Appendix Aft1 Loopbacks; Figure A-1. Ft1 Loopbacks; Figure A-2. Ft1 Dp Network Loopback; Figure A-3. Ft1 Dp Cpe Loopback - ADTRAN Total Access 1500 FT1 DP Installation And Maintenance Manual

1. GENERAL
This Appendix is an overall reference to the loopback
capabilities of the ADTRAN Fractional T1 system.
Included in this Appendix are descriptions of the FT1
loopbacks and the methods for activating the FT1

loopbacks.

2. FT1 LOOPBACKS
Figure A-1 shows the application from the central
office (CO) to customer premises. The FT1 Repeater
is shown for convenience and not as a necessary part
of the FT1 network. The loopbacks shown are as
follows:
A. FT1 DP network loopback
B. FT1 DP CPE loopback
C. FT1 Repeater #1 network loopback
D. FT1 Repeater #1 customer loopback
E. FT1 Repeater #2 network loopback
F. FT1 Repeater #2 customer loopback
G. FNID network loopback
H. FNID CPE loopback
DSX-1
Interface
FT1 DP
Central
A B
Office
D4
Channel Bank
61180405L1-5A
Appendix A
FT1 Loopbacks
FT1
Repeater #1 Repeater #2
C
D
E

Figure A-1. FT1 Loopbacks

DSX-1
FT1 DP
Interface
Central
Office
D4
Channel Bank

Figure A-2. FT1 DP Network Loopback

DSX-1
Interface FT1 DP
Central
Office D4
Channel Bank

Figure A-3. FT1 DP CPE Loopback

Section 61180405L1-5, Issue 1
There are two loopbacks available to the FT1 DP:
• FT1 DP network loopback loops the FT1 signal
back to the network.
• FT1 DP CPE loopback loops the FT1 signal
back to the customer.
The FT1 DP network loopback is a digital loopback
toward the CO (see Figure A-2). This loopback is
initiated by the OCU DP latching loopback command
(N1010101) or by the Total Access 1500 craft
interface. The OCU DP latching loopback code is
detected in the primary DS0 of the FT1 circuit (the
channel where the FT1 DP is physically installed) to
control the FT1 circuit looping. When the FT1 circuit
is looped, all DS0s in use will be looped back toward
the network. AIS will be sent to the customer.
The FT1 DP CPE loopback is a digital loopback
toward customer premises as shown in Figure A-3.
This loopback is initiated by the REM LBK button
on the FNID, or by the Total Access 1500 craft
interface. When the FT1 circuit is looped, all DS0s in
use will be looped back toward the customer. All
DS0s will be transmitted on to the network.
FT1
FNID
G
F
HDSL
FNID
Local Loop
HDSL
FNID
Local Loop
T1 NIU
H
DS1
Interface
Customer
Premises
DS1
Interface
Customer
Premises
Customer
Premises
Equipment
A-1