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Loopback test how to

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Last Modified: 2013-11-12
Hi,
How do I create a loopback cable for my ISDN card? and
How do I run loopback tests?
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Commented:
I got this from digium for a problem I was having a while ago.


/********
First you will need to make a loopback plug, you can make a loopback plug by taking a rj45
jack and running a wire from pin 1 to pin 4 and a wire from pin 2 to pin 5.
/********
If the card lights up green we will proceed with a quick edit of you zatpel.conf:

span = 1,0,0,ccs,hdb3,crc4
clear = 1-31
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Then run ztcfg -vv to configure the channels.
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Now you can build and run the tests.

cd /usr/src/zaptel
make tests

./patlooptest /dev/zap/1 60
Going for it...
/********
If nothing happes then you card should be fine
If it spews a bunch of errors, then something is wrong
/*******

Author

Commented:
Thanks! :)
Can't wait to try it out.
Steven

Author

Commented:
Hi,
When I pluggged in the loopback device I made the light on the card just stayed red....
Steven
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Commented:
You might need to make the changes to the zaptel configuration and reconfigure the card depending on what the existing configuration was.
Give that a go first otherwise I would contact digium directly as they might have some more diagnostic tests you can run since there is a new major version of zaptel since I received these inctructions and you have a newer model card then I have aswell.

Author

Commented:
I will try contact digium.
I was surprised that the line synced fine after un-plugging and re-plugging it - I could see that each of the b-channels was restarting 1 at a time. Is there a way to do an "indepth" restart like this from console / CLI? or did that come from Telco side? - it looks the same as when I ask them to reload their equipment.
Thanks
Steven
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Commented:
I dont know of a way of doing it from the console. Perhaps stopping asterisk and reloading zaptel might do it.

Author

Commented:
Fron Digium:

The patlooptest can be used to test ports on any of Digium's T1/E1 digital interface cards. This test transmits a bit pattern and listens for the same bit pattern to be received, comparing the results. To run the test, plug a T1/E1 loopback cable into the port to be tested.

After installing the RJ45 connector zttool should report green on the span.Use zttool to confirm that the span is "OK" (green alarm):
  zttool

If it is not green the T1/E1 loopback cable was made incorrectly.

Then configure the span as follows.

For a T1, /etc/zaptel.conf should contain:
  span = 1,0,0,esf,b8zs
  clear = 1-24

For an E1, /etc/zaptel.conf should contain:
  span = 1,0,0,ccs,hdb3,crc4
  clear = 1-31

Then, to configure the channels, run:
   ztcfg -vv

Now, make the tests, including patlooptest:
  cd /usr/src/zaptel
  make tests

Run the patlooptest:
  ./patlooptest /dev/zap/1 60
  Going for it...

The first parameter to patlooptest is the channel on which to run the test (e.g., /dev/zap/1 ). The test should be run on the first channel of the span in question.

The second parameter is an optional timeout (e.g., 60).

The test should complete with no errors. If there are errors, it may indicate that the card or port is bad. However, errors could also be caused by IRQMisses or a faulty loopback plug.

If patlooptest does not terminate after the timeout, the card is probably not taking any interrupts.

How do I know if I am T1 or E1?
The card specs say :

powerful interface supporting voice and data transmission over T1, E1, and
Primary Rate ISDN (PRI) connections

I've always known it as PRI. How do I find out if I'm T1 or E1?

Steven

Author

Commented:
Hi,
I checked and triple checked my loopback connector.
1 - 4 and 2 - 5.
I used a cable tester, and asked someone else to check it again for me incase I was missing something stuid.... I'm sure it's right.

I plug it in and the light flashes red.

I stopped Asterisk and re-started zapte - still flashing red.

Steven
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Commented:
T1 has 24 lines and is most common in the USA while E1 has 30 lines and is mainly a european standard. On the card I have there is a jumper on the card itself to switch between T1 and E1.

You could post a photo of the connector if you would like me to check it.

Author

Commented:
we have 30 b-channels and 1 D channel - so I guess E1....
I have 2 photos of the card. Unfortunately neither of them include the jumper.
The light doesn't go green with the loopback in tho. and zttool is empty.
Steven
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Author

Commented:
Hmm...
It works fine most of the time. :)
lol. I will make a new one just incase.
I have tested it with a cable tester ... is showed 1, 2, 4 and 5
Steven

Author

Commented:
Still awaiting Digium's respnse.
Steven

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