Synchronisation of a network element in a synchronous digital communication network

In a synchronous digital communication network (NET) all network elements (NE1-NE5; NE) must operate synchronously. In mutual synchronization is to ensure that no timing loops are formed. DOLLAR A A network element receives at its inputs message signals (STM-N1-STM-Nm) and reads the synchronization status messages contained therein (SSM1-HHMM). This transmits it to a central network management facility (TMN), which selects based on the synchronization status messages and based on stored information (DATA) on the structure and configuration of the network (NET) of the message signals as a timing reference and the network element (NE; NE1-NE6) selection notifies. The network element (NE; NE1-NE6) derives from the selected message signal a clock signal (CLK1-CLKm) and balances an internal clock generator (PLL) from the derived, selected clock signal. Since the network management facility (TMN), information on parallel connections (BUNDLE) of transmission lines has, the creation of timing loops is effectively prevented.