User manual

DEFINITY Enterprise Communications Server Release 6
Maintenance for R6vs/si
555-230-127
Issue 1
August 1997
Maintenance Object Repair Procedures
Page 10-1217SYNC (Synchronization)
10
Figure 10-89. Synchronization Timing Loop
A correctly designed network has no loops and each piece of equipment in the
network is supplied by a clock of equal or lower stratum (that is, the inputs to a
Stratum 3 clock should NEVER be from a Stratum 4 device). It is strongly
recommended that the network administrator be consulted before
administering any synchronization changes.
The yellow LEDs of the TN768 and 780 Tone-Clock circuit packs flash in a
specific pattern to indicate the status of the circuit pack. These flashing LED
patterns are used to indicate if a Tone-Clock circuit pack is deriving timing from
an external source or whether the Tone-Clock circuit pack is providing the timing
signal for the port network. The yellow LED patterns for the TN768 and 780
Tone-Clock circuit packs are as follows:
1. Yellow LED is on 2.7 seconds and off 0.3 seconds—This light pattern
indicates that an external timing source is being used as a
synchronization reference and the circuit pack is in Active mode.
2. Yellow LED is on 0.3 seconds and off 2.7 seconds—This light pattern
indicates that the local oscillator on the Tone-Clock circuit pack is being
used as a synchronization reference and the circuit pack is in Active
mode.
3. Yellow LED stays on—This light pattern indicates that the circuit pack has
been reset but no translation has been downloaded. This pattern indicates
the circuit pack is providing clocks and is in Active mode.
4. Yellow LED off is an indication that the Tone-Clock circuit pack is in
Standby mode (neither generating tones nor supplying clocks).
SYNCHRONIZATION REFERENCE
(PRIMARY OR SECONDARY)
CORRECT TIMING
DISTRIBUTION
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TIMING LOOP
NOTE:
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