DEFINITY Enterprise Communications Server Release 7
Maintenance for R7r
555-230-126
Issue 4
June 1999
Maintenance Object Repair Procedures
9-1564SYNC (Synchronization)
9
coming from the PPN to the EPN over the standby fiber link). If another loss of
signal occurred after the Tone-clock circuit pack switched to receive timing from
the standby EI, the Tone-clock circuit pack will run on its local oscillator. The
yellow LED on the Tone-clock circuit pack flashes at the 2.7 seconds on and .3
seconds off rate (mostly on) if timing is received from an external source (an EI in
this example). Otherwise, if the Tone-clock circuit pack is running on its local
oscillator, the yellow LED flashes at the .3 seconds on and 2.7 seconds off rate
(mostly off).
The TN722 DS1 Interface circuit pack does not provide a synchronization
reference as reliable as the TN767 or TN464C circuit packs. Therefore, it is
recommended that the TN767 or TN464C circuit packs are used as primary or
secondary sources instead of the TN722 type DS1 circuit packs.
Stratum 3 Synchronization
Figure 9-92 illustrates one possible configuration of Stratum 3 synchronization.
Figure 9-92. Typical Duplicated Direct-Connect 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
DS-1
INTF
Clock
STRATUM 3
External
TONE/
TN780
CLOCK
and
standby
fiber
link
standby
fiber
link
active fiber link
timing info
active fiber link
and
timing info
PPN
* The EPN to EPN fiber link does not carry timing
standby
active
fiber link
fiber link
EPNEPN
DS1 References
DS-1
INTF
DS-1
INTF
