Lucent Technologies DDM-2000 OC-3, User & Service Manual

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363-206-285
Transmission and Synchronization Interfaces
5-54 Issue 3 June 2001
OC-3 and OC-1 External/Line Timing 5
The external/line-timing configuration (shown in Figure 5-27) integrates loop
feeder and customer location networks into the digital synchronization network as
required by the SONET standard. This application is ideal for networks where only
one location has a BITS; for example, a loop feeder. The network is synchronized
to a local CO clock via DS1 references. The local office clock should be stratum 3
or better, with timing traceable to a primary reference source. The local
DDM-2000 OC-3 Multiplexer times its transmitted signals at the low- and high-
speed interfaces from the internal oscillator that is locked on the external
reference. The remote DDM-2000 FiberReach Multiplexer recovers timing from
the incoming OC-N signal and unidirectional timing path and uses this timing for
its transmitted signals.
This timing configuration is also recommended for multispan topologies. Line
timing can be extended to many DDM-2000 sites without any degradation of
timing quality. In the ring topology, synchronization messaging allows automatic
synchronization reconfiguration in the event of a fiber or equipment failure. See
363-206-305,
DDM-2000 FiberReach Multiplexer Wideband/ Narrowband TARP
Shelf User/Service Manual
, for more OC-1 timing configurations.