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Cisco ONS 15327 Troubleshooting Guide, R3.4
March 2004
Chapter2 Alarm Troubleshooting
Alarm Procedures
2.6.107 LOF (OC-N)
•Critical (CR), Service Affecting (SA)
The OC-N LOF alarm occurs when a port on the reporting OC-N card has an LOF condition. LOF
indicates that the receiving ONS15327 has lost frame delineation in the incoming data. LOF occurs
when the SONET overhead loses a valid framing pattern for 3 milliseconds. Receiving two consecutive
valid A1/A2 framing patterns clears the alarm.
LOF on an OC-N card is sometimes an indication that the OC-N card reporting the alarm expects a
specific line rate and the input line rate source does not match the input line rate of the optical receiver.
Warning
Invisible laser radiation might 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 might pose an eye hazard. Use of controls or adjustments or performance of procedures other than
those specified might result in hazardous radiation exposure.
Caution Always use the supplied electrostatic discharge wristband when working with a powered ONS 15327.
Plug the wristband cable into the ESD jack located between the top high-speed and XTC slots.

Procedure: Clear the LOF (OC-N) Alarm

Step 1 Verify cabling continuity to the port reporting the alarm.
Step 2 If cabling continuity is correct, clean the fiber connectors according to site practice. If no site practice
exists, complete the procedure in the CiscoONS 15327 Procedure Guide.
Step 3 If the alarm does not clear, see the “Network Troubleshooting Tests” section on page1-2 to isolate the
fault causing the LOF alarm.
Step 4 If the alarm does not clear, or if you need assistance conducting network troubleshoo ting tests, call TAC
to report a service-affecting problem (1-800-553-2447).
2.6.108 LOP-P
•Critical (CR), Service Affecting (SA)
A Loss of Pointer Path (LOP-P) alarm indicates that the SONET path pointer in the overhead has been
lost. LOP occurs when valid H1/H2 pointer bytes are missing from the overhead. Receiving equipment
monitors the H1/H2 pointer bytes to locate the SONET payload. An LOP-P alarm occurs when eight,
nine, or ten consecutive frames do not have v alid pointer v alues. Th e alarm clears whe n three consecut ive
valid pointers are received.
The LOP-P alarm can occur when the received payload does not match the pr ovisione d payloa d. The
alarm is caused by a circuit type mismatch on the concatenation facility. For example, if an STS-1 is sent
across a circuit provisioned for STS-3c, an LOP-P alarm occurs.