How to: Perform a Pattern Loopback Test

To verify that a T1 PCI card is working properly, a loopback test can be run using a hardware loopback plug. If you need to build a loopback plug, pin 1 connects to pin 4 and pin 2 connects to pin 5. Pins are numbered left to right when the hook is underneath, and the conductors are furthest away from you. Connect the loopback plug, and run the test as described below.

Loopback plug diagram - please see:
T1 Crossover Cable

Make sure that the T1 carrier's cable is connected to the back of the Superlooper so that the carrier sees a loop back and a green on the T1. This will let them know not to disable the line.

Edit Zaptel

Next, edit the /etc/zaptel.conf file. Comment out the span information using the ‘#’ character. Enter these lines:

span=1,1,0,esf,b8zs
clear=1
clear=2
clear=3
clear=4
clear=5
clear=6
clear=7
clear=8
clear=9
clear=10
clear=11
clear=12
clear=13
clear=14
clear=15
clear=16
clear=17
clear=18
clear=19
clear=20
clear=21
clear=22
clear=23
clear=24

You must type 'clear=X' for every channel (1-24).

Next, stop asterisk and FONmon.
 

Hardware-specific Information

Sangoma

Backup and modify the wanpipeX.conf file

MASTER timing

Configure the port on the Sangoma card for Master clock

vi /etc/wanpipe/wanpipe*.conf
TE_CLOCK = MASTER

No Hardware HDLC

vi /etc/wanpipe/wanpipe*.conf
TDMV_DCHAN = 0

No Hardware Echo Cancellation

vi /etc/wanpipe/wanpipe*.conf
TDMV_HWEC = NO

Start the test

Sangoma

Stop asterisk and start the driver by itself

touch /etc/asterisk/NO_FONMON  # and don't forget to remove this file after the test is done!!

/etc/init.d/asterisk/stop OR service asterisk stop

** check to ensure wanpipe / wanrouter is fully stopped **

lsmod | egrep wanpipe

Ensure you do not see any of these:

wanpipe              1072267  194wanrouter              44347  9 wanec,af_wanpipe,wanpipesdladrv               235082  4 wanec,af_wanpipe,wanpipe,wanrouterdahdi                 193994  415 wanpipe

wanrouter start

dadhi_cfg –vvvvvv

Check your work

Verify that a green light shows on the card when the loopback plug is connected. Run ‘dahdi_tool’ and verify that the T1 is in “OK” state.

Confirm the Test Will Work

The command can be run from any directory.  Run the test for 30 seconds by specifying a last argument of 30
 

Watch for the message "going for it". If you do not see the message, the test is not working. If you do see it, only errors will be displayed after that. The prompt will return when the test is complete. If you do see errors, RMA the card.

Run the Test

You'll want to edit zaptel.conf and wanpipe1.conf to restore the original config.  (This will allow the customer to reboot the server in the morning and begin using the system, provided that the card is fine.)
 

script -c "nice -n -11 patlooptest /dev/dahdi/1 14400" loop.test

When you get back on the server in the morning, or later that evening, look through loop.test to see if there are errors during the test.