Adjuncts and Peripherals
DS1/T1 CPE loopback jack
818
SI Installation and Upgrades
June 2004
Administering the loopback 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 that 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 315
through
Figure 317
):
•
From the 120A2 (or later) ICSU to the loopback jack
•
From the loopback jack to the smart jack (network interface point)
•
From the smart jack to the CO
The first two sections are your responsibility. The last is the responsibility of 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 loopback jack. The test allows about 10 seconds for the signal to
loop around the loopback jack and return to the DS1 circuit pack. Then it sends the results to the
management terminal and proceeds to the second part of the test.
•
The second part of the test sends the standard, 3-in-24 DS1 stress-testing 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 rate counter displays the results on the management terminal until you terminates the
test.
Always perform both parts of the test. Proceed as follows.
Checking the integrity of local equipment
Before you go any further, make sure that the problem is actually on the DS1 span by testing the
equipment that connects to the span at the near end. Test the DS1 circuit pack, and perform any needed
maintenance or repairs.
