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Section 61104020L4-5, Issue 3
61104020L4-5C
DS0 DP Loopback EOC Remapping
Upon receipt of subsequent DS0 DP loopback codes
when the D channel is disabled, the U-BR1TE V
remaps the subsequent DS0 DP loopback sequences
into the respective ISDN EOC loopback messages.
This capability will permit all downstream ISDN D
channel enabled U-BR1TEs, U-Repeaters, and
TRISDN elements to respond to standard DDS DS0
DP loopback commands via the ISDN EOC as shown
in
Figure 8
.
NOTE
For DDS circuits with the D channel disabled,
all tandem U-BR1TE elements should be
ADTRAN U-BR1TE Vs with DDS Loopback
Capability for remote end test operation to
function properly. See 2B in Figure 7. In D
channel disabled applications, older non-DDS
vintage U-BRITEs may not pass the OCU
latching loopback sequence to the IDSL OCU-R.
Upon receipt of an OCU latching loopback sequence
the U-BR1TE V passes the OCU sequence in-band
downstream to the IDSL OCU-R. U-BR1TE Vs do
not respond to the CSU latching loopback command
but simultaneously pass it through to the CSU/DSU
while mapping the NT1 EOC address. The IDSL
OCU-R reverses sealing current on its 4-wire AMI
DDS interface to place the customer CSU into
loopback upon receipt of the CSU latching loopback.
The following data sequence enables the DS0 DP,
OCU, and CSU latching loopbacks:
1. Minimum of 35 transition in progress (TIP)
bytes (X0111010).
2. Minimum of 35 loopback select code (LSC)
bytes: DS0 DP (X0000101),OCU
(X1010101), CSU (X0110001).
3. Minimum of 100 loopback enable (LBE) bytes
(X1010110).
4. Minimum of 32 far-end voice (FEV) bytes
(X1011010).
X Denotes
Don’t Care
bit - either a 1 or a 0.
If the U-interface of the U-BR1TE V is not in sync,
the unit transmits MUX-Out-of-Sync (X0011010).
Disabling DS0 DP, OCU, or CSU latching loopback
sequence:
1. Minimum of 35 TIP bytes.
or by pressing the front panel loopback button.
Front Panel Tests
The valid front panel tests in leased modes are ADR1,
CRTX, LPTX, and LPBK for all circuit positions.
NT1, ADR1-ADR6 loopback tests are valid for the
LULT mode only. ADR2 would be used to test a U-
Repeater or ADR2 and ADR3 would be used to test
TRISDN elements respectively.
All active in-band loopbacks may be disabled by
pressing the front panel loopback button once when a
test set is not connected to the bantam jacks.
Initiate Loopback at IDSL OCU-R
When used for DDS, the D4 U-BR1TE may initiate a
loopback at the IDSL OCU-R. The in-band latching
OCU loopback code is sent to loop the IDSL OCU-R
when the NT1 address is selected on SW2. To invoke
the OCU loopback at the IDSL OCU-R, press the Test
button with the front panel test knob in the NT1
address location.
Figure 8. IDSL/DDS Loopback Response
Test
Head
ISDN
RPTR
U-BR1TE
1B
U-BR1TE
1B+D
IDSL
OCU-R
D4/SLC-96
T1
Loopback Response
DS0 DP #1
DS0 DP #2
DS0 DP #3
OCU
