NEC Electra Elite IPK II System User Manual page 324

Document Revision 4C
In this example, the PRI in S4 was the first to synchronize with the carrier and became the PLO
synchronization source. The PRI in S4 then went down and the system began looking forward in slot
numbers to find the next PLO source. In this case, the PRI in S1 was the next source because after it
looks through the rest of the slots in the system, it starts over with S1.
In this example, there are multiple T1 circuits in the system. There can only be one T1 circuit assigned
as EXTERNAL in the system, so the T1 assigned as EXTERNAL is the PLO synchronization source.
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Figure 2-5 Digital Trunk Clocking Example 3
Figure 2-6 Digital Trunk Clocking Example 4
Electra Elite IPK II
Digital Trunk Clocking