PON tracer
The PON tracer follows the fiber from an OLT PON port, through every cable, splitter and splice, all the way down to a single ONU — and compares the optical power it expects at each stage with the readings on your map. You reach it on the Fiber Connectivity tab of any ONU's page. It is a powerful way to pinpoint where signal is being lost.
Opening the tracer
Open an ONU from the ONU page or from Live Topology, then select the Fiber Connectivity tab. The NMS traces the path (Tracing the fiber path from the OLT PON port…) and draws it left-to-right. The tab is only available when the ONU is placed on the Network Map.
Reading the traced path
The path is shown as a chain of nodes and links from the PON port to the ONU:
- OLT PON port: the starting node, showing the OLT name, the PON port label, its up/down status and the port TX power.
- Fiber links: each cable hop shows the fiber name, its core count and which core is used, the length in km, the distance loss in dB, and the expected (and, where recorded, measured) power.
- Splitters: shown as 1:n Splitter with the insertion loss and the expected power out.
- Splices: shown as a small Splice node.
- ONU: the end node, showing measured RX, the expected RX and the difference (Δ) between them.
The footer explains the maths: Expected power = port TX − splice/splitter loss − fiber distance (0.35 dB/km), and Measured = operator-entered core readings from the map. A Refresh button re-runs the trace.
Fault warnings
The tracer flags two kinds of problem at the top of the tab:
- Map information is incorrect: the map traces the ONU to one PON port, but the ONU is actually connected to another. The banner names both ports and links to the map so you can correct the fiber layout.
- Potential fiber issue: the measured ONU RX differs from the expected RX by more than the allowed margin. The banner shows the delta and the threshold and suggests checking for fiber bends or pressure, a bad splice, or a failing splitter.
If no fiber has been drawn to the ONU, the tracer says the route information is missing and asks you to draw the fiber links on the map to complete the path.
Tuning the power margin
The margin that decides when a Potential fiber issue is raised is the Optical margin alert threshold (default ±3 dB). You can change it under NMS settings → Alarm & Monitoring Thresholds.