Testing a loopback jack without a smart jack
Issue 4 October 2002 155555-233-116
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 Figure 30 through Figure 33). This can be done using a
loopback that “overlaps” the section of the span. Any of the following
loopbacks can do this:
■The local ICSU’s line loopback, which the DS1 service provider at
the CO end typically activates, tests, and then deact ivates.
■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 a t 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 t he far-
end ICSU. Coordinate this test with the DS1 service provider.
Failure of any of the above tests (a, b, or c) indicat e a problem in
Section 2. This could mean bad loopback jack -t o-”dumb” block
cabling, but is more likely to indicate a pr oblem 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 techni cian 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 th e CPE wiring
to the “dumb” block (section 1) showed no problems.
3. If the far-end ICSU line loopback test failed, inform the DS 1
provider.
4. Request that the DS1 provider perform a loopback test of
their portion of the Section 2 wiring by sending som eone 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 th e
loopback jack and the “dumb” block. Replace the loopback
jack.