ADTRAN DSU IV ESP, User Manual

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Chapter 13. Testing and Troubleshooting
61204011L1-1 DSU IV ESP User Manual 13-19
DBU CONNECTION
When the DSU IV ESP is equipped with a dial backup option, the
DBU C
ONNECTION
option appears as one of the T
EST
menu
selections. This test allows the dial backup network to be tested
while data is transmitted on the main line. See Figure 13-12.
When this option is selected, choose a stored number, enter a
number to dial, or redial the last dialed number. After establishing
DBU connection, the DSU IV ESP designated at the answer unit is
placed into loopback and a test pattern is transmitted from the
originate unit to the answer unit. Receive data is checked for errors
and the results displayed on the front panel. While running this
test, errors may be injected by pressing
2 and cleared by pressing 1 .
During the DBU test, the T
EST
LED is On.
Figure 13-12. DBU Connection Test
When running at a subrate over a 56k or 64k loop (or a 64k loop with
Scrambler activated), the DSU will not send data during a DBU test.
The DBU Answer Test option must be enabled. Enabling DBU Answer
test does not affect the unit during dial backup.
DDS
Switched
DTE
LOCAL
DSU/CSU
DBU
DTE
LOCAL
DSU/CSU
Answer Orig
M
U
X
M
U
X
DBU