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 pac k will run on its local oscillator. The
yellow LED on the Tone-clock circuit pack flashes a t the 2.7 seconds on and .3
seconds off rate (mostly on) if timing is received from an external sourc e (an EI in
this example). Otherwise, if the Tone-clock circuit p ack is running on its loc al
oscillator, the yellow LED flashes at the .3 second s on and 2.7 seconds off rate
(mostly off).
The TN722 DS1 Interface circuit pack d oes not provide a sync hronization
reference as reliable as the TN767 or TN464C circuit p acks. Therefore, it is
recommended that the TN767 or TN464C circ uit packs are used as p rimary or
secondary sources inste ad of the TN722 type DS1 circuit pac ks.
Stratum 3 Synchronization
Figur e 9-92 illustrates one possible c onfiguration 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 sig nal to a
TN780 Tone-Clock circuit pack, and the TN780 provid es timing to all circui t
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