From owner-freebsd-isdn Sat Jan 2 10:02:32 1999 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id KAA08019 for freebsd-isdn-outgoing; Sat, 2 Jan 1999 10:02:32 -0800 (PST) (envelope-from owner-freebsd-isdn@FreeBSD.ORG) Received: from mail.ppp.net (mail.ppp.net [194.64.12.35]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id KAA08011 for ; Sat, 2 Jan 1999 10:02:29 -0800 (PST) (envelope-from ernie!bert.kts.org!hm@ppp.net) Received: from casparc.ppp.net (casparc2.ppp.net [194.64.12.42]) by mail.ppp.net (8.8.8/8.8.8) with SMTP id TAA16821; Sat, 2 Jan 1999 19:02:02 +0100 Received: from ernie by casparc.ppp.net with uucp (Smail3.1.28.1 #1) id m0zwVNB-002ZjZC; Sat, 2 Jan 99 19:02 MET Received: from bert.kts.org([194.55.156.2]) (3677 bytes) by ernie.kts.org via sendmail with P:smtp/R:smart_host/T:uux (sender: ) id for ; Sat, 2 Jan 1999 18:44:03 +0100 (CET) (Smail-3.2.0.103 1998-Oct-9 #3 built 1998-Dec-9) Received: from localhost (3229 bytes) by bert.kts.org via sendmail with P:stdio/R:smart_host/T:smtp (sender: ) (ident using unix) id for ; Sat, 2 Jan 1999 18:44:14 +0100 (CET) (Smail-3.2.0.103 1998-Oct-9 #4 built 1998-Dec-26) Message-Id: From: hm@kts.org (Hellmuth Michaelis) Subject: Re: Suggestion (Was Re: Rates calculations and the U.K. ) In-Reply-To: <199901021524.QAA00394@cat.turbocat.de> from David Wetzel at "Jan 2, 1999 4:24:25 pm" To: dave@turbocat.de (David Wetzel) Date: Sat, 2 Jan 1999 18:44:14 +0100 (CET) Cc: freebsd-isdn@FreeBSD.ORG Organization: Kitchen Table Systems Reply-To: hm@kts.org X-Mailer: ELM [version 2.4ME+ PL43 (25)] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-freebsd-isdn@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org David Wetzel wrote: > > This is impossible. You need a second card (or a chipset being able to > > "listen" on the tx wires) to be able to do this for everything on a given > > bus. > > Someone told me that his ISDN card (which is in a linux box) can do this. > > Would you please explain what is possible and what not? Think about the following scenario: You have an S0 bus, an NT and two devices on the S0 bus, i.e. one ISDN telephone (TE1) and an machine running i4b (TE2): || || +--------- +------->--| R |+------>--| X || || | TE1 - ISDN telephone || +----<--| T || |+---<--| X || || +--------- || || || || +--------- +------->--| R |+------>--| X || || | TE2 - i4b machine || +----<--| T || |+---<--| X || || +--------- ^^ vv || || +------------+ | TX RX | | | | NT | The NT's TX lines is connected to every TE's RX lines, so every TE can "hear" what the NT "says": This way anybody on the S0 bus "hears" who is calling. The NT's RX lines are connected to every TE's TX lines so the NT is the _only_ (!) device, which can "hear" all the TE's TX lines: this means TE2 cannot "hear" whom TE1 is calling and vice versa. In case you want to "hear" everything on the S0 bus, you have to put a second card into the i4b machine and connect that cards RX lines to the NT's RX lines, that way you are able to "hear" what every other device sends to the NT. This is supported in i4b in the isdntrace program by means of the so called "analyze mode" which i use heavily in the development of i4b: put 2 cheap card into a 386, solder a cable (documented in cable.txt) install FreeBSD & i4b and you have an ISDN bus analyzer almost for free (in case you recognize what commercial vendors will charge you for such a device). Now, there is a mechanism specified to prevent contention of the S0 bus which involves some "echo" bits (explaining this here goes much too far, so in case you want to understand that, study the respective standards text) with which you might be able to read out the NT's RX lines on the TE side. Wether a manufacturer of a given chipset allows a programmer to access those echo bits depends on the chipset being used: the Siemens chipsets i4b currently supports do not have a mechanism built in to allow access to the echo bits. Thats it. hellmuth -- Hellmuth Michaelis hm@kts.org Hamburg, Europe We all live in a yellow subroutine, yellow subroutine, yellow subroutine ... To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-isdn" in the body of the message