DS1 CPE Loopback Jack (T1 Only)
Issue 1 May 2002
5-13555-233-143
A problem can exist in one or both of the two sections. The field technician is
responsible for finding and correcting problems in section 1 and the loopback
cable portion of section 2. The DS1 service provider is responsible for finding and
correcting problems in the majority of section 2. Testing is divided into two steps:
1. Test customer premises wiring (section 1 in Figure 5-4 on page 5-11) from
the ICSU to the loopback jack as described in ‘‘DS1 Span Test’’ on page
5-3.
2. Test the loopback jack-to-”dumb” block and ”dumb” block-to-CO wiring
(section 2 in Figure 5-4 on page 5-11). This can be done using a loopback
that “overlaps” the section of the span. Any of the following loopbacks can
do this:
a. The local ICSU’s line loopback, which is typically activated, tested,
and then deactivated by the DS1 service provider at the CO end.
b. The local DS1 interface’s payload loopback, activated and tested by
the DS1 service provider at the CO end.
c. The far-end ICSU’s line loopback. This test is activated at the
management terminal by entering test ds1-loop location
far-csu-loopback-test-begin. The test is terminated by entering
test ds1-loop location end-loopback/span-test. 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.
If any of the above tests (a, b, or c) fail, a problem is indicated 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.
■ Identify and contact the DS1 service provider.
■ Inform the DS1 provider that loopback tests of the CPE wiring
to the “dumb” block (section 1) showed no problems.
■ If the far-end ICSU line loopback test failed, inform the DS1
provider.
■ 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.
To Next Page
Loading...
