Lucent Technologies DDM-2000 OC-3 User Manual

363-206-285
Transmission and Synchronization Interfaces
Issue 3 June 2001
5-43
Synchronization Reconfiguration Using an Externally Timed Access Ring 5
Figure 5-22a shows an externally timed access ring operating in its normal
configuration. The DDM-2000 OC-3/OC-12 Multiplexer at the CO (Site A) is
externally timed from a BITS clock referenced to a PRS traceable source (host
node). The remaining DDM-2000 OC-3/OC-12 Multiplexers are externally timed
from a BITS clock referenced to a derived DS1. The SQU message is sent to
indicate where timing is traceable to an external BITS and where it is valid to be
used.
Automatic synchronization reconfiguration is not an option for externally timed
DDM-2000 OC-3/OC-12 Multiplexers; therefore, a change in the synchronization
message will not cause an automatic synchronization reconfiguration.
The stratum level of the BITS clock at the CO (Site A) must be equal to or better
(more accurate) than the stratum level of the BITS clocks used at the other sites.
This is necessary to maintain the stratum level hierarchy.
Figure 5-22. Synchronization Reconfiguration — Externally Timed Access Ring
(Sheet 1 of 2)
SQU
SQU
SQU
SQU
DDM-2000
Site A
DDM-2000
Site B
DDM-2000
Site D
DDM-2000
Site C
BITS
CLOCK
BITS
CLOCK
BITS
CLOCK
SQU
SQU SQU
SQU
a) Synchronization Reconfiguration Example (Before Failure)
BITS
CLOCK
PRS Traceable
Source
Alternate PRS
Traceable Source

Lucent Technologies DDM-2000 OC-3 Specifications

General

Brand	Lucent Technologies
Model	DDM-2000 OC-3
Category	Multiplexer
Language	English