*---------------------------------------------------------------------------
 *
 *      Custom cable to trace an ISDN S0 bus with two passive (!) ISDN boards
 *	---------------------------------------------------------------------
 *
 *	$Id: cable.txt,v 1.1.1.1 2001/01/06 13:00:29 martin Exp $ 
 *
 * $FreeBSD$
 *
 *      last edit-date: [Mon Dec 13 21:55:42 1999]
 *
 *	-hm	documentation of analyze mode
 *
 *---------------------------------------------------------------------------*/

The cable consists of a RJ-45 plug with both tx and rx connected and
two jacks; the tx cables from the plug are wired to one jack and the
rx cables from the plug are wired to the other jack.

The computer must be equipped with two (!) supported passive cards and
the cable from one card is plugged into one of the jacks while the cable
to from the other card is plugged into the other jack.

Now one card monitors the tx part of the S0 bus and the other card 
monitors the rx part.

Which card functions as the rx side and which as the tx side can be
specified as options to the isdntrace utility (-R and -T) which has
to be run in analyzer mode (-a) to support this configuration.


                                              1
                                              2
                                              3
                               +--------------4     receiving-side board
  S0-bus                    +--|--------------5     in computer (jack for
  to analyze                |  |              6     cable to passive controller)
               8            |  |              7
               7            |  |              8
    transmit - 6------------|--|--+
    receive  - 5------------+  |  |
    receive  + 4---------------+  |
    transmit + 3------------+     |
               2            |     |           1
               1            |     |           2
  plug into                 |     |           3
   S0 bus                   +-----|-----------4    transmitting-side board
                                  +-----------5    in computer (jack for
                                              6    cable to passive controller)
                                              7
                                              8



           RJ-45 plug                        RJ-45 jack
        view from the front              view from the front
    cable goes out to the rear

          /--------- /                      ----------
         | 87654321 |                      | 12345678 |
         |__      __|/                     |/_      /_|
            |____|/                           |/___|