Avaya Definity SI, Maintenance Manual, Page: 2377 / 2968

SYNC (Synchronization)
Issue 4 May 2002 10-1591 555-233-123
Figure 10-93. 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).
Communications
system
Generic 2
Communications
system
Generic 2
Communications
system
Generic 1
Communications
system
Generic 1
Communications
system
Generic 1
Communications
system
Generic 1
Timing
loop
Correct
timing
distribution
r11n1p3 LJK 072501
Synchronization reference
(primary or secondary).