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Maintenance
4-193170-A2-GB20-20 December 1996
Starting a Data Terminal Loopback
The Data Terminal Loopback command (DTLB) loops
the data received from the selected port, for all DS0
channels allocated to the port, back out of the port. This
loopback occurs after the data passes through the port
circuitry but before it reaches the E1 framer.
To perform a Data Terminal loopback,
1.
Press F2 to select T
est from the top-level menu
screen.
2. From the T
est screen, press F2 to select Lpbk.
F1
Test:
Rlpbk Lpbk Ptrns
F2
F3
3. From the Loopback screen, press four times
to display the DTLB selection on the screen.
4.
Press F3 to select DTLB.
F1
Loopback:
RLB DCLB DTLB
F2
F3
5. From the DTLB screen, press the Function key for
the port for which you want to perform the data
terminal loopback. Use the scroll keys, if
necessary.
F1
Loopback: DTLB
Prt1 Prt2 Prt3
F2
F3
Test Started appears on Line 2. If a Data
Terminal loopback is already in progress, the
Already Active
message appears. If an invalid
combination of loopbacks is in progress, the error
message
Invld T
est Combo
appears (see
Table 4-8 for valid loopback test combinations).
Aborting Loopbacks
The
Abort Loopback command stops all loopback tests
or any selected loopback test currently active on the E1
DSU/CSU.
To abort one or more loopback tests,
1.
Press F2 to select T
est from the top-level menu
screen.
2. From the T
est screen, press F2 to select Lpbk.
F1
Test:
Rlpbk Lpbk Ptrns
F2
F3
3.
From the Loopback screen, press F1 to select
Abort.
F1
Loopback:
Abort LLB PLB
F2
F3