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    Locating Bit Error Rate Alarms

    Problem

    Bit error rate (BER) alarms are declared when the number of BIP-B2 errors hits a certain threshold. Depending on the threshold, there are two types of BER alarms. In both cases the interface is taken down.

    • Bit error rate-signal degrade (BERR-SD) is declared when a bit error rate of 10^-6 is reached.
    • Bit error rate-signal failure (BERR-SF) is declared when a bit error rate of 10^-3 is reached.

    Solution

    To display SONET alarms and errors, use the following Junos OS CLI operational mode command:

    user@host> show interfaces so-fpc/pic/port extensive

    Sample Output

    The following sample output displays a BERR-SD error:

    user@router2> show interfaces so-1/1/1 extensive
    [... Output truncated...]
      Active alarms  : BERR-SD
      Active defects : BERR-SD
      SONET PHY:            Seconds        Count  State
        PLL Lock                  0            0  OK
        PHY Light                 0            0  OK
      SONET section:
        BIP-B1                   22          101
        SEF                       0            0  OK
        LOS                       0            0  OK
        LOF                       0            0  OK
        ES-S                     22
        SES-S                     0
        SEFS-S                    0
      SONET line:
        BIP-B2                   22          103
        REI-L                     0            0
        RDI-L                     0            0  OK
        AIS-L                     0            0  OK
        BERR-SF                   0            0  OK
        BERR-SD                  11           53  Defect Active
        ES-L                     22
        SES-L                     4
        UAS-L                     2
        ES-LFE                    0
        SES-LFE                   0
        UAS-LFE                   0
      SONET path:
        BIP-B3                   22          166
        REI-P                     0            0
        LOP-P                     0            0  OK
        AIS-P                     0            0  OK
        RDI-P                     0            0  OK
        UNEQ-P                    0            0  OK
        PLM-P                     0            0  OK
        ES-P                     22
        SES-P                     3
        UAS-P                     1
        ES-PFE                    0
        SES-PFE                   0
        UAS-PFE                   0
    

    Meaning

    Bit error rates can be caused by any of the following situations:

    • Degrading optical fiber
    • Optical transmitter or receiver problems
    • Dirty fiber-optic connector
    • Clocking issues
    • Too much attenuation in the optical signal
    • BIP-B1 and BIP-B3 are not used in the BER alarm calculations

    Published: 2013-07-31