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DS1 DIAGNOSTICS
DS1 Line Loop
AIS
EQUIPMENT
The DS1 diagnostics described below include link-level diagnostic tests
that affect the entire T1 link, or the DS1 (Digital Signal Level 1). Use
these tests when you suspect that a problem is impairing data on all
channels. Some of these tests can be controlled only via the Supervisory
terminal, while others can also be controlled via the front panel switches.
If you initiate a DS1 diagnostic while a DS0 diagnostic
is in progress, the DS0 diagnostic is terminated.
DS1 Line Loop, illustrated in Figure 4-5, activates the local CSU's DS1
Line Loopback function. This tests the local CSU's network interface cir-
cuitry and the T1 link by transmitting a remotely-generated test message
through the remote CSU to the local CSU and looping it back to the test
equipment for verification. No minimum pulse density is maintained.
This test can be controlled only via the Supervisory terminal, using the
Line Loop function. To perform this test, refer to Table 4-1.
Step
1.
To prevent data loss, suspend operation of all associated digital-terminating
equipment.
2.
Connect the test equipment to the remote CSU's test jacks, as shown.
3.
Initiate Line Loop at the local CSU (on the LOOPBACKS screen). Loop Status
should be ON during the test.
4.
Generate a test message. The test equipment should receive the same mes-
sage it transmitted; if not, a problem exists.
5.
To stop the test, terminate Line Loop.
NETWORK
LOCAL CSU
FIGURE 4-5. DS1 LINE LOOP
CAUTION
TABLE 4-1. DS1 LINE LOOP
Supervisory Terminal Control
T1
CSU OUT
REMOTE CSU
CSU IN
EQUIPMENT
IN
OUT
TEST
EQUIPMENT
TESTS
4-7
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