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General Chat Thread, Determing Speed of Fibre in General; What equipment/device will I require if I wanted to test the speed of a fibre cable? Also, is there a ...
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    Determing Speed of Fibre

    What equipment/device will I require if I wanted to test the speed of a fibre cable?

    Also, is there a way of finding out how many cores the fibre cable has and how many have been terminated (if that's the correct term) connected to patch panel))?

    I've never done this before so don't tell me off!

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    MK-2's Avatar
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    I believe if you put a tiny ball bearing at one end of the cable, then blow hard and time how long it takes to reach the other end you can determine the speed.
    Anything under 25s means you have a gig cable, between 25 and 20s its likely to be a damaged gig cable. anything over 1 min, chances are you swallowed the ball bearing.

    Hope this helps




    Sorry, I have no idea either

  3. Thanks to MK-2 from:

    SimpleSi (22nd March 2011)

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    The fibre 'cable' itself wont have any speed - its just a physical piece of glass/plastic

    The speed is solely determined by whatever optics you connect to each end of it. The same piece of fibre would be equally as capable of carrying 2Mbps as it would multiple 10-Gigabit wavelengths. The best way to determine that is to pull out the optic and see what the sticker says on it (or login to whatever piece of equipment its connected to and ask it)

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    36Degrees's Avatar
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    If you carefully remove the front of the fibre panel you should see where the cable itself has been passed through a gland at the back. This should have then been stripped to expose the individual cores and you will be able to see how many have been connected and if all of the available cores have been connected.

    Hopefully there will also be some details on the outer sheathing to tell you the exact specification of the cable. The details on here will determine what type of cable but in most cases I would expect it to be multi-mode fibre* as this is designed to carry multiple data streams and is therefore more likely to be used within a building (unlike single mode which carries one data stream but over a longer distance). As to the speed, this is determined by the equipment at each end.

    * Should have said, this is normally indicated by 50/125 or 62.5/125, the first number indicating the diameter of the fibre's optical core in microns (thousandth of a millimetre).
    Last edited by 36Degrees; 22nd March 2011 at 04:24 PM.

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    @chuckster
    There are 3 general types of multimode fibre used in data networks OM1, OM2 & OM3
    Each version has specific characteristics.
    To test the capability of a fibre run you need Time Domain Reflectometry TDR capable test equipment.

    By far the most commonly used fibre over the last 10 years has been 50/125 OM2
    If you have 62.5/125 there is a chance it could be older OM1

    OM1 was mostly installed in the 10/100 hay day whilst OM2 was the conduit of choice in the gigabit boom.

    OM3 is rated for 10Gbe and should be the choice for all new installations.

    Yes, you probably could push 10Gbe over an OM1 link however the losses incurred especially at the joints can be horrific and only 6db across an entire length is enough to stop a transceiver from working.
    Simple testing involves using an led light source to identify the correct core.
    Then we loop the far end with a known patch cord.
    We then send a known fixed value light source down one optic through the loop and back to the tester.
    This allows us to determine the losses from end to end.

    The TDR can identify the characteristics of the cable and determine the max speed it can carry.

    The bottom line is, without the correct test equipment you will only ever be guessing the capabilities of your fibre.

    Somewhere here I uploaded the HP Network Technichians handbook.. Check back later I'll attach it to the thread.
    Last edited by m25man; 23rd March 2011 at 12:34 AM.

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    Here it is...

    I knew it was here somewhere....
    Attached Thumbnails Attached Thumbnails Determing Speed of Fibre-hp_fiber_optic_technical_training.pdf  

  8. Thanks to m25man from:

    SteveT (23rd March 2011)

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