Light levels can be checked at various accessible points in the network. Light levels are the very simple first step in testing. OTDR is a more sophisticated next level of diagnosis.

Depending on the type of fault / further diagnostics can be carried out with an OTDR into a live network using a PON-aware OTDR (uses a specific wavelength that doesn’t interfere with GPON or other operational upstream and downstream wavelengths on the network). OTDR’s can pick up “loss events” along the full path of the fibre; splices, connections, PON-aware OTDRs can also detect/map out passive elements like splitters etc. If the fibre has suffered from external damage or an anomaly that isn’t otherwise physically obvious like a macrobend, these will also be detected in an OTDR trace.

As portable OTDRs are usually very expensive, I believe there is a pilot program at Openreach to install permanent OTDRs atthe headend exchange and then a relatively simple, cheap field unit that was connected (typically at a CBT port) that could have engineers run cloud based diagnosis using a smartphone app. It is intended I believe as part of the “build assurance” of new rollouts but wasn’t itself rolled out everywhere.

https://www.exfo.com/en/corporate/news-events/press-...

https://www.exfo.com/en/products/service-assurance-p...

@Zarajaz may have details?

That is actually quite interesting. I didn't know what equipment was used but I knew fibre diagnostic equipement existed but how it worked and in a pon setting i wouldn't have had a clue. Its not something i would know in my daily work or cared for. 😁

The interesting part is that they upping the error correction with the "new" fibre network and that is good long term for the bean counters and us as users of their network

OpenReach turned up this morning and said they had done something to the splitter and to test the speed.

Back up to 800/down and 108/up.

Glad it's resolved. Hopefully it will be fine from here on in.