Maintenance, Restoration, and Documentation of Optical Networks
Maintenance, restoration and documentation are tested through planned-maintenance tasks, fault-response sequence and the records that make future faults easier to fix.
Core rules
- Preventive maintenance: route patrol, chamber inspection, OTDR baseline at 1310/1550 nm, power-level checks, connector cleaning, spare-fibre and spare-card checks, battery and UPS checks.
- Keep a fibre allocation chart, splice schedule, joint numbering, cable colour code, route map or GIS, OTDR trace files, link loss budget and as-built drawings.
- Restoration: verify alarm and affected customers, test from the exchange with OTDR to locate the break, isolate, excavate or access the joint, replace the cable section, splice, test bidirectionally, restore service, then update records.
- Use a fault ticket with time stamps, location, root cause, action, parts used and test results. Close only after customer confirmation.
- Change control: any new splice or re-routing needs an updated splice loss record and OTDR trace.
Worked example
An OTDR from the exchange shows the trace ending at 3.200 km with no Fresnel end reflection, suggesting a break. A joint chamber is recorded at 3.100 km. The crew opens the chamber, confirms a cut cable, installs a 12-fibre joint closure, splices six live fibres, tests each at 1550 nm with loss ≤0.1 dB, restores service, and updates the splice schedule with the new event at 3.100 km plus 30 m slack.
Traps
- Restoring without a baseline trace, so you cannot prove the link is back to normal.
- Splicing single-mode to multimode fibre, or mixing 250 µm and 900 µm fibre without the right holder.
- Closing the ticket without updating as-built records.
- Leaving unused fibres unterminated or dirty in the closure.