Paradyne 8747, 8777, 8779 Telco-Initiated Payload Loopback, Telco-Initiated Remote Line Loopback

Testing

Telco-Initiated Payload Loopback

The Hotwire 8747 and 8777 Termination Units support payload loopback as specified in AT&T TR 54016 and ANSI T1.403. A Telco-initiated line loopback loops the received signal on the DSX-1 interface back to the DSX-1 interface. Framing, CRC, and FDL bits are regenerated at the point of the loopback, and BPVs are removed. DSL time slots mapped to the DSX-1 port are sent all ones.

DSL

Port All Ones

CAP CAP

Transceiver Framer

T1
LIU	DSX-1	Telco
	Port
Framer
	99-16253

Telco-Initiated Remote Line Loopback

If Remote Telco Loopback is enabled, a Telco-Initiated Line Loopback loops received data at the remote unit and passes it back to the Telco through the local unit.

The following figure shows the data flow for a remote Telco-initiated payload loopback.

		Local			Remote
	T1	CAP	CAP	CAP	CAP	T1
DSX-1	LIU			DSL		LIU
Telco Port
	Framer	Framer	Transceiver	Transceiver	Framer	Framer

DSX-1 Port

AIS

99-16626

Telco-Initiated Remote Line Loopback cannot be used in cross-connect mode.

8-12 April 2000 8700-A2-GB20-00