Signal loss on a fiber port on CISCO switch

Posted on 2006-03-30
Last Modified: 2010-03-19
How much signal loss on a fiber port on a CISCO switch is required to constitute the link state as down?
Question by:jbowlin
    1 Comment
    LVL 12

    Accepted Solution

    A SONET link must see a certain number of digital bit transitions (from 1 to 0 and 0 to 1) in order to ensure proper synchronization. LOS is declared when no bit transitions are detected on the incoming signal (before descrambling) for 2.3 to 100 microseconds. The LOS defect is cleared after a 125 microsecond interval (one frame) during which no LOS defect is detected.

    Note: LOS typically occurs in back-to-back lab setups because the receiver is saturated with too much light, particularly when long-reach single mode interfaces are used. Try to attenuate the signal.

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