Avaya S8700 Maintenance Manual page 2233

SYNC (Port-Network Synchronization)
Stratum-3 Synchronization
Since the clock module on the TN2312 does not support synchronization with an
external Stratum-3 clocking device, you may provide Stratum-3 clocking for a
S8700 Media Server system by using the TN780 Tone-Clock circuit pack in a
non-IPSI-connected port network. To bring in the external Stratum-3 clocking
signals into the TN780, a processor carrier is needed. This new EPN control
carrier will replace the processor carrier in the old PPN converted to EPN 1. The
Stratum-3 clocking must come into Port Network #1 because the S8700
Multi-Connect software has the Stratum-3 clocking hard-coded to this port
network.
Stratum-4 Synchronization
An EPN can be configured with primary and secondary synchronization
references (DS1 or UDS1 Interface circuit packs) when using Stratum-4
synchronization. If this is the master synchronization source for the network, then
its local oscillator is used and no DS1s are used as references. If this system is a
slave in the network, a primary reference must be used as the synchronization
reference and a secondary reference is optional:
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 secondary reference
does not provide a valid timing signal or is not administered as a
synchronization reference, an IPSI's Tone-Clock circuit or a Tone-Clock
circuit pack provides the EPN's timing source.
If the system (PN for S8700 Media Server systems) is using the local
oscillator as the timing source (both the primary and secondary references
are providing invalid timing signals), should either the primary or secondary
reference becomes valid again, the system (PN for S8700 Media Server
systems) switches back to the primary or secondary source.
When both the primary and secondary source become valid, the system
(PN for S8700 Media Server systems) switches to the primary source,
since the primary source is always preferred over the secondary source
when both sources are equally healthy.
Synchronization Troubleshooting
For Stratum-4 operation, major and minor alarms indicate that there is a problem
with the system synchronization references. These alarms will be resolved when
the alarmed synchronization reference is restored.
The change synchronization command allows primary and secondary
references to be administered per cabinet.
555-233-143 Issue 1 May 2002 8-1511