Paradyne 3151, Operator'S Manual

Page: 106 / 234

8. Testing
8-6
March 2001 3150-A2-GB24-10
3. From the Rem Loopback screen, press F1 to select LLBUP (Line Loopback
Up), or press F2 to select LLBDN (Line Loopback Down).
The Line Loopback sequence is sent up or downstream to the far-end CSU for
10 seconds. During this time,
Sending
appears on Line 2 of the LCD,
followed by
Command Complete
when 10 seconds have elapsed.
You can press any function key to restore the Rem Loopback screen without
affecting transmission of the loopback code.
Local Loopback Tests
The Local Loopback tests enable you to conduct circuit testing and fault isolation
for the digital line. The supported local loopback tests are:
„
Line Loopback (LLB)
„
Payload Loopback (PLB)
„
DTE Loopback (DLB)
„
Repeater Loopback (RLB)
The Line Loopback command can be activated and deactivated in response to
commands received over the network interface. The Network Interface
configuration option NET LLB controls whether the CSU responds to the
commands transmitted on the network interface to initiate LLBs (see
Appendix C,
Configuration Options
).
Local loopback tests can be aborted (Abort Command) at any time.
No more than two local loopbacks can be active at any one time. An additional
restriction prohibits certain loopbacks from running at the same time. Valid
loopback combinations listed in
Table 8-2, Valid Loopback Combinations , are
identified by YES.
F1
F2 F3
Rem Loopback:
LLBUP LLBDN
Table 8-2. Valid Loopback Combinations
LLB PLB DLB RLB
LLB N/A NO YES YES
PLB
NO N/A YES NO
DLB
YES YES N/A NO
RLB
YES NO NO N/A