Viavi T-BERD 5800 SFP port: Signal Present LED dark and RDI-L on an SDH circuit

First thing: how are you patching in, straight from the tester into the ODF or through a jumper you carry in the kit? And is the loop the transport team set actually confirmed in place, not just promised over the phone - for the AIS-P circuit that matters as much as anything the tester is doing.

You have three separate faults here that you are treating as one question, and they have three different causes. The dark Signal Present one is the easiest to pin down, so start there and tell us which strand of your jumper lands where.

Take them one at a time, because the tester's own troubleshooting list gives a different cause for each.

Signal Present LED not green: re-check the cabling before anything else. Tx and Rx reversed is by far the most common reason, and it is easy to do when you are patching into someone else's frame.

RDI-L: that is your transmit level being too high for what you are feeding. Put an attenuator on the module's Tx side, before the signal reaches the circuit, and it settles down. A short run with almost no loss in the path will do this to you every time.

Path Pointer Present dark with AIS-P raised: either that loop is not actually in place, or not reachable from where you are sitting, or the payload type is wrong - concatenated selected on a channelized circuit, or the other way round.

Pointer adjustments that keep incrementing are a clock problem rather than an optical one. Set the clock source to Recovered and they stop.

None of that is the module. Once the pattern is running with Pattern Sync green, judge the circuit on the bit/TSE error rate against your threshold over the full intended duration, not on how the screen looks in the first minute.

Tx/Rx it was at the first site. The jumper made up at that ODF was wired the opposite way round from the one I normally carry, so I was feeding my transmitter into the far-end transmitter. Swapped the strands at my end and Signal Present went green straight away.

The attenuator explains the RDI-L site as well - that one is a short run with next to no loss and I had nothing in line. Going to build a couple of pads into the kit so I stop walking into it.

Still working the AIS-P circuit with the transport team; payload type looks like the likely culprit there.

Polarity bites hardest when the bench and the field disagree.

We had a Turbo Chain of Moxa EDS switches with single-mode SFPs that came up instantly on the bench, short jumpers, no drama, then refused to light a single link LED once the installed field fibre was spliced in - and that cable had passed its acceptance test. The strands wree crossed, so every transmitter was feeding the far-end transmitter. Swapped the pair and all the links came up.

The bench hides it because a factory patch cord is straight through by construction, so polarity only becomes visible once the installed run is in the path. Two more things go into the same pass now. Mode first: a single-mode module facing multimode glass looks identical from the front panel, dark LED and nothing else to go on. Then power - read Rx against the module's budget instead of taking the continuity test as proof, because an installed run can easily be longer than a short-reach part will put up with.

Adding one thing to the polarity part, because it catches people on the switch side too. The classic tell is asymmetric counters: Rx climbing while Tx stays at zero, or the far end seeing nothing at all, means one side's transmit is landing somewhere other than the intended receiver. show interface counters usually settles it faster than getting a power meter out of the case.

On parallel optics it gets worse. MPO/MTP polarity comes in types A, B and C, and connectors that look identical are not interchangeable. Same fault class as your duplex jumper, just wearing a different hat.