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TESTS
DS1 Network
Interface Loopback
EQUIPMENT
EQUIPMENT
FIGURE 4-8. DS1 NETWORK INTERFACE LOOPBACK
4-10
DS1 Network Interface Loopback, illustrated in Figure 4-8, tests the local
CSU and the T1 link by transmitting a locally-generated test message
through the local CSU to the remote DS1 Interface Connector and looping
it back to the test equipment for verification. Whether the local CSU
transmits framed or unframed loopback codes depends on the selection of
the loopback test code framing option.
When connected to a DS1 Interface Connector, the
DataComm 551 must be configured for manual Line
Build-Out, with 0 dB attenuation.
This test can only be controlled locally via the Supervisory terminal NI
Loop test. To perform this test, refer to Table 4-4.
TABLE 4-4. DS1 NETWORK INTERFACE LOOPBACK
Step
1.
To prevent data loss, suspend operation of all associated digital-terminating
equipment.
2.
Connect the test equipment to the local CSU's test jacks, as shown.
3.
Initiate NI Loop at the local CSU (on the LOOPBACKS screen).
4.
Wait 5 seconds after starting the test, then generate a test message. The test
equipment should receive the same message it transmitted; if not, a problem
exists.
5.
To stop the test, terminate NI Loop.
CSU OUT
CSU IN
LOCAL CSU
IN
OUT
TEST
CAUTION
Supervisory Terminal Control
T1
NETWORK
DS1 INTERFACE
CONNECTOR
EQUIPMENT
REMOTE CSU
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