The OTN signal has a fixed pad period, the same frame period as the SDH signal.
The clock unit can only access the external clock source as the timing signal source of the system through the external clock interface. In addition; It can also output a processed clock and provide a clock source for other devices that need timing.
The index is used to folio and delineate the starting position of VC-n in the corresponding AU or TU frame so that the receiving end can correctly remove the corresponding VC from the STM-N The VC and C packages are then separated into separate low-rate signals, such as PDH That is; Low-rate branch signals can be discarded directly from the STM-N signal
The following is the frame structure of the STM-16?