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Testing
Detecting a Problem
Understanding Loopback Tests
7915-A2-GB20-20
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 Chapter 6,
Monitoring the Unit
Board Status and performance statistics
Remote unit board status and performance statistics
Front Panel LEDs
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.
"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 (the unit that initiated the
loopback). In a remote loopback, the data is passed on to the remote (far-end)
unit and then reflected back.
Figures 7-1
through
7-4
different configurations. The bold arrows indicate the direction of data flow.
September 1997
:
illustrate how local and remote loopbacks operate in
7
7-1
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