G.655 fiber and GLC-LH-SM GLC-ZX-SM

Discussion in 'Cisco' started by stonewealth, Dec 4, 2005.

  1. stonewealth

    stonewealth Guest


    I have a project which uses Cisco catalyst switch 2970 for two sites,
    connected by G.655 single mode fiber. Depending on the distance, I
    will be using either GLC-LH-SM or GLC-ZX-SM SFP transceiver module for
    my switch.

    From Table 2 SFP Transceiver Module Cabling Specifications
    in the URL
    , the SMF fiber recommended for GLC-LH-SM or GLC-ZX-SM is G.652.

    However, the fiber will be G.655 instead of G.652 standard.

    My question is whether there will be any issue using G.655 fiber for

    If not, assuming that I cannot change the fiber to G.652, is there
    any solution?

    Thank you very much for any pointers and advice.

    Best regards

    stonewealth, Dec 4, 2005
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  2. stonewealth

    stephen Guest

    if you look at:

    it implies that the G.655 fibre is "better" quality - similar loss, and
    lower dispersion than base G.652.

    the description here also implies G.652 is the baseline, and the other
    variaties mentioned are improved for various applications.

    FWIW most of the issues mentioned are only a problem at higher speeds (say
    10G), with DWDM, and /or long distances, so as long as you are not trying to
    push the limits on the kit you use you should be OK.
    i think it will be OK - but you arent paying for formal professional
    opinions on Usenet........
    go to whoever you are buying the cisco gear from and get them to issue an
    opinion (preferable backed by Cisco, and in writing).
    stephen, Dec 4, 2005
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  3. stonewealth

    stonewealth Guest


    For the benefit of those who is following this thread, I just got
    reply from Cisco engineer, so I would like to share the knowledge with
    the group:

    " Cisco does not certify the use of the G.655 fiber with Gigabit
    Ethernet. It does not mean that it would not work but the distance
    could be impaired. For example, if you use G.655 fiber with the
    1000BaseLX/SX cable, its response would be like a multimode fiber
    instead of a singlemode fiber. The reason is that the G.655 standard
    specify that the cable cut-off is <1480nm and 1000BaseLX/SX cut-off
    needs to be max 1270nm.

    For the 1000BaseZX GBIC, it uses the 1550nm so would be closes to
    what you could be using. So you might probably explore using this GBIC
    instead of GLC-LH-SM for distance < 10km if you are using G.655 fiber
    instead of G.652 fiber. In this case, you need to check if any
    attenuator is needed if the cable is too short to reduce the power. "

    Best regards
    stonewealth, Dec 6, 2005
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