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 provides a timing signal for the ATM switch clock circuitry. This
synchronization source is then distributed to all of its OC3 Interface Modules.
Each ATM Expansion Interface circuit pack uses the received data stream from
the ATM switch to generate a timing signal. The Tone-Clock circuit packs in the
EPNs use this signal to generate timing for all the circuit packs in their respective
EPNs. All PNs, in the above mentioned scenario are designated the
slave
port
networks. The ATM switch is the
master
that contains the system synchronization
source. If the primary synchronization reference does not provide a valid timing
signal, ATM synchronization maintenance infers a switch to the secondary
reference
.
If the primary synchronization reference is not providing a valid timing signal, the
system automatically switches to the secondary synchronization reference. If the
primary synchronization reference is invalid, and if the secondary 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 because the primary and secondary references are
providing invalid timing signals, when either the primary or secondary reference
becomes valid again, the system switches back to the primary or secondary
source. When both the primary and secondary source become valid, the system
switches to the primary source, since the primary source is always preferred over
the secondary source when both sources are equally healthy.
Figure 9-12
depicts a simplex ATM PNC with T1/OC3 synchronization reference
into the ATM switch.
