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Testing a loopback jack without a smart jack
Proceed as follows.
1. Test customer premises wiring from the ICSU, or from the MM710, to the
loopback jack, as described in the "DS1 Span Test" section.
2. Test the loopback jack-to-dumb block and dumb block-to-CO wiring
(section 2 in
loopback that "overlaps" the section of the span. Any of the following
loopbacks can do this:
555-233-116
Figure 30
through
The local ICSU's line loopback, which the DS1 service provider at
the CO end typically activates, tests, and then deactivates.
The local DS1 interface's payload loopback, which the DS1 service
provider at the CO end activates and tests.
The far-end ICSU's line loopback. Activate this test at the
management terminal by entering test ds1-loop location far-csu-
loopback-test-begin, where location is the DS1 interface circuit
pack corresponding to the loopback jack. Terminate this test by
entering test ds1-loop location end-loopback/span-test, where
location is the DS1 interface circuit pack corresponding to the
loopback jack.
Bit error counts are examined as described in the "DS1 Span Test"
section. This test only isolates problems to Section 2 wiring if there
are no problems in the wiring between the far-end CO and the far-
end ICSU. Coordinate this test with the DS1 service provider.
Failure of any of the above tests (a, b, or c) indicate a problem in
Section 2. This could mean bad loopback jack -to-"dumb" block
cabling, but is more likely to indicate a problem somewhere between
the "dumb" block and the CO. This is the responsibility of the DS1
service provider.
If the DS1 Span Test confirms that there are no problems in
Section 1, the technician should proceed as follows to avoid
unnecessary dispatch.
1. Identify and contact the DS1 service provider.
2. Inform the DS1 provider that loopback tests of the CPE wiring
to the "dumb" block (section 1) showed no problems.
3. If the far-end ICSU line loopback test failed, inform the DS1
provider.
4. Request that the DS1 provider perform a loopback test of
their portion of the Section 2 wiring by sending someone out
to loop Section 2 back to the CO at the "dumb" block.
If this test fails, the problem is in the service provider's wiring.
If the test passes, the problem is in the cable between the
loopback jack and the "dumb" block. Replace the loopback
jack.
Figure
33). This can be done using a
Issue 4 October 2002
155
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