[Solved] BiDi fiber question

Discussion in 'Networking' started by saivert, Sep 7, 2016.

  1. saivert

    saivert Member

    Nov 2, 2015
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    I want to route a fiber from basement up two floors with minimal footprint. The cable will be visible as it will be fastened up the wall (not inside the wall) in some places. I also don't want to drill too large holes to fit two LC connectors through.
    So I decided to go with a BiDi (10GBASE-BX) solution. Here is the fs.com shopping cart for reference:

    This should do it? That and two ConnectX-2 NICs and I'm set?
    This should be much easier to route up to 2nd floor than multimode duplex cable.
    It says 20km modules in screenshot but I changed it to 10km modules. Do I still need an attenuator for short cable runs?

    EDIT: I ended up getting armored multimode LC-LC and just sucking it up and drilling a large hole. Bend radius was also a non-issue (I bend it almost as much as I did the existing Cat5e).
    Last edited: Nov 10, 2016
    Jerry Renwick likes this.
  2. tullnd

    tullnd Member

    Apr 19, 2016
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    Having literally just purchased from fs.com, both armored multimode OM4 and armored single mode cable...I can tell you there's not much difference in width between the two. Yes, the multi-mode is a bit bigger due to having two cables, but the way it's wrapped up, it's barely any bigger than the multi-mode.

    The only reason I ran both is I intend on using two sets of OM4 today for a lag. I figured for the extra cost of about $30 per run, to go ahead and put in single mode cable x2 as well, since I'm tearing open some drywall to run it hidden, and only do it once(future proofing way beyond my needs).

    So if you wanted to save a lot of money on those SFP's, you could just get multi-mode instead and the cable will be just barely larger in diameter overall.
    Jerry Renwick likes this.
  3. bds1904

    bds1904 Active Member

    Aug 30, 2013
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    Will what your proposing work? Yes, it'll work fine. It is the easiest route for sure.

    Is it what I would do? Nope.

    Most LC duplex connectors can be taken apart to separate them when feeding them through a little hole. Separate the connectors, push one through then push the other through and put them back together. You can fit the entire thing through a 3/8" hole just fine if you do it that way.

    The only thing you need to watch out for is those "round" patch cords. If you use them you need to make sure that there is enough "slack" between where the cable turns from 1 round cable to the two ends. If there isn't then you won't be able to push it through.

    If you don't feel like messing with it, just run the BiDi SM fiber and be done with it.
    Jon Massey likes this.
  4. Pete L.

    Pete L. Member

    Nov 8, 2015
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    A little tip about ordering from FS.com, Contact them before placing the order and you can probably save quite a bit on the shipping cost. Also worth mentioning they are starting to stock a lot of items in other warehouses in various locations which will make shipping even cheaper / quicker.
    Jerry Renwick likes this.
  5. pc_doom

    pc_doom Member

    Nov 2, 2016
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    My experience is a little the same as yours. I have consulted the salesman about related questions. Their tech support is really great and give me many helpful suggestions. You can also have a try.
  6. Jerry Renwick

    Jerry Renwick Active Member

    Aug 7, 2014
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    Generally, multimode systems do not need attenuators as the multimode sources, VCSELs, rarely have enough power output to saturate receivers. Instead, single-mode systems, especially short links, often have too much power and need attenuators. Therefore, most the fiber optic attenuators are single-mode
    OpticalTransceiver likes this.
  7. OpticalTransceiver

    OpticalTransceiver New Member

    Nov 9, 2016
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    I cant agree more with Jerry. These extremely short range I recommend you to use 10G SFP+ AOC or 10G SFP+ SR 300m with OM3/OM4 fiber. The Bidi you choosing according to the MSA
    Average Optical Power Pavg -8.2 to - 0.5 dBm
    Overload OL 0.5 dBm
    Receive Sensitivity Psens 14.4 dBm

    In some extreme condition it may saturate the receivers, you need to add a attenuator to make sure it works. Since Bidi using 1270/1330. Most attenuators cover this.

    10G SFP+ SR 850nm 300m Transceiver Commercial Temperature probably be more cost efficient for you application. But you may need to ask before you purchase if the transceivers need to be compatible with any switches.

    10G SFP+ AOC 850nm 15m Transceiver Commercial Temperature can save you from order fiber.
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