363-206-305
Maintenance Description
9-22
Issue 3 June 2000
the OC-1/OC-3/OC-12 transport overhead bytes. If the quality is not adequate, the
system will switch to holdover until manually switched to a good reference.
Automatic synchronization reconfiguration is always enabled; thus the system will
automatically select the highest quality reference. See "Synchronization
Messaging" in Chapter 5, "Transmission and Synchronization Interfaces" and the
set-sync
command in Chapter 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 out of holdover mode to 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 line timing mode when
an unprotected timing reference failure clears. Refer to the
rtrv-sync
,
set-sync
, and
switch-sync
commands in Chapter 11, "Commands and
Reports."
Loopbacks
9
The DDM-2000 FiberReach Multiplexer allows technicians to set up loopbacks on
all low- and high-speed interfaces. Low-speed DS1/DS3 electronic loopbacks,
directed toward the high-speed OC-1/OC-3/OC-12, can be individually controlled
from the CIT. DS1/DS3 facility loopbacks toward the DSX can also be set up for
DS1/DS3 signals. Active electronic loopbacks are noted by the user panel's
abnormal (ABN) indicator and in the alarm and status report. Refer to the
opr-
lpbk,opr-lpbk-t1
and
rls-lpbk-t1
commands in Chapter 11,
"Commands and Reports."
Beginning with Release 3.1 of FiberReach, the
opr-lpbk-t3
and
rls-lpbk-t3
commands are available when using the DS3 circuit packs in the
Function Units slots. Refer to Chapter 11, "Commands and Reports," for
explanations of these commands.
Front access to the OLIU optical connectors allows an easy manual OC-1, OC-3.
or OC-12 optical loopback. This loopback is set up by connecting a fiber jumper
from the OLIU output to its input. An optical attenuator is required for this
loopback.
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