The definition of hierarchy levels specifically refers to OpenScape 4000 in this case. However, it can also be used for other transmission networks (with necessary modifications). Division into levels is necessary so that a network can function with good enough quality in the event of errors.

The connections between systems are clock transparent. The number of repeaters is only limited by the jitter and drift values provided by the route and which must comply with the input requirements.

( --> Connections)

The route clocking source should be investigated or determined in the case of non-clock-transparent routes. For leased lines, this can be the master for both systems at the connection's endpoint. However, make sure that the connection always has an external clocking source. Avoid a return to clock-transparent operation during a failure without informing the network management centers involved, since this procedure results in a forbidden clock loop.

( --> Connections, AMO REFTA)