DLP-523: Detailed Level Procedure 363-206-285
Page 9 of 30 Issue 2, February 2000
DDM-2000 OC-3 MULTIPLEXER
Table E – BBF2B/BBF2C TGS/BBF4 TG3 Synchronization Provisioning
Topologies
NE 1 NE 2 Application Comments
Free Running Free Running This topology is not supported. Both systems
are operating asynchronously from each other.
Free Running Line Timing This topology is allowed but results in having a
SONET subnetwork operating asynchronously
with respect to other NE’s in the network. The
NE’s deriving timing off the NE provisioned for
Free Running will be synchronized to it but not
to a PRS on the network. If automatic
synchronization reconfiguration is supported
and enabled in a system, the NE 2 system will
attempt to switch to another better quality line
timing source, if available.
Free Running Line Timing - Sync Out This topology, although not recommended,
results in having a SONET subnetwork
operating asynchronously with respect to
other NE’s in the network. The NE’s deriving
timing off the NE provisioned for Free Running
will be synchronized to it but not to the rest of
the network. The DS1 timing output is
normally used to synchronize other NE’s to a
PRS. In this topology the timing of the Free
Running NE is being distributed by the use of
the DS1 output timing reference in the
absence of Synchronization Messaging. In the
presence of Synchronization Messaging, the
DS1 output will carry DS1 AIS. If automatic
synchronization reconfiguration is supported
and enabled in a system, the NE 2 system will
attempt to switch to a better quality line timing
source, if available.
Free Running External - Mult This timing topology is not supported. The two
network elements will be operating
asynchronously from each other.
Free Running External - Sync Out This timing topology is not supported. The two
network elements will be operating
asynchronously from each other.
External - Mult Line Timing This topology is used when one of the NE’s
does not have access to an external
synchronous reference and needs to be
synchronized to an NE whose timing is
traceable to a PRS. The NE provisioned for
Line Timing will derive its timing from the NE
provisioned for External - Mult timing thus
operating synchronously with that respective
NE. The NE provisioned for External - Mult
timing could use its DS1 output to distribute its
incoming DS1 timing reference to other
shelves in the bay to conserve ports on the
BITS.
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