363-206-285 Detailed Level Procedure: DLP-523
Issue 2, February 2000 Page 12 of 30
DDM-2000 OC-3 MULTIPLEXER
External - Sync Out External - Sync Out Caution! This topology can potentially create
a timing loop if synchronization messaging is
not enabled on both NE’s. In this topology both
NE’s will derive the DS1 output reference from
each other thus creating a timing loop. The NE
with access to a BITS, which has an input
reference traceable to a PRS, and is sourced
from an element other than this NE, should be
reprovisioned for External - Mult to prevent the
timing loop. If Synchronization Messaging is
enabled on both NE’s, the DS1 output
referenceinoneoftheNE’swillcarryDS1AIS
and the other NE will generate a DS1 output
carrying a framed DS1 all ones signal.
Line Timing Line Timing Caution! This topology creates a timing loop
and it is not. supported. The NE with access to
an external timing reference traceable to a
PRS, if available, should be provisioned for
External - Mult. If the reference available is an
optical reference provision to Line Timing with
the proper source using the set-sync
command. If automatic synchronization
reconfiguration is supported and enabled in a
system, both NEs will attempt to switch to
another line timing source, if available, to
prevent a timing loop.
Table E – BBF2B/BBF2C TGS/BBF4 TG3 Synchronization Provisioning
Topologies (Contd)
NE 1 NE 2 Application Comments
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