Testing
7-3
7924-A2-GB20-30
October 1997
Remote Loopbacks
When a remote loopback is enabled, the red Loop Bk LED on the front panel
of the remote-end unit (CO or CP) lights up and remains lit until the loopback
is disabled. The loopback LED on the initiating unit does not light.
A message appears on the remote-end unit reporting that it has been put into
loopback.
The data flow is indicated by the bold thick arrows in
Figures 7-3
and
7-4
.
When the CO initiates a remote 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
97-15515-01
CO
CP
E1 HDSL
7900
7900
Diagnostic
Equipment
E1 HDSL
7900
7900
Diagnostic
Equipment
Loop Bk
LED lights
AIS
AIS = Alarm Indication Signal
Figure 7-3.
Remote Loopback, Initiated at the CO Unit
Terminal
97-15517-01
CO
CP
E1 HDSL
7900
7900
E1 HDSL
7900
7900
Diagnostic
Equipment
Diagnostic
Equipment
Loop Bk
LED lights
Figure 7-4.
Remote Loopback, Initiated at the CP Unit