Avaya 1000 Series, Reference

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Architecture
Clock operation
There are two types of clock operation - tracking mode and free-run mode.
Tracking mode
In tracking mode, the DDP2 loop supplies an external clock reference to a clock controller. Two
DDP2 loops can operate in tracking mode, with one defined as the primary reference source
for clock synchronization, the other defined as the secondary reference source. The secondary
reference acts as a backup to the primary reference.
As shown in Figure 83: Clock Controller primary and secondary tracking on page 282, a
system with dual CPUs can use two clock controllers (CC-0 and CC-1). One clock controller
acts as a backup to the other. The clock controllers should be completely locked to the
reference clock.
Free run (non-tracking) mode
The clock synchronization of the can operate in free-run mode if:
• no loop is defined as the primary or secondary clock reference,
• the primary and secondary references are disabled, or
• the primary and secondary references are in local (near end) alarm
Architecture
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