363-206-285 Detailed Level Procedure: DLP-523
Issue 2, February 2000 Page 10 of 30
DDM-2000 OC-3 MULTIPLEXER
External - Mult Line Timing - Sync Out This topology is used when one of the NE’s
does not have access to an external
synchronous reference, needs to be
synchronized to an NE whose timing is
traceable to a PRS, and timing is needed to be
distributed where NE 2 is located. The NE
provisioned for Line Timing - Sync Out will
derive its timing from the NE provisioned for
External - Mult timing thus operating
synchronously with that respective NE. Its
DS1 output could serve as a reference to
distribute timing to a BITS in that CO. 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.
External - Sync Out Line Timing Caution! This topology might create a timing
loop. In this topology the NE provisioned for
Line Timing will derive its timing from the NE
provisioned for External - Sync Out timing thus
operating synchronously with that respective
NE. The NE provisioned for External - Sync
Out should be reprovisioned for External - Mult
to prevent the potential timing loop existing in
the actual provisioning. If Synchronization
Messaging is enabled on both NE’s, the DS1
output reference of the NE provisioned for
External - Sync out will carry an unframed all
ones DS1 signal (DS1 AIS) in the present
topology. If automatic synchronization
reconfiguration is supported and enabled in a
system, both NEs will attempt to break the
potential timing loop. NE 1 will attempt to
break the loop by inserting DS1 AIS on its DS1
output port. NE 2 will attempt to switch to
another line timing source, if available, to
prevent the timing loop.
Table E – BBF2B/BBF2C TGS/BBF4 TG3 Synchronization Provisioning
Topologies (Contd)
NE 1 NE 2 Application Comments
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