363-206-295
Maintenance Description
9-20 Issue 1 December 1997
Equipment Protection 9
The 3DS3, 3STS1E, BCP3 TSI, and TG circuit packs are 1x1 protected and use
nonrevertive switching. Green ACTIVE LEDs are provided on the faceplates of
these circuit packs to indicate which circuit packs are active (carrying service).
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-12 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, "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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