What quota should be applied to the maintenance of optical cable lines

Maintenance of optical cable lines should follow ITU-T L.25 guidelines, emphasizing preventive and post-fault maintenance with periodic testing, surveillance, and network element control.

Preventive Maintenance

Preventive maintenance is aimed at avoiding faults before they occur and includes three main activities: periodic testing, fibre degradation testing, and network element (NE) control . Key aspects include:

• Periodic Testing: Regularly measure fibre loss, strain distribution, and water penetration to detect early signs of deterioration .
• Fibre Degradation Testing: Monitor for hydrogen absorption, tensile strain, bending, or alignment changes that can increase fibre loss .
• Network Element Control: Identify, transfer, and splice fibres as needed, using spare or multiplexed active fibres without disrupting transmission . The frequency of these activities should be scheduled based on network criticality, environmental conditions, and historical fault data, ensuring early detection of potential issues.

Post-Fault Maintenance

Post-fault maintenance addresses issues after a fault occurs and involves:

• Receiving alarms or trouble reports from customers or the transmission system.
• Conducting fibre fault testing to locate the problem.
• Performing cable repair, re-routing, or replacement as necessary . Fibre faults are typically classified as fibre failure, fibre loss increase, or connector abnormality, and corrective actions should be prioritized based on service impact .

Operational Considerations

• Documentation: Maintain updated records of network configuration, fibre color codes, and performance data to facilitate maintenance and fault resolution .
• Equipment Calibration: Optical power meters and testing instruments should be calibrated periodically to ensure accurate measurements .
• Service Level Agreements (SLA): Maintenance quotas may be defined in SLAs, specifying maximum fault repair times, penalties for delays, and operational responsibilities .

Recommended Quota Approach

While ITU-T L.25 does not prescribe exact numeric quotas, it emphasizes structured maintenance cycles:

1. Surveillance and Testing: Conduct at regular intervals (e.g., monthly or quarterly) depending on network size and criticality.
2. Preventive Actions: Use spare fibres for testing to avoid service disruption.
3. Post-Fault Response: Ensure rapid fault detection and repair, with response times defined in operational policies or SLAs . By following these guidelines, operators can maintain high service quality, minimize operational expenditures, and extend the lifespan of optical cable networks.