c. If a user data circuit exists (shown as User Data F1 under the Type column), check the source and
destination ports.
Step 5 If the alarm does not clear, look for and troubleshoot any other alarm that could identify the source of
the problem.
Step 6 If the alarm does not clear, log into the Technical Support Website at http://www.cisco.com/techsupport
for more information or call Cisco TAC (1-800-553-2447).
2.7.150 LOS (OCN)
Default Severity: Critical (CR), Service-Affecting (SA)
SONET Logical Object: OCN
An LOS alarm on an OC-3 or OC-12 port occurs when a SONET receiver detects an all-zero pattern for
10 microseconds or longer. An LOS alarm means the upstream transmitter has failed. If an OC-3 or
OC-12 LOS alarm is not accompanied by additional alarms, a fiber break is usually the cause of the
alarm. It clears when two consecutive valid frames are received.
Warning
Invisible laser radiation could be emitted from the end of the unterminated fiber cable or connector.
Do not stare into the beam directly with optical instruments. Viewing the laser output with certain
optical instruments (for example, eye loupes, magnifiers, and microscopes) within a distance of
100 mm could pose an eye hazard.
Statement 1056