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One NS3 board has OTUk-LOF alarm duo to the port of demultiplexing board fault

Publication Date:  2012-07-25 Views:  38 Downloads:  0
Issue Description
 project background: Huawei NG WDM Series Product Test for Vodacom in South Africa.
product: Optix OSN 8800&6800 version:V100R006C01SPC200B011
networking modes:four nodes named A,B,C,D.which establish a  mesh network. and Node A:8800T32+6800,Node B:8800T16+6800, Node C:8800T32+6800, Node D:8800T16+6800
we use three NS3 and two ND2 boards on Node A, and use one NS3 board both on Node B and D, and use two NS3 and two ND2 boards on Node C. There are three trials between Node A and C: A-C, A-B-C, A-D-C. There is still one link both between A-D and A-B.
fault symptom:After creat all the OCH trial between A and C and adjust the optical power in both Nodes, all the OTU boards have no alarm except one NS3 board on Node C has OTU3-LOF alarm
Alarm Information
Alarm: OTU3-LOF
Handling Process
pcosess 1: check the opposite Node A 's  client  side input and DWDM side output optical power, the result is nomal.
process 2: check the opposite Node A OBU's output optix power and  Node C input power is right or not, the result is ok.
process 3: LOOP this two NS3 boards between Node A and Node C, the OTUk-LOF alarm disppeared. so maybe the cable betweeen demultiplexing board and this alarm NS3 is something wrong.
process 4: change the cable between demultiplexing board and this alarm NS3, the OTU3-LOF stil exist.
process 5: Maybe the demultiplexing port that this NS3 connected has broken, so we use a new  demultiplexing port to connect with NS3, and the OTU3-LOF alarm disppeared.
Root Cause
cause 1: the opposite Node (A) NS3 board fault or the cable between NS3 and multiplexer board maybe something wrong
cause 2: the cable  between demultiplexing board and NS3 board on Node C maybe broken.
cause 3: optical power too high or too low
cause 4: FEC mode differents on Node A and Node C
cuase 5: this Node C NS3 board fault

first , we must make sure the optix power is in the right range.
second, LOOP the board is a good method to find the problem where it is.
third, find the fault point  following  the singal flow step by step