Specifications

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Cisco ONS 15454 Troubleshooting and Maintenance Guide
November 2001
Chapter 1 Alarm Troubleshooting
1.3.110 SSM-FAIL
• Minor, Non-service affecting
The SSM-FAIL alarm means the synchronization status messaging (SSM) received by the ONS 15454
failed. The problem is external to ONS 15454. The ONS 15454 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
Step 1 Check that SSM is enabled on the external timing source.
Step 2 Use a test set to determine that the external timing source is delivering SSM.
1.3.111 STU
• Not Alarmed (NA) (Condition)
The Synchronization Traceability Unknown alarm occurs when the reporting node is timed to a reference
that does not support synchronization status messaging (SSM), but the ONS 15454 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 15454.
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
Step 1 Click the Provisioning > Timing tabs.
Step 2 If Sync Messaging is checked, uncheck the box.
Step 3 If Sync Messaging is unchecked, check the box.
Step 4 Click Apply.
1.3.112 SWTOPRI
• Not Alarmed (NA) (Condition)
The Switch to Primary occurs when the ONS 15454 switches to the primary timing source (reference 1).
The ONS 15454 uses three ranked timing references. The timing references are typically two BITS-level
or line-level sources and an internal reference.