Hi guys!!
I would like to share with you the following case related with an Inter-NE fiber connection cutting off.
Description:
In this case, the CWDM ring network topology is as follows:
The equipments deployed on this transmission network are OptiX OSN 1800 (V100R002C00).
When the Inter-NE fiber connection (two-fiber bidirectional transmission) is cut off between any 2 nodes, for example among Site B and Site C, the Inter-NE fibers don't turn red in U2000.
The question is: Why in U2000 the fiber connection between 2 NEs doesn't turn red in case of cut?
Solution:
The scenario between Site B and Site C is shown below:
and the Intra-site fiber connections are as follows:
After cutting off the Inter-NE fiber connections, R_LOS alarm appears on the LQM2 Optical Transponder Boards in both sites, Intra-side fibers connected on the IN ports of the LQM2 boards turn red, but Inter-NE fibers remains green.
The reason for this behavior lies in the fact that the Inter-NE fibers are connected through MD8 boards. According to the OptiX OSN 1800 Hardware Description document (attached), MD8 board only reports the following alarms:
Therefore, due MD8 board doesn't report the R_LOS alarm or similar, the Inter-NE fibers don't turn red.
To verify this detail, the design of the nodes is changed by adding an OPU unit in both ends of the link between Site B and Site C.
Now the scenario between Site B and Site C is shown below:
and the Intra-site fiber connections are as follows (in both sites):
With the current situation, after cutting off the Inter-NE fiber connections, R_LOS alarm appears on the LQM2 Optical Transponder Boards in both sites, Intra-side fibers connected on the IN ports of the LQM2 boards turn red and the Inter-NE fibers also turn red because MUT_LOS alarm appears on the OPU Optical Preamplifier Boards in both sites.
Conclusion:
When optical cable is cut off, fibers in U2000 will turn red only if the boards at both ends of the link report at least one of the following alarms: R_LOS, MUT_LOS or OTS_LOS.
Cheers!!
