Loopback Jack Fault Isolation Procedures - Avaya MCC1 Maintenance Procedures

10 If the test runs for 1 minute with an error count of 0, confirm that the 3-in-24 pattern error detector
is operating properly by entering test ds1-loop location inject-single-bit-error. This causes the
3-in-24 pattern generator on the DS1 circuit pack to inject a single-bit error into the transmit
pattern. A subsequent list meas ds1 summary location command displays the bit error count:
• If a count greater than 1 is displayed, replace the ICSU and retest.
• If the problem continues, replace the DS1 circuit pack.
11 Terminate the test by entering test ds1-loop location end cpe-loopback-jack-test. Wait about 30
seconds for the DS1 to re-frame on the incoming signal and clear DS1 facility alarms.
Loopback termination fails under the following conditions:
a The span is still looped somewhere. This could be at the loopback jack, at the ICSU, or
somewhere in the network. This state is indicated by a fail code of 1313. If the red LED
on the loopback jack is on, replace the ICSU. Re-run the test and verify that the loopback
test terminates properly. If not, replace the DS1 circuit pack and repeat the test.
b The DS1 cannot frame on the incoming span's signal after the loopback jack is powered
down. This means that there is something wrong with the receive signal into the loopback
jack from the "dumb" block or the smart jack. If the service provider successfully looped
and tested the span, up to the smart jack, this condition isolates the problem to the wiring
between the loopback jack and the smart jack. Refer to
procedures
be successfully terminated until a good signal is received. To properly terminate the test
before a good receive signal is available, enter reset board location.
12 Restore the "TX LBO" field to the original value recorded in Step 2.
13 Release the DS1 circuit pack using the release board location command.
14 Leave the loopback jack connected to the DS1 span.

Loopback Jack fault isolation procedures

This section describes the possible DS1 configurations in which the loopback jack is used. These
configurations are when:
• The DS1 provider includes a smart jack.
• No smart jack is provided at all.
• A site uses fiber multiplexers.
These configurations are separated into
Configurations without a Smart Jack on page
Configurations using a Smart Jack
The addition of the loopback jack and the presence of a smart jack divides the DS1 span into three
separate sections for fault isolation. These sections are described in
descriptions, on page 360.
Maintenance Procedures
December 2003
on page 359 for information about how to proceed in this case. The test cannot
Configurations using a Smart Jack on page 359
363.
Additional maintenance procedures
DS1 CPE loopback jack (T1 only)
Loopback Jack fault isolation
and
Table 85, DS1 span section
359