ADC HDSL4 Manuel D’Utilisation

 is a graphical representation of the various loopback configurations with the associated 

GNLB commands shown. Refer to 

 for a description of these commands. 

NLOC

1111000

4-in-7

DSX-1 signal is looped back to the network at 
the H4TU-C.

X

X

X

NREM

1110000

3-in-7

DSX-1 signal is looped back to the network at 
the H4TU-R.

X

X

X

NDU1

110000

2-in-6

Signal is looped back to the network at H4D1.

X

X

X

CDU1

111100

4-in-6

DS1 signal from customer is looped back to the 
customer at H4D1.

X

X

X

NDU2

111000

3-in-6

Signal is looped back to the network at H4D2.

X

X

X

CDU2

111110

5-in-6

DS1 signal from customer is looped back tot he 
customer at H4D2.

X

X

X

D1LB

Dual loopback at H4D1.

X

D2LB

Dual loopback at H4D2.

X

CLOC

1111100

5-in-7

DS1 signal from the customer is looped back to 
the customer at the H4TU-R.

X

X

X

CREM

1111110

6-in-7

DS1 signal from the customer is looped back to 
the customer at the H4TU-C.

X

X

X

COLB

Dual loopback at the H4TU-C. DSX-1 signal is 
looped back to the network at the H4TU-C and 
DS1 signal from the customer is looped back to 
the customer at the H4TU-C.

X

RULB

Dual loopback at the H4TU-R. DSX-1 signal is 
looped back to the network at the H4TU-R and 
DS1 signal from the customer is looped back to 
the customer at the H4TU-R.

X

SMJK LpUp

(PL)

11000

2-in-5

SmartJack Loopup or NID payload (PL) code. 
Invokes H4TU-R loopback towards network.

X

SMJK LpUp

(ESF-DL)

1111-1111-
0100-1000

SmartJack Loopup or NID (ESF-DL) code. 
Invokes H4TU-R loopback towards network.

X

SMJK LpDn

(PL)

11100

3-in-5

SmartJack Loopdown or NID payload (PL) code. 
Removes SMJK, NLOC, NREM, CLOC, and 
CREM.

X

SMJK LpDn

(ESF-DL)

1111-1111-
0010-0100

SmartJack Loopdown or NID (ESF-DL) code. 
Removes SMJK, NLOC, NREM, CLOC, and 
CREM.

X