DEFINITY Enterprise Communications Server Release 7
Maintenance for R7r
555-230-126 Issue 4
June 1999
Maintenance Object Repair Procedures
9-247ATM-SYNC (ATM Synchronization)
9
circuit pack p rovides a timing signal for th e ATM switch clock circuitry. This
synchronization source is then dis tributed to all of its OC3 Interface Modules.
Each ATM Expansion Interface circuit pac k uses the received data stream from
the ATM switch to generate a timing signal. The Tone-Clock circuit p acks in the
EPNs use this signal to generate timing for all the c ircuit packs in their res pective
EPNs. All PNs, in the above mentioned scenario are desig nated the
slave
port
networks. The ATM switch is the
master
that contains the system synchronization
source. If the primary sync hronization reference does not provide a va lid timing
signal, ATM synchronization maintenance infers a switc h to the secondary
reference
.
If the primary synchronization reference is not providing a valid timing signal, the
system automatically switches to the sec ondary synchronization reference. If the
primary synchronization reference is inva lid, and if the secondar y reference does
not provide a valid timing signal or is not administered as a synchronization
reference, the switch infers that the local oscillator of the ATM switch provides the
system timing source. If the system is using the local oscillator of the ATM switch
as the system timing source bec ause the primary and sec ondary references are
providing invalid timing signals, when either the primar y or secondary reference
becomes valid ag ain, the system switches back to the primary or secondary
source. When both the primary an d secondary sourc e become valid, the system
switches to the primary sourc e, since the primary source is alw ays preferred over
the secondary source wh en both sources are equally healthy.
Figur e 9-12 depicts a simp lex ATM PNC with T1/OC3 synchronization reference
into the ATM switch.