We just moved into a commercial building that is quite long and I have discovered that the previous owner at some point ran a fiber line from the front to back. I would love to utilize this, having a MiktoTik router at the front where the internet comes in and then another MikroTik router at the back. I’m pretty familiar with MikroTik routers but have never dealt with a fiber connection before. I’m hoping there is someone on here who could point me in the right direction.
Following is a picture of the end connectors. Looks the same from both ends. From my research, these are ST ends.
I bought a 1.25G SFP LC Transceiver and a LC to ST fiber cable and connected on both ends. I plugged in the transceiver to the SFP port on each end. But at this point, I’m stuck. I expected maybe to see some light on the router or some indication of something but don’t see anything happening. On the interfaces in WebFig, the SFP port shows no link. Is there something else I need to do to enable this? Would a fiber line typically have a power source somewhere or does the MikroTik handle all of that?
Assuming you have LC-Duplex SFPs (one fiber for Tx, another one for Rx), have you tried to swap the two fiber connectors at one of the ends? Or perhaps you know exactly which one is which and you have connected Tx of one SFP to Rx of the other one and vice versa?
And an afterthought as you are apparently a true newbie in optics - there are multiple caveats:
two parts of the connector shape: the “visible” one (on the picture, ST) and the “invisible” one - how the contact surface is polished (PC, UPC, and APC, where the first two are mutually compatible but the latter one must only be mated to another APC, otherwise there is additional attenuation)
the diameter of the optical core: there is Single Mode (SM) fiber and Multi-Mode (MM) one - again, a mismatch adds a lot of attenuation
multiple wavelengths (or “colors”) - the fiber itself doesn’t care, but the transmitter and receiver must be compatible
So what is written on the labels of the SFPs, what color are the LC-to-SC patchcords you have purchased (both the color of the LC connector housing and the color of the cable coat are important)?
And when inserting those connectors please be aware there are two keys in that connector. The first is on the silver part. The other is on the black inner housing. Line them both up correctly to the socket they are going in. The black part is easy enough to force incorrectly in to a plastic socket.
What I purchased for the SFP connector is described as: “1.25G 850nm Multimode SFP LC Transceiver Fiber Module 550 Meters 1000Base-SX LC MMF for Cisco GLC-SX-MMD/SX-MM/SFP-GE-S,Fortinet,Ubiquiti UniFi UF-MM-1G,Mikrotik S-85DLC05D Meraki MA-SFP-1GB-SX”
And then “1ft Fiber Optic Adapter Cable LC (Male) to ST (Female) Singlemode 9/125 Duplex”
I don’t see LC-Duplex in the description so do I have the wrong adapter?
Below is a picture of the connection. The orange cable is the fiber internal fiber line. The yellow is the Optic Adapter Cable.
Since the existing cables are orange (but my color perception is not ideal so I may be wrong), your choice of SFP was incidentally correct (orange coating normally means multimode), whereas your choice of the adaptor patchcords was incidentally wrong (yellow coating normally means single mode). The SFPs are clearly LC Duplex simply by shape - if they were not, they would only have a single hole for the optical connector.
So this way, you’ve got two places where a narrow beam from a 9µm tunnel hits a wide tunnel of 50µm, but even worse, two more places where the wide beam hits a narrow tunnel, in each direction. These non-matching connections add so much attenuation that the receiver cannot work with the signal that remains.
Possibly simpler is to highlight the modes to better understand the basic incompatibilty:
What I purchased for the SFP connector is described as: “1.25G 850nm > Multi> mode > SFP LC Transceiver Fiber Module 550 Meters 1000Base-SX LC MMF for Cisco GLC-SX-MMD/SX-MM/SFP-GE-S,Fortinet,Ubiquiti UniFi UF-MM-1G,Mikrotik S-85DLC05D Meraki MA-SFP-1GB-SX”
And then “1ft Fiber Optic Adapter Cable LC (Male) to ST (Female) > Single> mode > 9/125 Duplex”
I returned the yellow LC-to-SC patch cord and got the orange multi-mode one and got the connection working. Really appreciate everyone’s help on this, thanks!
