STM1 T1/E1 Clocking

he DS1 Clock Source options should be interpreted as follows:

• Master Clock (Default)

  • Derive clock from Upstream (OC-3 side) and pass it to the T1/E1 interfaces.

  • Master indicates that STM1 T1/E1 interfaces are Master clock to external T1/E1 equipment.

• Normal Clock (Used in Testing or back to back)

  • Derive clock from external T1/E1 interfaces and pass it to OC-3 side.

  • Normal indicates that STM1 T1/E1 interfaces are slave to external T1/E1 eqipment.

Figure 3.2.2-1 illustrates how the STM-1 Mux acts as a “pass-through” for T1 Master Clock coming from “Upstream”.

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