SYNC (Synchronization)
Issue 4 May 2002
10-1589 555-233-123
Figure 10-92. Example Stratum 3 Synchronization Configuration
For Stratum 3 synchronization, an external clock provides a timing signal to a
TN780 Tone-Clock circuit pack, and the TN780 provides timing to all circuit packs
in the port network in which the TN780 resides (that is, the PPN in the previous
diagram). The PPN Expansion Interface circuit pack uses the timing generated by
the TN780 to generate a data stream which is sent across the two Expansion
Interface Links to the two EPNs to the EPN Expansion Interface circuit packs. The
EPN Expansion Interface circuit packs use the received data stream to generate a
timing signal which is used by the Tone-Clock circuit packs in the EPNs to provide
timing for all circuit packs in both EPNs. (The Tone-Clock circuit pack is not
necessarily a TN780; only the Tone-Clock circuit pack connected to the external
Stratum 3 clock must be a TN780.) The PPN, in the above mentioned scenario, is
designated the master port network and the EPNs are called slave port networks.
The master port network is defined as the port network whose Tone-Clock is
connected to the Stratum 3 clock.
TN780
TONE/CLOCK
PPN
EPN
EPN
EXTERNAL
STRATUM 3
CLOCK
DS1 REFERENCES
TIMING
INFO
EI LINK
EXPANSION INTERFACE (EI) LINK*
* EPN-TO-EPN LINKS ARE NOT USED TO CARRY TIMING
TIMING
INFO
EI LINK
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