Lucent DDM-2000 OC-3 User And Service Manual page 765

DLP-503
: Detailed Level Procedure
Page 5 of 10
Table B – BBF2B/BBF2C TGS/BBF4 TG3 Synchronization Provisioning Topologies
NE 1
External - Mult
External - Sync Out
Line Timing
NOTE:
To set switch to ON, depress rocker or slide switch toward side labeled
ON in the figure. To set switch to OFF, depress rocker or slide switch
toward side labeled OFF in the figure.
NE 2
External - Sync Out
External - Sync Out
Line Timing
DDM-2000 OC-3 M
Issue 2, February 2000
Application Comments
This topology is used to distribute network timing to a
target location from a location with access to a
synchronization reference. The NE provisioned for
External - Mult, is providing timing to the NE provisioned
for External - Sync Out, which in turn generates a DS1
output reference regenerated from the optical interface
shared by both NE's. This DS1 output is used to provide a
synchronization reference to a BITS.
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 reference in one of the NE's will carry DS1
AIS and the other NE will generate a DS1 output carrying
a framed DS1 all ones signal.
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.
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