363-206-285
Maintenance Description
Issue 3 June 2001
9-35
is automatically locked onto the protection DS1 circuit pack, and the automatic
lock is reported as a minor alarm. The automatic lock can be reset manually using
the switch-ls command. It resets automatically at midnight or if the affected
DS1 circuit pack is replaced. The DDM-2000 OC-3 Multiplexer supports
unprotected equipment configurations.
The DS1 protection circuit pack is automatically provisioned with the same user-
settable options as the service DS1 circuit pack it protects except for the line
build-out (LBO) value which is set by hardware switches (not by CIT or TL1).
Synchronization Reference Protection 9
In external timing and line timing modes, the synchronization references are 1×1
protected. If neither reference is available, the system automatically switches to
"holdover" timing mode. When the TG is provisioned for synchronization
messaging, the system can determine the quality of the line timing references by
reading the synchronization messages in the OC-N transport overhead bytes. If
the quality is not adequate, the TG will switch to holdover until manually switched
to a good reference.
If automatic synchronization reconfiguration is enabled, the TG will automatically
select the highest quality reference. See "Synchronization Messaging" in Section
5 and, "Transmission and Synchronization Interfaces" and the set-sync
command in Section 11, "Commands and Reports."
The system can be provisioned to revertive or nonrevertive timing mode
switching. The default is revertive. If provisioned for revertive mode switching, the
system automatically switches from holdover mode to the provisioned timing
mode (external timing or line timing) when an unprotected timing reference failure
clears. If provisioned for nonrevertive mode switching, the system must be
manually switched from holdover mode to the provisioned timing mode (external
timing or line timing) when an unprotected timing reference failure clears. Refer to
the rtrv-sync, set-sync and switch-sync commands in Section 11,
"Commands and Reports."
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