Figure A-4. FT1 Repeater Network Loopback

There is one loopback available to the FT1 Repeater. The FT1 Repeater Network loopback is a digital loopback toward the CO as shown in Figure A-4. The loopback is initiated by the DDS latching loopback code for NEI Position 1 (N1000001). The NEI Position 1 latching loopback is detected in the primary DS0 of the FT1 circuit, the channel where the FT1 DP is physically installed, to control the looping of the FT1 circuit. When the FT1 circuit is looped, all DS0s in use will be looped. The DS0s in use will also be transmitted on to the customer. This loopback is also initiated by the craft interface or by the RLB push-button (when available) at the FT1-DP.

There are two loopbacks available to the FNID. The FNID network loopback loops the FT1 signal back toward the network. The FNID CPE loopback loops the FT1 signal back toward the customer.

The FNID network loopback is a digital loopback toward the CO as illustrated in Figure A-5. This loopback is initiated by the DDS latching loopback code (NEI Position 1 - N1000001 for a non- repeatered loop, or NEI Position 2 -N1000001 for a repeatered loop), by the craft interface, or by the RLB button at the FT1-DP. The NEI Position 1 latching loopback is detected in the primary DS0 of the FT1 circuit -- the channel in which the FT1 DP is physically installed -- to control the looping of the FT1 circuit. When the FT1 circuit is looped, all DS0s in use will be looped. The loopback keep alive code will be transmitted to the customer.

The FNID CPE loopback is a digital loopback toward customer premises as shown in Figure A-6. This loopback is initiated by the craft interface. When the FT1 circuit is looped, all DS0s in use will be looped. The DS0s in use will be filled with all 1s toward the network.

DSX-1 Interface

Central Office

FT1 DP

Channel Bank

HDSL

FT1

Repeater

Local Loop

FNID

DS1 Interface

Customer Premises