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4 61291006L2-5BSection 61291006L2, Issue 2
As an enhancement to automated testing capability,
TRDDS eliminates false error indication when
invoking NIE, CSU, or DSU loopbacks immediately
following release of OCU loopback.
TROCU DP Bidirectional Loopback Support
The TROCU DP will execute a bidirectional loopback
when performing an OCU loopback at the TROCU
DP as shown in Figure 5. If the TRDDS-R detects a
bidirectional loopback during power-up
synchronization, the TRDDS-R allows data to pass on
the four-wire interface by entering into the pass-thru
mode. This allows a standard portable DDS test set,
connected to the four-wire customer interface of the
TRDDS-R, to verify the integrity of the two-wire loop
by transmitting a test pattern and examining the
returning data for synchronization and errors. The
TROCU DP LBK LED will illuminate solid during an
OCU loopback. Refer to Figure 6 for an illustration
of the bidirectional loopback pass-thru mode.
Figure 5. OCU Loopback at the TROCU DP
5. REMOTE PROVISIONING AND
DIAGNOSTICS
Control Protocol
Remote access to provisioning and status information
is accomplished using ADTRAN Digital System 6
Message protocol, defined in Control and Diagnostic
Procedures Practice, Section 6032991-6. Digital
System 6 is supported by the TPI 108/109 and 105
portable test set and is supported by Hekimian React
2001 Release 1.900 remote test system. The TRDDS
network elements comply with ANSI T1.107-1995,
“Digital Hierarchy Format Specifications Annex G”
which allows remote provisioning, querying, and
performance monitoring via inband control of network
elements.
NOTE
The REACT 2001 GUI software Release 1.900
supports ANSI T1.107-1995.
Remote access is accomplished using a defined set of
inband DS0 byte sequences similar to the latching
loopback sequence. Commands issued through the test
system are recognized by the individual channel unit,
which responds with the appropriate byte sequences.
These inband commands may be used to verify
options via dialogs with REACT 2001 and
TPI 108/109 test sets. Unit CLEI, serial number,
provisioning, and performance information can be
retrieved remotely using the Digital System 6
protocol.
Provisioning and Status
All configuration options can be remotely viewed or
provisioned. The front panel Remote (REM) LED
indicator will Flash during control link establishment
and remains ON after the channel unit has been
remotely provisioned.
If the channel unit has been remotely provisioned, the
operator can alternate between remote configuration
If the TROCU DP bidirectional loopback is invoked after
the TRDDS-R achieves synchronization, the TRDDS-R will
not pass or receive data from the CPE or DDS test set. This
is consistent with current DDS testing methods and is
referred to as the TROCU DP bidirectional loopback normal
mode. For testing purposes, the installer may choose to
initiate the TRDDS-R to pass-thru mode. Once the
bidirectional loopback is executed in normal mode, unseat
and reseat the TRDDS-R and allow the unit to train-up.
Once trained, the TRDDS-R will revert to pass-thru mode
for further testing. Refer to Figure 7 for TRDDS operation
during bidirectional loopback in normal mode.
TROCU DP
Bidirectional
loopback
Customer
Intra-office
Figure 6. TROCU DP Bidirectional Loopback
Pass-Thru Mode
Test Unit
TRDDS-R
TROCU DP
Data
Pass-Thru
Bidirectional
loopback
DSU/CSU
TRDDS-R
TROCU DP
Open Loop
Bidirectional
loopback
X
X
Figure 7. TROCU DP Bidirectional Loopback
Normal Mode