DEFINITY Enterprise Communications Server Release 7
Maintenance for R7r
555-230-126 Issue 4
June 1999
Maintenance Object Repair Procedures
9-1563SYNC (Synchronization)
9
Stratum 4 Synchronization
The system can be configured with primary and sec ondary synchronization
references (DS1 or UDS1 interface circuit pac ks) when using Stratum 4
synchronization. If this is the master synchronizatio n 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 b e used as the synchronization
reference and the second ary reference is optional:
■If the primary synchronization referenc e is not providing a valid timing
signal, the system automatically switc hes to the secondary
synchronization reference.
■If the primary synchronization referenc e is invalid and second ary
reference does not provide a vali d timing signal or is not administered as a
synchronization reference, a Tone-Clock circuit p ack provides the system
timing source.
■If the system is using the local osc illator as the timing source (both th e
primary and second ary references are providing invalid timing sig nals),
should either the primary or sec ondary reference bec omes valid again,
the system switches bac k to the primary or seconda ry source.
■When both the primary and sec ondary source bec ome valid, the system
switches to the primary sourc e, since the primary sourc e is always
preferred over the second ary source when both sources are eq ually
healthy.
If the primary synchronization referenc e is providing a valid timing signal, then
the flow of system synchronization would trav el from the DS1 interface circuit
pack in the PPN across the active PPN to EPN fiber links to the two EPNs. The
PPN DS1 interface circuit pack p rovides a timing signal for the PPN Tone-Clock
circuit pack and the PPN Tone-Clock circuit pack provides timing for all circuit
packs in the PPN. Each PPN Expansion Interface circuit p ack uses the timing
generated by the Tone-Clock circ uit pack to clock d ata from the fiber links to the
Expansion Interface circu it packs in the two EPNs. The active EPN Expansion
Interface circuit p ack uses the received data s tream to generate a timing signal.
The Tone-Clock circuit packs in the EPNs use this signal to gene rate timing for all
the circuit pac ks in their respective EPNs. The PPN, in the above mentioned
scenario, is designated the
master
port network and the EPNs are called
slave
port networks. The
master
port network is defined as the port network that
contains the system synchronization so urce. If the primary synchronization
reference does not provide a valid timing signal, Synchronization Mainten ance
will switch to the secondar y reference.

Both the primary and sec ondary

references must reside in the same port network, which may be any port network.

The PPN is the recommended location.

If TDM-CLK error 2305 is in the error log, then a slave Tone-Clock loss of signal
condition exists on the slave Tone-Clock circui t pack that has this error. If only
one loss of signal occur red, the slave Tone-Clock circuit pack is rec eiving the
timing signal from the standb y EI circuit pack (in this exa mple, the timing is