SDH Multiplexing Structure


The Mapping Scheme is the basis of the SDH. It represents all functions needed to introduce a PDH signal into an SDH Network.


SDH transmission is based on standard functional entities, used to transport a characteristic

information through a connection between two Termination Points in the network.

The SDH entities are:

* C-n = Container of order n : this is the information structure carrying a synchronous


* VC-n = Virtual Container of order n: this is the information structure formed by C-n+ Path

Over Head (POH)

* TU-n = Tributary Unit of order n: information structure formed by VC-n + Pointer

* AU-4 = Administrative Unit of order 4: information structure which provides for adaptation

(synchronization) between the Virtual Containers (VC-n) and the multiplexing plane (=

STM-N); it is formed by VC-4 + Pointer

* POINTER = Indicator of off-set for VC-n ( it indicates the start position of VC-n inside the


*  TUG/AUG = Tributary Unit Group / Administrative Unit Group = a set of n x TU / n x AU

* TU12 is identified by (k,l,m) with: k= TUG3# (1…3); l=TUG2# (1…7); m=TU12# (1…3)

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