I can't find 10Gb SFP+ transceivers supporting cable length over 300mt (we need 400/500mt) is there a standard/physical limit on this, or such transceivers, with extended length support, do exist? We're using a OM4 cable...

  • You can use an "LR" SM optic with MM cable to get a bit more range. Consult the datasheet for your specific optics. – Ricky Jun 3 '20 at 14:56
  • Hello @RickyBeam, where do i get the datasheet? – Riccardo Jun 3 '20 at 15:08
  • Is this suitable? amazon.com/SFP-10G-LR-Ubiquiti-UF-SM-10G-10Gbase-LR-Transceiver/… any drawback (latency or dissipation issues) – Riccardo Jun 3 '20 at 15:12
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    @RickyBeam Beware: 10GBASE-LR is not specified for MMF, so unless a vendor specifically advertises their transceiver for MMF it may likely not work at all. – Zac67 Jun 3 '20 at 17:52
  • That''s why I said check the specs. A "mode conditioning cable" may be required, but almost any SM laser can be fired into a MM fiber -- how far it will go depends on many things. There are LRM optics specifically designed for this -- no MCC needed. Of course, your SR optics might also work to 400-500m despite only being certified to 300m. – Ricky Jun 4 '20 at 0:00

If you have not already bought and installed the cable then you should install single mode fiber instead and use LR transcievers. This is the officially supported way to do links of that distance at 10G (and beyond).

If you already have the cable installed then you may as well give a pair of LR transceivers a go. AIUI while primerally designed for singlemode they will in practice often work better than SR on long multimode runs. https://www.flexoptix.net/en/blog/2011/09/getting-a-10g-stable-ethernet-link-even-when-using-old-multimode-fiber-om2-om1/ claims they were able to get a link that passed bit error rate tests down 640M of old fiber, so 500m of modern multimode fiber sounds like it would have a pretty good shot of working.

  • Will go for the single mode cable. Is there any suggestion on this? I was told we should go for a 9/125 APC cable – Riccardo Jun 3 '20 at 16:18
  • AIUI APC is a specialist connector variant used in applications where back-reflections are unusually problematic. Regular server-room stuff tends to use plain "PC" connectors (PC and APC are NOT compatible) – Peter Green Jun 3 '20 at 16:35
  • (though you can use adapter patchcords if your infrastructure uses APC and your transcievers use PC) – Peter Green Jun 3 '20 at 16:38
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    APC is only really useful for (split) PON connections, where the angle stops unterminated ends from reflecting back energy. For P2P links, SPC/UPC are totally fine. – Zac67 Jun 3 '20 at 16:59
  • Thanks everyone, yes it's just a connection between two buildings in the campus – Riccardo Jun 3 '20 at 18:50

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