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DSU 5600 User Manual
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Chapter 3. Test Modes
REMOTE TESTS
The DSU 5600 responds to three remote activated tests:
• Remote Digital Loopback (RDL)
• CSU Loopback (LL)
• DSU Loopback (RT)
The RDL test is initiated by a remote DSU and causes the local
DSU 5600 to loopback. The loopback point is the same as the
Loop Only point shown in Figure 3-4. This test is run to test the
end-to-end performance of the circuit.
Both the CSU Loopback and the DSU Loopback tests are acti-
vated from the telephone company diagnostic test equipment
and are used to isolate trouble on a circuit.
The CSU Loopback, commonly called the LL test, has the same
loopback points as the DTE and Loop test. It is used by the
telephone company to test the integrity of the local loop.
The DSU Loopback, commonly called the RT test, has the same
loopback point as the Loop Only test and is used by the tele-
phone company to test the operation of both the local loop and
DTE interface sections.
