In WDM OTN scenario, we have multiple layers to carry the traffic from end to end.
These layers represent the overhead used for control, manage, monitor & maintain the payload.
2 types of layers used in WDM OTN as below :
- Optical layer
- Electrical layer
For Optical part, we have 3 layers :
- OCH : optical channel unit
- OMS : optical multiplex section
- OTS : optical transport section
For Electrical part we have 3 layers :
- OPU : optical payload unit
- ODU : optical data unit
- OTU : optical Transport unit
For Optical layer its called non associated overhead, its L0 (layer 0).
For Electrical layer its located inside the OTN frame and it’s layer 1.
We have what is called OSC (Optical Supervisory Channel)
It contain the optical non associated OCH , OMS and OTS overhead on 1510 nm and send them over the same fiber cable.
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