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Transmission Optical Channel of Low Quality Causes ATM Interface Drop Packet

Publication Date:  2012-07-27 Views:  54 Downloads:  0
Issue Description
Topology: NE40 (atm interface)----------(atm switch)----------(atm interface)NE20
Ping NE20 from NE40 and there is 10%~30% loss. It occurs sometimes.
Alarm Information
When there is loss. log on NE40 and execute display interface atm verbose to check ATM port state. It is found that LINE parameter has false indication.
<NE40>display interface atm verbose
.....
LINE:
        B2          0            0
      LREI          0            0      OK
      LRDI          0            0      OK
      LAIS          0            0      OK
    SFBERR          0            0      OK
    SDBERR          0            0      FALSE
       LES          0
      LSES          0
      LUAS        592
     LFEES          0
    LFESES          0
    LFEUAS        592
......
Handling Process
Check  optical channel quality with optical power and the attenuation of one optical channel is too great. Clean fiber interface with fiber cleaner and optical power recovers.
After the handling is finished and there is no loss.
Root Cause
SDBERR 
Signal Degrade Threshold Alarm
Signal degrade threshold alarm is defined as in fixed period, B2 fault reaches some value and exceeds designated value.
"LUAS", "LFEUAS"
The statistics is caused by SDBEER and means second statistics of alarm.
SDBERR, it prompts false. There is error on the cable.
Suggestions
It is suggested to measure optical power of optical channel during tamed frequency modulation of project installation.

END