administrative unit (SDH) (AU)

Administration Unit(AU) is a term from the Synchronous DigitalHierarchy(SDH).

Administration Units( TU), which are located directly below the hierarchy of the STM-1 framework, can be grouped according to certain criteria, the so-called Tributary Unit Group (TUG). These form the Administrative Units (AU).

The Administration Units act like an adapter between the higher orderpath layers and the multiplexer section layers. The payload of such an Administrative Unit contains the Virtual Containers( VC) of the higher order, and the AU pointer shows the relative offset between the start position of the AU payload and the frame for the Multiplexer Section Layer.