7-1
7925-A2-GB20-30
PRELIMINARY DRAFT
June 1997
Testing
7
Detecting a Problem
The unit can detect and report problem conditions and perform diagnostic tests.
The unit offers a number of indicators to alert you to possible problems, as
described in
Monitoring the Unit
, Chapter 6:
Front Panel LEDs
Board Status and performance statistics
Remote unit board status and performance statistics
Understanding Loopback Tests
Loopback is a diagnostic function that enables a technician to isolate equipment
on the HDSL circuit to determine where on the circuit trouble may be occurring.
Loopback takes the system off-line. Data received from E1 or V.35 application
equipment is looped back, as depicted in Figures 7-1 through 7-3.
“Local” and “remote” refer to the point at which the data is looped back. In a local
loopback the data is reflected back by the local unit (CO or CP, depending on
where the command is initiated). In a remote loopback, the data is passed on to
the remote-end unit and then reflected back.
Loopback tests may only be initiated through the system terminal.
Loopback tests may initiated from either the CO or CP side of the HDSL
connection.
