Diagnostics
The Diag page puts your ONUs side by side with their status, the light level in both directions, the distance and the time their status last changed. With these columns together, a bad drop cable, a splitter fault or an area power cut is easy to see. Click Diag in the side menu to open it.
The page shows the data from the last OLT read. The panel reads each OLT every 5 minutes. Opening the page, or pressing Refresh on it, reloads the list with your filters. It does not log in to the OLT.
The columns
| Column | What it shows |
|---|---|
| Status | An icon: a globe for Online, a plug for Power fail, a broken link for LOS, a globe in another colour for Offline (no known cause) and a ban sign for Disabled. Hold the mouse over the icon to read the name. A star marks a VIP ONU. |
| Signal icon | Coloured bars: good, warning or critical. |
| Rx ONU | The light the ONU receives from the OLT, in dBm, with a small bar. Click the heading to sort by signal. |
| Rx OLT | The light the OLT receives from this ONU, in dBm. |
| Distance | The fibre distance from the OLT to the ONU, in metres, as the OLT measured it. |
| Name and SN / MAC | The ONU name and serial number. Click either to open the ONU. |
| Zone and Splitter | The labels you gave the ONU. |
| ONU | The OLT and the position of the ONU on it. |
| Changed | The last time the ONU went offline or came back. |
The signal colours follow the same limits as the rest of the panel. Below -27 dBm, or above -8 dBm, is critical. From -25 down to -27 dBm is a warning. An offline ONU has no light to measure, so its signal columns show a dash. More about the values is in the optical signal guide.
The list is sorted by Changed, newest first. So the ONUs that just went down, or just came back, are at the top. The list shows up to 2000 ONUs. Use the filters to narrow it.
The filters
- Search: serial number, name or address.
- OLT, Board and Port: choose all three to look at one PON port.
- Zone, Splitter, ONU type, Sector and VIP.
- Status icons: click Online, Power fail, LOS, Offline or Disabled to keep only that status. Click the same icon again to remove the filter.
- Signal icons: Good signal, Warning or Critical.
- Status changed: two dates. Only ONUs whose status changed between these dates are shown.
Click Export to download the list you see as a CSV file.
Power cut or fibre problem?
When an ONU goes offline, the OLT records the reason. The panel turns it into one of three statuses:
| Status | What happened | Usual cause |
|---|---|---|
| Power fail | The ONU told the OLT that it was losing power, just before it went off (dying gasp). | A power cut, or the customer unplugged the ONU. The fibre is normally fine. |
| LOS | The light to the ONU was lost. | A cut, bent or unplugged fibre. |
| Offline | The ONU is offline and the OLT gave no known cause. | Not clear. Check the ONU on site. |
To check a group of customers who report no service:
- Open Diag and choose the OLT, Board and Port of the PON port. If you set splitters on your ONUs, you can choose the Splitter too.
- Look at the Status column and at the Changed column. ONUs that went down in the same event have almost the same time.
- Compare what you see with the table below.
| What you see | What it usually means |
|---|---|
| Several ONUs with Power fail and the same Changed time, other ONUs on the port still online | A power cut in one street or building. No fibre work is needed. The ONUs come back when the power returns. |
| One ONU with Power fail | The customer switched the ONU off, or its power supply failed. |
| Every ONU on the port offline, with LOS | A cut in the feeder fibre between the OLT and the first splitter. The panel also opens a "PON outage" event. |
| Several ONUs with LOS on the same splitter, the rest of the port online | A problem at that splitter or on the fibre that feeds it. |
| One ONU with LOS | The drop cable or the connector at the customer. |
| ONUs online but with a warning or critical signal | A dirty connector, a bent fibre or too much splitter loss. These customers may drop soon. |
The status comes from the down cause the OLT recorded for each ONU. Look at the pattern on the whole port, not at one ONU.
Finding weak signals before customers call
- Click the Critical signal icon, or Warning.
- Click the Rx ONU heading to sort by signal.
- Compare Rx ONU and Rx OLT, and compare the ONU with its neighbours on the same splitter. If the neighbours are good and one ONU is weak, the problem is on the drop of that ONU. If the whole splitter is weak, the problem is before the splitter.
- Look at Distance. An ONU that is far from the OLT has less light than a near one.
Related tools
- The Overview lists PON ports with two or more power fails, and ports with LOS, under "PON & signal watch".
- The "ONU status changes" report in Graphs and reports shows the history of every status change with its cause.
- The page of one ONU reads that ONU live. See ONU details.
- To ask the OLT a question directly, use the CLI tab of the OLT, with ready checks such as "Optical levels on a PON port". See OLT tools.
- Alarms and events explains the PON outage and PON signal alarms.
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