Timing And Synchronization - Toshiba STRATA DK14 Installation And Maintenance Manual

CO ISDN
ISDN PRI
PRI Test
Signal
Network
Jack
RJ-48C
or RJ-48X
Demarcation Point
Figure 16-30 Loop-back Test

Timing and Synchronization

The Digital Network is connected by timing clocks that synchronize the network and have various
degrees of precision (stratum levels). There are four stratum levels – 1 is the highest and 4 is the
lowest. They are associated with the following sources:
o Stratum – 1: Public Telephone Network clock
Stratum – 2: #4 ESS Toll Switches
o
Stratum – 3: #5 ESS Central Offices
o
Stratum – 4: Digital PBXs
o
In the DK424 or DK424i, one PRI, BRI, or T1 PCB can be programmed to extract the Stratum
clock signal. It uses the signal as the DK system Primary clock reference. The clock provider
should be a reliable source, such as a Telco or common carrier (AT&T). All other PRI, BRI, or T1
lines connected to the DK424 or DK424i will be synchronized to the same clock provider. If the
PRI, BRI, or T1 are not synchronized to the same clock provider, the DK424 or DK424i could
experience "slip" problems.
Timing reference assignments for PRI, BRI, and T1 are made with the Program *42 series. The
timing or synchronization program determines how the DK424 or DK424i digital voice or data
transmission path is synchronized with the far-end digital path. For proper PRI, BRI, and T1
operation, the equipment at each end of the line must be synchronized.
The DK processor time switch is synchronized as the slave to the PRI, BRI, or T1 line (Line 1 in
Figure 16-31). The DK424 or DK424i PRI, BRI, or T1 in any slot number can be assigned as the
Primary reference (Program *42-1, DATA=1 for this PRI, BRI, or T1).
If a malfunction occurs and Primary reference synchronization is lost, the DK424 or DK424i
automatically switches modes and synchronizes to the Secondary reference, provided that there is
another PRI, BRI, or T1 installed in the DK system. The Secondary reference PCB is assigned in
Program *42-2.
Strata DK I&M 6/00
ISDN PRI
CSU
(RJ-45)
Timing and Synchronization
RPTU
JP1
(LB-ON)
1.5MHz
line
Interface
LSI
JP2
(LB-ON)
ISDN Interfaces
2756
16-39