ONU List
What Is an ONU?
An ONU (Optical Network Unit) is the fibre-optic modem or termination device installed at a customer's premises. It connects the customer's local network to the ISP's Passive Optical Network (PON) infrastructure via the OLT at the headend. Each ONU is uniquely identified by its serial number and communicates with its parent OLT over a shared fibre cable.
ONU List View
Navigate to Monitoring › ONU List to see all ONUs that ISPBills has discovered or registered. The list shows the following information for each ONU:
- Serial Number — the unique hardware identifier of the ONU, used to locate and provision the device on the OLT.
- OLT Association — the parent OLT and PON port that this ONU is connected to, giving you a clear picture of the physical network path.
- Rx Power (Signal Level) — the optical receive power in dBm measured at the ONU. A value within the acceptable range (typically −8 dBm to −27 dBm, depending on the hardware) indicates a healthy optical link. Values outside this range may point to a dirty connector, a fibre bend, or failing equipment.
- Status — whether the ONU is currently Online or Offline.
- Customer Assignment — the customer account linked to this ONU, allowing you to quickly identify which subscriber is affected if a device goes offline.
Troubleshooting with the ONU List
The ONU list is a first-stop resource when a fibre customer reports no connectivity. By filtering on the customer's name or the relevant OLT, you can immediately check whether the ONU is online and whether the Rx Power reading is within a healthy range. A low or absent Rx Power reading typically points to a physical fibre issue, while an online ONU with poor signal suggests degradation that may worsen over time.