1000BASE-ZX GBIC Question

Discussion in 'Cisco' started by Daniel Conlon, Sep 22, 2004.

  1. I have purchased two 1000BASE-ZX GBICs for use on a run of SMF over which LX
    GBICs did not work.

    Cisco.com recommends the use of attenuators for runs less than 25 km. I have
    the attenuators and will test the link using them first. If the link does
    not work with the attenuators, is it safe to test the link without the
    attenuators? i.e. can the GBICs be damaged by too powerful a light source
    being inputted into the rx side?

    From cisco.com:

    The Cisco 1000BASE-ZX GBIC (WS-G5487) operates on ordinary single-mode fiber
    optic link spans up to 43.4 miles (70 km) long. Link spans of up to 62 miles
    (100 km) are possible using premium single-mode fiber or dispersion shifted
    single-mode fiber. The GBIC provides an optical link budget of 23 dB-the
    precise link span length will depend on multiple factors such as fiber
    quality, number of splices, and connectors.

    When shorter distances of single-mode fiber are used, it might be necessary
    to insert an in-line optical attenuator in the link to avoid overloading the
    receiver:
    A 5-dB or 10-dB inline optical attenuator should be inserted between the
    fiber-optic cable plant and the receiving port on the Cisco 1000BASE-ZX GBIC
    at each end of the link whenever the fiber-optic cable span is less than
    15.5 miles (25 km).

    Many thanks for your help in advance.

    Dan
     
    Daniel Conlon, Sep 22, 2004
    #1
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  2. Daniel Conlon

    Steinar Haug Guest

    ["Daniel Conlon"]

    | Cisco.com recommends the use of attenuators for runs less than 25 km. I have
    | the attenuators and will test the link using them first. If the link does
    | not work with the attenuators, is it safe to test the link without the
    | attenuators? i.e. can the GBICs be damaged by too powerful a light source
    | being inputted into the rx side?

    Yes, ZX GBICs can be damaged if the attenuation is too low - they can *not*
    be run back to back.

    Steinar Haug, Nethelp consulting,
     
    Steinar Haug, Sep 22, 2004
    #2
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  3. Daniel Conlon

    AnyBody43 Guest

    (Steinar Haug) wrote in message news:<>...
    > ["Daniel Conlon"]
    >
    > | Cisco.com recommends the use of attenuators for runs less than 25 km. I have
    > | the attenuators and will test the link using them first. If the link does
    > | not work with the attenuators, is it safe to test the link without the
    > | attenuators? i.e. can the GBICs be damaged by too powerful a light source
    > | being inputted into the rx side?
    >
    > Yes, ZX GBICs can be damaged if the attenuation is too low - they can *not*
    > be run back to back.
    >
    > Steinar Haug, Nethelp consulting,


    Hmmmm. Seems unlikely to me. Can you please point me to
    something convincing on the web?
     
    AnyBody43, Sep 22, 2004
    #3
  4. Daniel Conlon

    Steinar Haug Guest

    [AnyBody43]

    | > Yes, ZX GBICs can be damaged if the attenuation is too low - they can *not*
    | > be run back to back.
    |
    | Hmmmm. Seems unlikely to me. Can you please point me to
    | something convincing on the web?

    How about

    http://www.cisco.com/en/US/products...on_guide_chapter09186a00801d5800.html#1022899

    which states that the Cisco ZX GBICs have a max output power of 4.77 dBm,
    and a max input power of -3 dBm?

    Steinar Haug, Nethelp consulting,
     
    Steinar Haug, Sep 22, 2004
    #4
  5. > | > Yes, ZX GBICs can be damaged if the attenuation is too low - they can
    *not*
    > | > be run back to back.
    > |
    > | Hmmmm. Seems unlikely to me. Can you please point me to
    > | something convincing on the web?
    >
    > How about
    >
    >

    http://www.cisco.com/en/US/products/hw/switches/ps606/products_installation_
    guide_chapter09186a00801d5800.html#1022899
    >
    > which states that the Cisco ZX GBICs have a max output power of 4.77 dBm,
    > and a max input power of -3 dBm?


    But does that mean that they will actually be damaged, or just that the link
    will not work?
     
    Daniel Conlon, Sep 23, 2004
    #5
  6. Daniel Conlon

    Steinar Haug Guest

    ["Daniel Conlon"]

    | http://www.cisco.com/en/US/products/hw/switches/ps606/products_installation_
    | guide_chapter09186a00801d5800.html#1022899
    | >
    | > which states that the Cisco ZX GBICs have a max output power of 4.77 dBm,
    | > and a max input power of -3 dBm?
    |
    | But does that mean that they will actually be damaged, or just that the link
    | will not work?

    A sufficiently high optical power level will certainly damage a GBIC in
    the sense of shortening its lifetime.

    Given the cost of ZX GBICs, it's much simpler to just stay within specs
    and make sure you have sufficient attenuation.

    Steinar Haug, Nethelp consulting,
     
    Steinar Haug, Sep 23, 2004
    #6
  7. > > | > Yes, ZX GBICs can be damaged if the attenuation is too low - they
    can
    > *not*
    > > | > be run back to back.
    > > |
    > > | Hmmmm. Seems unlikely to me. Can you please point me to
    > > | something convincing on the web?
    > >
    > > How about
    > >
    > >

    >

    http://www.cisco.com/en/US/products/hw/switches/ps606/products_installation_
    > guide_chapter09186a00801d5800.html#1022899
    > >
    > > which states that the Cisco ZX GBICs have a max output power of 4.77

    dBm,
    > > and a max input power of -3 dBm?


    Since I tried LX GBICs and they did not work, and they have a maxium output
    power of -3 dBm and reciever sensitivity of -19 dBm, can I deduce from this
    that the fibre run has at least a 16 dBm loss?

    And assuming that is the case, can I also deduce that the maxium input power
    over the run with the ZX GBICs will be -11.23dBm (4.77 - 16) and therefore I
    may connect the ZX GBICs up with no risk of exceeding the maximum input
    power?
     
    Daniel Conlon, Sep 23, 2004
    #7
  8. Daniel Conlon

    Steinar Haug Guest

    ["Daniel Conlon"]

    | Since I tried LX GBICs and they did not work, and they have a maxium output
    | power of -3 dBm and reciever sensitivity of -19 dBm, can I deduce from this
    | that the fibre run has at least a 16 dBm loss?
    |
    | And assuming that is the case, can I also deduce that the maxium input power
    | over the run with the ZX GBICs will be -11.23dBm (4.77 - 16) and therefore I
    | may connect the ZX GBICs up with no risk of exceeding the maximum input
    | power?

    That sounds like a reasonable assumption if it is the attenuation
    which prevents the LX GBICs from working. You could possibly also
    have a faulty GBIC.

    To be certain I would advise measuring the loss in the fibre.

    Steinar Haug, Nethelp consulting,
     
    Steinar Haug, Sep 23, 2004
    #8
  9. On 23 Sep 2004 08:20:00 GMT, (Steinar Haug) wrote:

    >A sufficiently high optical power level will certainly damage a GBIC in
    >the sense of shortening its lifetime.
    >
    >Given the cost of ZX GBICs, it's much simpler to just stay within specs
    >and make sure you have sufficient attenuation.


    Indeed. In the world of optical, it's extremely important not to
    overload receivers.

    -Terry
     
    Terry Baranski, Sep 24, 2004
    #9
  10. Daniel Conlon

    lovemore

    Joined:
    Oct 8, 2007
    Messages:
    1
    Gbic 1000Base ZX

    I am also having problems with my two Cisco Gbic 1000Base ZX. I have connected them using using an 80Km run of fiber between them. the fiber had a break and i respliced the fiber and at that plice the loss is 0.003dBm and the total loss for the 80km is 28dBm.

    The problem here is after respicing my Gbic can nolonger see each other. what coud be the problem. If i cconnect them on a distance of 10km they can see each other.
     
    lovemore, Oct 8, 2007
    #10
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