1

We have a 1Gbps single mode fiber run where I only directly control one end of the link, connected via media converter that has failed. The existing fiber uses a simplex SC connector I'm not equipped to re-terminate on my own. Looking up the specs for the media converter, it transmits at 1310nm and receives at 1490nm (no SFP; the optics are built in).

For some reason I've had a hard time finding a transceiver or with an exact match for the media converter (plenty like this if I needed an LC connector instead), but I do see a number of options specced for 1310nm TX/1550nm RC. Would this work? If so, is there a performance or signal penalty for the mismatch?

I know fiber itself can use either/or (it's just the medium), but again: I can't change the transceiver on the other end to match.

1
  • 2
    SC/LC converters are simple and plentiful. As you've already figured out, the wavelengths must match. The other thing to keep in mind is the end of connector -- APC vs. UPC.
    – Ricky
    Nov 20, 2023 at 6:31

2 Answers 2

2

1310/1490 nm sounds like 1000BASE-BX10 - these SFPs are quite common with a SPC/UPC simplex-LC connector. You'd need a 1000BASE-BX10-U SFP (-U faces the network center, -D faces the edge). You should verify with the ISP whether such an SFP would work, they should be able to indicate the specs you require.

You could use a media converter with an SFP port and an LC/SC adapter like you've indicated (or better, swap the patch cable for a converting one). It's also possible that a passive optical network is used, which would require a special media converter and SFP. A 1310/1550 nm bidi SFP will not work.

It's important to match green connectors for APC, or blue connectors for SPC/UPC. Mismatching the end surface will not work and may even damage the jacks.

The media converter you've linked to includes a 1000BASE-SX SFP (850 nm for multi-mode fiber) which will not work.

4
  • The SFP with the media convert is kind of just thrown in... not the one I plan to use; that's another link. But thanks for the blue/green heads up, as the connector on the fiber is green, so the blue adapter I linked is likely wrong. Nov 20, 2023 at 14:25
  • But I think you're likely right about the passive fiber. The link is built using equipment normally provided for consumer broadband, which I think tends towards passive. It's even possible it routes through the local ISP office before heading to the hospital (again: before my time, and til now it's always just worked) Nov 20, 2023 at 14:34
  • That did lead me down some fruitful new paths, though, and my own answer has changed. Nov 20, 2023 at 14:49
  • A green APC connector may be an indication of a passive optical network. Both ITU-T G.984 and IEEE EPON require special media converters (or ONTs) with TDM support. You should definitely ask your ISP about the requirements before buying anything.
    – Zac67
    Nov 20, 2023 at 15:14
0

After more of my own research, I now believe this will not work. I will need to match up exactly with the other transceiver.

Especially considering the nature of this link: we're a school, and the connection runs to the local hospital in support of a nursing program using equipment donated by the local ISP that's normally used for consumer broadband. It seems it's common for ISPs/TV services to use 1310/1490 for send/receive, and 1550 at the same time to deliver TV. This ISP does not do that, but it looks like the same equipment is used by providers who do, which tells me it's not likely to correctly see or adapt to the return signal on 1550 instead of 1490. It also tells me I should be looking for passive fiber options.

The good news is I can likely get the ISP to just donate another unit... but that could take a while. In the meantime, I can get a 3rd party consumer GPON ONT that will matching specs, and that should do the job. This was why I wasn't finding compatible SFPs: I needed to be looking for passive GPON connections.

1
  • In case it helps widen the selection of devices you can use, it is extremely easy to just add a patch cable on the end of the connection to convert from SC to LC connectors. You get an SC to SC coupler and an SC to LC pre-made patch cable and now your connection is terminated with an LC connection instead of SC. Nov 20, 2023 at 15:15

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.