Testing
7-2
7924-A2-GB20-30
October 1997
Local Loopbacks
When a local loopback is enabled, the red Loop Bk LED on the front panel of
the initiating unit lights up and remains lit until the loopback is disabled.
The data flow is indicated by the bold thick arrows in
Figures 7-1
and
7-2
.
When the CO initiates a local loopback, an Alarm Indication Signal (AIS) is
received at the CP end (only if the CP end is G.703-compatible). (AIS is not
received at V.35-compatible CP units.)
Terminal
97-15514-01
CO
CP
E1 HDSL
7900
7900
E1 HDSL
7900
7900
Diagnostic
Equipment
Diagnostic
Equipment
Loop Bk
LED lights
AIS
AIS = Alarm Indication Signal
Figure 7-1.
Local Loopback, Initiated at the CO Unit
Terminal
97-15518-01
CO
CP
E1 HDSL
7900
7900
Diagnostic
Equipment
E1 HDSL
7900
7900
Diagnostic
Equipment
Loop Bk
LED lights
Figure 7-2.
Local Loopback, Initiated at the CP Unit