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High BEFFEC & AFEC value and R-LOS, R-LOF, ODUk-PM-DEG, ODUk-PM-SSF and BEFFEC-EXC alarms due to wrongly configure the line boards

Publication Date:  2012-07-25 Views:  112 Downloads:  1
Issue Description
- Involved equipment: OSN8800
- NE version:
- Involved board: tn52nd2
- Impact on system: unable to implement service in the network.
- Alarms: r-los, r-lof, oduk-pm-deg, oduk-pm-ssf, beffec-exc reported on the receive nd2 boards.
- Network Description:
in network “N” we have the below topology:

  • in this network we use ND2 as line & regeneration boards, TQX as tributary boards and BWS1600G as optical layer “OA, OM, OD”.
  • the ND2 boards in sites A and D used as line boards and have cross connection with the TQX boards to add/drop the service, like below:

  • whereas, in sites B and C ND2 boards are used as regenerator like the below scenario:

  • in U2000, from the wdm interface of the ND2, we choose “by function” then choose the board mode in OTM sites to line board, in REG site we choose electrical relay mode.

line mode default mode “ used in otm sites
electrical relay mode used in reg sites in traditional wdm
optical relay mode used in reg sites in ason

  • also don`t forget to set the right frequency and make the laser ON.

Alarm Information
  • R-Los, R-Lof, ODUk-PM-DEG, ODUk-PM-SSF and BEFFEC-EXC alarms reported on the receiver ports of the ND2 boards in all sites.
  • changing FEC values:


Handling Process
  1. after check the parameters of the ND2. on OTM site we set the FEC type to “FEC” as the configured service is STM-64, but in the REG sites we can`t set the FEC type.
  2. one of the parameters is the “enable auto-sensing” which is by default set to enable.

the auto-sensing means:
  • when it is set to enabled, the board supports fec type and line rate of the received signals in auto-sensing mode, and thus no manual setting is required.
  • when it is set to disabled, fec type and line rate of the board must be set manually and the values of the previous two parameters must be the same as that of the received signals. otherwise, the services are unavailable.
when the auto-sensing is set to enabled in the reg site, all the reg sites should work in the same fec mode and the same line rate. but due to a bug in the board this function not works normally, which cause the alarms to appear.
  1. change the auto-sensing mode to disabled, after doing that we check the configured FEC mode and found it set to AFEC for some wavelengths in the REG sites.

  1. set the fec mode in all ND2 boards of all REG sites to “FEC” and the line rate to “standard mode”. after that all the alarms cleared.

Root Cause
  1. check the input power valve and make sure it`s in the right range, alarm persist.
  2. increase the output power of fiu of the opposite site by increase the gain of the OA or decrease the attenuation of the VA before FIU, alarm persist.
  3. check the flatness of the wavelengths, alarm persists.
  4. check the type of DCMs in the network and make sure they are suitable.

-Check all precautions and Technical cases elated to this problem.
-Perform a warm reset to the board after changing the FEC mode & Board mode.
-Review all alarms and time sequence of the appearing of this alarms help to define the right cause for this problem.