Knowledge Base

patlooptest can be used to test ports on any of Digium's E1/T1 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 an E1/T1 loopback cable into the port to be tested.

1. With the system powered off, confirm that the board jumpers are set appropriately for E1 mode or T1 mode. (Refer to the user's manual for the interface card.)

2. Use zttool (or dahdi_tool) to confirm that the span is "OK" (green alarm):

   zttool
or
   dahdi_tool

3. Make a backup of /etc/zaptel.conf (or /etc/dahdi/system.conf).

4. Configure the span(s) as follows.

For E1 mode, /etc/zaptel.conf (or /etc/dahdi/system.conf) should contain:

   span=1,0,0,ccs,hdb3,crc4
   clear=1-31
   # for TE2xx and TE4xx, uncomment the following two lines
   # span=2,0,0,ccs,hdb3,crc4
   # clear=32-62
   # for TE4xx, uncomment the following four lines
   # span=3,0,0,ccs,hdb3,crc4
   # clear=63-93
   # span=4,0,0,ccs,hdb3,crc4
   # clear=94-124

For T1 mode, /etc/zaptel.conf (or /etc/dahdi/system.conf) should contain:

   span=1,0,0,esf,b8zs
   clear=1-24
   # for TE2xx and TE4xx, uncomment the following two lines
   # span=2,0,0,esf,b8zs
   # clear=25-48
   # for TE4xx, uncomment the following four lines
   # span=3,0,0,esf,b8zs
   # clear=49-72
   # span=4,0,0,esf,b8zs
   # clear=73-96

5. Use ztcfg (or dahdi_cfg) to configure the channels:

   ztcfg -vvv
or
   dahdi_cfg -vvv

6. Make the tests, including patlooptest:

   cd /usr/src/zaptel/
   make tests
or
   cd /usr/src/dahdi-linux-complete-N.N.N+N.N.N/tools/
   make tests

7. Run patlooptest:

   ./patlooptest /dev/zap/1 300
   Going for it...
or
   ./patlooptest /dev/dahdi/1 300
   Going for it...

(To run patlooptest on each of four E1 spans:

   ./patlooptest /dev/zap/1 300
   ./patlooptest /dev/zap/32 300
   ./patlooptest /dev/zap/63 300
   ./patlooptest /dev/zap/94 300
or
   ./patlooptest /dev/dahdi/1 300
   ./patlooptest /dev/dahdi/32 300
   ./patlooptest /dev/dahdi/63 300
   ./patlooptest /dev/dahdi/94 300

To run patlooptest on each of four T1 spans:

   ./patlooptest /dev/zap/1 300
   ./patlooptest /dev/zap/25 300
   ./patlooptest /dev/zap/49 300
   ./patlooptest /dev/zap/73 300
or
   ./patlooptest /dev/dahdi/1 300
   ./patlooptest /dev/dahdi/25 300
   ./patlooptest /dev/dahdi/49 300
   ./patlooptest /dev/dahdi/73 300
)

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

The second parameter is an optional timeout (e.g., 300), measured in seconds.

patlooptest should complete without displaying any errors. If there are errors, it may indicate that the card or port is bad. However, errors could also be caused by interrupt misses or a faulty loopback plug.

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