DEFINITY Enterprise Communications Server Release 7
Maintenance for R7r
555-230-126 Issue 4
June 1999
Additional Maintenance Procedures
6-21DS1 CPE Loopback Jack (T1 Only)
6
A problem can exist in 1 or b oth of the 2 sections. The field technic ian is
responsible for finding and correcting p roblems in section 1 and the l oopback
cable portion of se ction 2. The DS1 service provider is resp onsible for finding
and correcting problems in the majority of section 2. Testing is divided into 2
steps.
1. Test customer premises wiring (section 1 in Figure 6-4 ) from the ICSU 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 6-4). This can be done using a loopback that
“overlaps” the sec tion of the span. Any of the following loop backs can d o
this:
a. The local ICSUs line loopback, whic h is typically activated , tested,
and then deactivated by the DS1 service provider at the CO end.
b. The local DS1 interface’s payload loopback, ac tivated and tested
by the DS1 service provider at the CO end.
c. The far-end ICSU’s line loopbac k. 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 desc ribed in the “DS1 Span Test” section.
This test only isolates problems to section 2 wir ing if there are no
problems in the wiring b etween 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 b ad loopback j ack -to-”dumb” block
cabling, b ut is more likely to indicate a prob lem 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 te chnician should proc eed as
follows to avoid unnecessary d ispatch.
■Identify and contac t the DS1 service provider
■Inform the DS1 provider that loopb ack tests of the CPE
wiring to the “dumb ” block (sectio n 1) showed no problems
■If the far-end ICSU line loopbac k test failed, inform the DS1
provider
■Request that the DS1 provider perform a l oopback test of
their portion of the section 2 wiring by sending someone out
to loop section 2 bac k to the CO at the “dumb” block.
If this test fails, the problem is in the servic e provider’s
wiring.
If the test passes, the problem is in the cable between the
loopback jac k and the “dumb” block. Replace the loop back
jack.