Ssm-Fail; Stu - Cisco ONS 15327 User Documentation

Chapter 14 Alarm Troubleshooting
Test the line as close to the receiving card as possible.
Step 5 Verify that the power level of the optical signal is within the optical card receiver specifications. Each
individual card section in Chapter 4 lists the receiver specifications for that card.
Step 6 Ensure that the optical transmits and receives are connected properly.
Replace the OC-N card.
Step 7

14.4.112 SSM-FAIL

•
The failed to receive synchronization status message (SSM-FAIL) alarm means the synchronization
status messaging (SSM) received by the ONS 15327 failed. The problem is external to ONS 15327. The
ONS 15327 is set up to receive SSM, but the timing source is not delivering valid SSM messages.
SSM is a SONET protocol that communicates information about the quality of the timing source. SSM
messages are carried on the S1 byte of the SONET line layer. They enable SONET devices to
automatically select the highest quality timing reference and to avoid timing loops.
Procedure: Clear the SSM-FAIL Alarm
Check that SSM is enabled on the external timing source.
Step 1
Use a test set to determine that the external timing source is delivering SSM.
Step 2

14.4.113 STU

•
The synchronization traceability unknown (STU) alarm occurs when the reporting node is timed to a
reference that does not support synchronization status messaging (SSM), but the ONS 15327 has SSM
support enabled. STU can also be raised if the timing source is sending out SSM messages but SSM is
not enabled on the ONS 15327.
SSM is a SONET protocol that communicates information about the quality of the timing source. SSM
messages are carried on the S1 byte of the SONET line layer. SSM enables SONET devices to
automatically choose the highest quality timing reference and to avoid timing loops.
Procedure: Clear the STU Condition
Click the Provisioning > Timing tabs.
Step 1
If Sync Messaging is checked, uncheck the box.
Step 2
If Sync Messaging is unchecked, check the box.
Step 3
Click Apply.
Step 4
June 2002
Minor, Non-Service-Affecting
Not Alarmed (NA) (Condition)
Cisco ONS 15327 User Documentation, R3.3
Alarm Procedures
14-79