I have two fiber cables in my patch panel — a single-mode simplex SC from my ISP, and a multi-mode duplex LC for 10 GbE network to my desktop computer.


When Altibox installs fiber, they usually install a wall-mounted coupler where they terminate the fiber coming from the outside junction box.

Altibox wall-mounted coupler

From this box they use a short “pig-tail” SC-SC patch to the router/home central unit.

Fiber patch SC-SC, from Altibox

Since I was planning to install a patch-panel, I didn’t want this wall-mounted coupler. So instead I asked if they could leave the fiber hanging, with a service loop. And they did 😃

Fiber service loop outside

I initially connected the fiber from outside directly to my Altibox router.

ISP fiber from outside, with service loop, connected to Altibox router

Through the patch-panel

Now — to terminate the fiber in the patch-panel I needed two things, a keystone SC-SC jack and a longer single-mode SC-SC patch fiber. Both simplex.

Fiber connector

Getting the right SC connector is important, the two most common types are SC/UPC and SC/APC.

Ultra Physical Contact
Extended polishing compared to PC connector
Loss is -50dB or higher
Blue connector color
Angled Physical Contact
Polished at an 8° angle
Loss is -60dB or higher
Green connector color

These two connector types do not fit together, that may actually damage the fiber. Seeing as the patch fiber Altibox provided had blue connectors; it uses the SC/UPC connector.

Fiber cable

Furthermore; there are two kinds of fiber cables: OS1 and OS2.

Indoor application
Tight buffer construction
1.0db/km attenuation
10 km max. distance
Outdoor application
Loose tube construction
0.4db/km attenuation
200 km max. distance

I’ve read that OS1 and OS2 fiber can not be connected together, as this may lead to poor signal performance. I figured it was most likely that the they used OS2, since it had longer maximum distance and was rated for outdoor application.

I am quite confused by the OS1/OS2 fiber types, some patch cables I looked at didn’t specify the type.

While the one I bought said OS1/OS2 in the title, and OS2 in the specifications. I suspect this means that it’s an OS2 fiber, that is OS1 compatible.

I have no way of measuring if I have “poor signal performance”, the patch fiber I got does work — I know that much.

The most common standard for single mode fiber is 9/125:

  • 9 µm diameter of the core
  • 125 µm diameter of the outside of the cladding

Wiring it up

I ordered a 1 meter long fiber patch cable with the following specifications:

  • SC to SC (UPC)
  • Single mode 9/125
  • OS2
  • Simplex
  • Outer diameter 2.0mm
  • LSZH (low smoke zero halogen)

And connected it between the keystone SC-SC jack and the SFP module in the Altibox router.

Backside of patch panel, with keystock jacks
Front of patch panel, and fiber home unit
Fiber patch connected to SFP in Altibox router

Success! 😄

I’m already planning to get a compatible SFP module for my Edgerouter 4, and skipping the Altibox router all together. But I’ll leave that for another day.


I also have a keystone LC-LC jack and a 7 meter multi-mode fiber going to my desktop computer, for 10 GbE networking, it has the following specifications:

  • LC to LC
  • Multi mode 50/125
  • OM4
  • Duplex
  • Outer diameter 2.0mm
  • LSZH (low smoke zero halogen)
Short fiber patch LC-LC
Copper and fiber cables going from patch panel across doorway

Last commit 2024-04-05, with message: Tag cleanup.