Date: Wed, 30 Dec 1998 20:15:45 +0100 (CET) From: hm@kts.org (Hellmuth Michaelis) To: gax43544@icn.siemens.de (Andreas Gaertner) Cc: freebsd-isdn@FreeBSD.ORG Subject: Re: isdntrace Message-ID: <m0zvR5t-00000DC@bert.kts.org> In-Reply-To: <Pine.GSO.3.96.981230172944.1592W-100000@koerk> from Andreas Gaertner at "Dec 30, 1998 5:33:40 pm"
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Andreas Gaertner wrote: > recently i tried out the isdntrace and noted that using the string > isdntrace -f /var/tmp/isdn.trace produces following output every ten > seconds with no traffic occuring during the trace: > > -- NT->TE - unit:0 - frame:000031 - time:30.12 17:31:53.924800 - length:4 > ------ > Dump:000 00 9f 01 05 .... > Q921: SAP=0 (Call Control), R, TEI=79, S-Frame: RR N(R) 2 PF The exchange asks "Hey, Terminal Equipment, are you still alive?" and we answer "Yes, i am". This goes for about 10 seconds after the last active connection has been closed, at that point the exchange shuts down layer 2 and 1 (in case you didn't ordered a constantly activated bus). This is the protocol mechanism which prevents you from being charged horrible amounts of money in case you have an active connection going on and someone pulls the plug. Folks, in case you want to use isdntrace for something serious, have a look in the file "misc/Resources" and fetch yourself the ITU standards Q.921 and Q.931 from one of the links (www.etsi.org is missing in that file, they opened up their site recently and anybody can now download much of the ETSI standards there for free), print them out and have them ready when you start looking at isdntrace output. 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
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