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Guidance needed of Fiber cabling from core switch to edge switch

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  • 1.  Guidance needed of Fiber cabling from core switch to edge switch

    Posted 8 days ago
    Hi,
     
    Apologies for my naivety but I am hoping to get some guidance on the below.
     
    We have an Aruba 3810M we are using as our core switch.
     
    I setup an Aruba 6200F and attempting to connect it to our core switch.
     
    On both the core switch port and the edge switch port I have plugged in a SFP-10GLR-31 (10G SFP+ 1310nm 10KM).
     
    The switch comes online when I use the below 
     
    Edge Switch: 1M LC-SC OS1/OS2 9/125 Single mode Duplex Fibre Patch Cable https://www.jw.com.au/product/1m-lc-sc-os1-os2-9-125-single-mode-duplex-fibre-patch-cable
     
    The switch also comes online when I use the below 
     
    Core Switch: 1M LC-SC OS1/OS2 9/125 Single mode Duplex Fibre Patch Cable https://www.jw.com.au/product/1m-lc-sc-os1-os2-9-125-single-mode-duplex-fibre-patch-cable
     
    The problem occurs when I try and use the same cable type on both the core and edge switches.  If I use this cable 1M LC-SC OS1/OS2 9/125 Single mode Duplex Fibre Patch Cable
    https://www.jw.com.au/product/1m-lc-sc-os1-os2-9-125-single-mode-duplex-fibre-patch-cable to connect both the core switch and the edge switch I cannot get the link light to come on.
     
    I tested both the FS-SC-LC01 cables to confirm they are working.
     
    Would anyone know why the same cable type would not work?


  • 2.  RE: Guidance needed of Fiber cabling from core switch to edge switch

    Posted 6 days ago

    The issue you are having is prob due to the TX/RX being in the wrong ports.  

    My guess is that one of fiber cables you have is a cross-over and the other is a straight-through.  

    Lets say the FS-SC-LC01 is a cross-over:
    cross-over -> straight-through (building fiber) -> cross-over = straight-through 

    Lets say the FS-SC-LC01 is a straight-through:
    straight-through -> straight-through (building fiber) -> straight-through = straight-through 


    What you need is:
    cross-over (FS-SC-LC01) -> straight-through (building fiber) -> straight-through (FS-SC-LC01) = cross-over

    Your RX on both sides are connected to each over.  Need to swap the LC connectors around on one of the cables.

    If you unplug one end (fiber LC cable) and cup your hand around the end of the fiber you will see which side is the RX.  The side that you can see the light from is the RX pair.  Look in the transceiver and look for the side that has an active light - that is the RX side of the transceiver.  If the light is on the same side as the light on the transceiver, then you need to flip your connectors on the LC connector.



    Original Message


  • 3.  RE: Guidance needed of Fiber cabling from core switch to edge switch

    Posted 6 days ago

    The picture on the site is really blurry, but the Belkin cable does appear to be numbered as a cross-over between the ends.


    Original Message


  • 4.  RE: Guidance needed of Fiber cabling from core switch to edge switch
    Best Answer

    Posted 6 days ago

    Connecting two cross-over cables together creates a straight-through.  

    cross-over + cross-over = straight-through

    cross-over + straight-through (building fiber) + cross-over = straight-through

    You need to reverse the LC connectors on one of the Belkin cables either at the core or the access switch.

    You will then have:
    cross-over (Belkin) + straight-through (building fiber) + straight-through (Belkin) = cross-over between switches

    It is pretty easy to flip the connectors on fiber cables but if you are not 100% sure how to do it, there is youtube videos/guides you can search for.


    Original Message


  • 5.  RE: Guidance needed of Fiber cabling from core switch to edge switch

    Posted 2 days ago

    Thank you so much MFlowers!!! I REALLY appreciate you taking to explain this.  Your explanation and suggestion was perfect and fixed my issue.

    We swapped the LC connector today to create a straight through cable on the acccess switch.  My access switch is online and accessible now.  So happy! 


    Original Message