Administering the loopback jack
Issue 4 October 2002 137555-233-116
Administering the lo opback jack
1. At the management terminal, enter change ds1 location, where location
is the DS1 interface circuit pack corresponding to the loopback jack.
2. Be sure the near-end CSU type is set to integrated.
3. On page 2 of the form, change the supply CPE loopback jack power
field to y.
Setting this field to y informs the technician that a loopback jack is present
on the facility and allows the technician to determine tha t the facility is
available for remote testing.
4. Enter save translation to save the new information.
Loopback testing with a smart jack
The loopback jack and smart jack isolate faults by dividing the DS1 span into 3
sections (see Figure 24, through Figure 29):
■From the 120A2 (or later) ICSU, or from the MM710, to the lo opback jack
■From the loopback jack to the smart jack (networ k interface point)
■From the smart jack to the CO
The first 2 sections are your responsibility. The last is the responsibility o f the DS1
service provider.

Testing the DS1 span from the ICSU to the

loopback jack

The DS1 span test has 2 parts.
■Checking for circuit connectivity
The first part of the test powers-up the loopback jack and sends a signal
from the DS1 circuit pack, through the wiring, to the lo opback jack. The test
allows about 10 seconds for the signal to loop a round the loopback jack
and return to the DS1 circuit pack. Then it sends the results to th e
management terminal and proceeds to the second p art of the test.
■The second part of the test sends the standard, 3-in-24 DS1 stress-tes ting
pattern from the DS1 board, through the loopback jack, and back to a bit
error detector and counter on the DS1 board. A bit-error rat e counter
displays the results on the management terminal unti l you terminates the
test.
Always perform both parts of the test. Proceed as follo ws.