Specifications

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Cisco ONS 15454 Troubleshooting and Maintenance Guide
November 2001
Chapter 2 General Troubleshooting
2.4.7 Holdover Synchronization Alarm
The clock is running at the frequency of the last known good reference input. This alarm is raised when
the last reference input fails. See the “HLDOVERSYNC” section on page 1-43 for a detailed description
of this alarm.
Note The ONS 15454 supports holdover timing per Telcordia standard GR-4436 when provisioned for
external (BITS) timing.
2.4.8 Free-Running Synchronization Mode
The clock is using the internal oscillator as its only frequency reference. This occurs when no reliable,
prior timing reference is available. See the “FRNGSYNC” section on page 1-42 for a detailed
description of this alarm.
2.4.9 Daisy-Chained BITS Not Functioning
Daisy chaining BITS causes additional wander buildup in the network and is therefore not supported.
Instead, use a timing signal generator to create multiple copies of the BITS clock and separately link
them to each ONS 15454.
2.5 Fiber and Cabling
This section explains problems typically caused by cabling connectivity errors. It also includes
instructions for creating Cat-5 cable and lists the optical fiber connectivity levels.
2.5.1 Bit Errors Appear for a Line Card
Bit errors on line (traffic) cards usually originate from cabling problems or low optical-line levels. The
errors can be caused by synchronization problems, especially if PJ (pointer justification) errors are
reported. Moving cards into different error-free slots will isolate the cause. Use a test set whenever
possible because the cause of the errors could be external cabling, fiber, or external equipment
connecting to the ONS 15454. Troubleshoot cabling problems using the “Network Tests” section on
page 2-3. Troubleshoot low optical levels using the “Faulty Fiber-Optic Connections” section on
page 2-29.
2.5.2 Faulty Fiber-Optic Connections
Faulty fiber-optic connections can be the source of SONET alarms and signal errors.