I will have a new fiber optic Internet connection coming in to building A, and need to set up an access point in building B. Both are commercial buildings. The fiber Internet is currently 20 Mbps, but potentially up to 1000 Mbps.

The buildings are line of sight but there are trees, and in winter it snows up to 5-30 feet deep. Point to point wireless is in use now, but it just won't work well after storms when the trees are snow laden. I'm not on site regularly, so I have to execute in one shot.

I know I could run cat6 cable tree to tree, with lightning protection blocks, and possibly an optical isolation gadget at one end.

AT&T Dedicated Internet abandoned a fiber cable running almost the entire distance. With the right knowledge, and a fiber Ethernet bridge, that could do it. It's whatever fiber they would have used - unknown if it's single mode or multi-mode or what.

Or, I could run new fiber from tree to tree. With a learning curve on fiber types, connector types, polishing, and hanging.

I'd call in a networking company, but the location is in the boondocks. How would you get this job done? What's the barrier to entry for a first time (only time) DIY run like this? Is there a good guide to connector types and cable options,especially for fiber? I see a lot of fiber equipment, but not a lot of "sets" of cable/connector/repeaters that are all ready to play well together.

Building to Building Ethernet in snow country

  • Which is building A, which is B? Oct 25, 2018 at 6:55
  • @Ward Does that make a difference to how you'd do it?
    – kasperd
    Oct 25, 2018 at 10:17
  • The upper left is A, the lower right is B. Direction won't matter: both ends have power, dry equipment closets, etc. There's even some existing cat3 (or earlier) wiring from the 1950's for an old fire alarm between the locations.
    – Bryce
    Oct 25, 2018 at 19:20
  • 1
    If you use the AT&T fiber, keep everything outside fiber. If that means a 50 meter patch cable on one end, do that instead of trying to do the fiber to copper conversion in a box outside.
    – longneck
    Oct 25, 2018 at 19:21
  • re: the cat3, is it in conduit, or direct burial? If conduit, then just pull new fiber all the way!
    – longneck
    Oct 25, 2018 at 19:21

2 Answers 2


Cat6 for outdoor usage will cost more than a fiber of the same outdoor grade and regardless of lightning protection it will cause trouble sooner or later - we had an abundance of aerial lines of all kinds few years ago so this gave us some insight. Using indoor cable warrants a failure within a year.

You can identify the fiber type (SM or MM) by inspecting cable markings, it's all written on the cable itself; connectors can be identified by photo, they are usually SC/APC (green square), SC/UPC (blue square) or FC (black barrel). If you plan on using existing fiber, you should at the very least check for its continuity using appropriate light source.

For the self-laid fiber the main obstacle is how are you going to terminate it, as you'll need a bunch of equipment and experience to properly weld it. Of course, you can pre-weld splice boxes on the cable somewhere, but the question is how are you going to get these boxes from the street into the building when they are already attached to the cable - that is they can't get through the small neat round hole.

So if I would be you I would have tried to inspect and use existing fiber and if it won't work seek professional help.

  • I've watched the local independent ISP installers terminate their fiber ( sonic.com ). They seem to know what their doing, and use just a pair of wire strippers, and a dance to avoid scratching. Is there a good pictorial guide to connectors, fiber types and termination? Also I see lots of two fiber cables, and wonder why one would pick a two fiber setup over a single piece of glass.
    – Bryce
    Oct 25, 2018 at 19:23
  • 1
    The most problematic part is not cutting and cleaning, you need a fusion splicer and some first-hand experience with it to terminate correctly. Granted, it looks easy when you're looking at someone doing it, but remember they have done it before a few hundred times. For a complete reference guide take a look at the FOA Guide: thefoa.org/tech/ref/contents.html Number of fibers needed depends on the technology selected, there are transceivers that can support 1000Base-LX in single fiber using different wavelengths for RX and TX. Oct 25, 2018 at 19:55

AT&T fiber is single-mode for sure. Multi-mode fiber has very limited reach.

You can get very affordable media converters or SFP modules for 1000BASE-LX which is the protocol of choice here. In case there's only a single fiber you'll need to use 1000BASE-BX(10) which is just slightly more expensive.

Reterminating the abandonded fiber might cost you a few $100 though. You'll want to get SC or LC connectors on the panels.

  • Pretty sure it's just one fiber strand, so no separate TX RX fibers. I'm concerned I may need an outdoor splice just prior to Building B. It's also a bit murky if AT&T, which no longer serves building B or owns the trees, would ever decide to rip it all out through sloth or spite.
    – Bryce
    Oct 25, 2018 at 19:27
  • I don't think they'd bother.
    – Zac67
    Oct 25, 2018 at 19:53

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