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<TITLE>RE: [Megaco] Re: Event descriptor handling for static logic interfaces like CAS</TITLE>
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<P><FONT SIZE=2>Thomas,</FONT>
</P>
<P><FONT SIZE=2>The function you want already exists in the package. Each one of the line signalling events in both ICAS and BCAS have descriptions that contain the following:</FONT></P>
<P><FONT SIZE=2>The event is reported by the MG if either the timed transition to this line signal is detected or the line signal already exists.</FONT></P>
<P><FONT SIZE=2>This means that the strict=state behavior is already inherent in these events. I see no problem with this, and no need for a change to these packages.</FONT></P>
<P><FONT SIZE=2>Kevin</FONT>
</P>
<P><FONT SIZE=2>-----Original Message-----</FONT>
<BR><FONT SIZE=2>From: Thomas Voith [<A HREF="mailto:Thomas.Voith@alcatel.de">mailto:Thomas.Voith@alcatel.de</A>] </FONT>
<BR><FONT SIZE=2>Sent: Thursday, October 02, 2003 4:00 AM</FONT>
<BR><FONT SIZE=2>To: Christian Groves</FONT>
<BR><FONT SIZE=2>Cc: megaco@ietf.org; ITU-SG16@external.cisco.com</FONT>
<BR><FONT SIZE=2>Subject: Re: [Megaco] Re: Event descriptor handling for static logic interfaces like CAS</FONT>
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<BR>
<P><FONT SIZE=2>Hello Christian</FONT>
</P>
<P><FONT SIZE=2>I want both, </FONT>
<BR><FONT SIZE=2>- strict parameter for CAS Line signals and in future for all 'static'signalling interfaces.</FONT>
<BR><FONT SIZE=2>- optionally a default strict="state" to shorten the Events Descriptor</FONT>
</P>
<P><FONT SIZE=2>In my opinion, this should be used for all 'static' signalling interfaces. With 'static' I mean that this interface has always a state, when MG receives an EventsDescriptor from MGC. For synchronizing the states from MGC with MG the strict mechanism is very useful. Doing the same with EventBuffer, Embedded Descriptor </FONT></P>
<P><FONT SIZE=2>is much more complex and increases extreme with the number of possible states on the interface.</FONT>
</P>
<P><FONT SIZE=2>Note: This 'strict' parameter is just used by MG to determine, whether a Notify</FONT>
<BR><FONT SIZE=2> for the existing state on the interface has to be sent or not.</FONT>
<BR><FONT SIZE=2> Further on normal event handling applies.</FONT>
<BR><FONT SIZE=2> This approach has the advantage, that EventBuffer and Embedded can still be used</FONT>
<BR><FONT SIZE=2> in addition.</FONT>
<BR><FONT SIZE=2> </FONT>
<BR><FONT SIZE=2>For all 'dynamic' events like pulses, DTMF, SPCM, normal event handling applies.</FONT>
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<P><FONT SIZE=2>Best regards</FONT>
</P>
<P><FONT SIZE=2>Thomas</FONT>
</P>
<BR>
<BR>
<P><FONT SIZE=2>Christian Groves wrote:</FONT>
<BR><FONT SIZE=2>> </FONT>
<BR><FONT SIZE=2>> Hello Thomas,</FONT>
<BR><FONT SIZE=2>> </FONT>
<BR><FONT SIZE=2>> Are you wanting a general purpose mechanism such as the off-hook one </FONT>
<BR><FONT SIZE=2>> or do you just want the default stated for H.248.26 and H.246.ICASC?</FONT>
<BR><FONT SIZE=2>> </FONT>
<BR><FONT SIZE=2>> Kevin Boyle is the editor of these he may have some opinion on this.</FONT>
<BR><FONT SIZE=2>> </FONT>
<BR><FONT SIZE=2>> Its always possible to make amendments to existing recommendations. </FONT>
<BR><FONT SIZE=2>> Bring in a contribution for consideration to SG16 or propose a </FONT>
<BR><FONT SIZE=2>> detailed solution on the Megaco list for experts to review. If they </FONT>
<BR><FONT SIZE=2>> are agreeable then the change will be added.</FONT>
<BR><FONT SIZE=2>> </FONT>
<BR><FONT SIZE=2>> Regards, Christian</FONT>
<BR><FONT SIZE=2>> </FONT>
<BR><FONT SIZE=2>> Thomas Voith wrote:</FONT>
<BR><FONT SIZE=2>> </FONT>
<BR><FONT SIZE=2>> > Dear list-members,</FONT>
<BR><FONT SIZE=2>> ></FONT>
<BR><FONT SIZE=2>> > H.248.26 and in H.248.ICAS I miss a feature, which has been used </FONT>
<BR><FONT SIZE=2>> > already for On-Hook, Off-Hook the 'strict' parameter.</FONT>
<BR><FONT SIZE=2>> ></FONT>
<BR><FONT SIZE=2>> > All interfaces, which have static states, should implement such a </FONT>
<BR><FONT SIZE=2>> > mechanism.</FONT>
<BR><FONT SIZE=2>> ></FONT>
<BR><FONT SIZE=2>> > The problem is that the EventsDescriptor EventBufferDescriptor or an </FONT>
<BR><FONT SIZE=2>> > embedded EventsDescriptor may discard events, if the newly received </FONT>
<BR><FONT SIZE=2>> > or replacing Event Descriptor does not match the event.</FONT>
<BR><FONT SIZE=2>> ></FONT>
<BR><FONT SIZE=2>> > In the Megaco Secnarios, always just the good case is shown.</FONT>
<BR><FONT SIZE=2>> ></FONT>
<BR><FONT SIZE=2>> > e.g. a static interface with 4 logical incoming events ( </FONT>
<BR><FONT SIZE=2>> > S1,S2,S3,S4) would then set the EventsDescripror like:</FONT>
<BR><FONT SIZE=2>> ></FONT>
<BR><FONT SIZE=2>> > MGC guess the MG is in state i1, no Notify will be sent by MG, when </FONT>
<BR><FONT SIZE=2>> > state of interface is still i1.</FONT>
<BR><FONT SIZE=2>> ></FONT>
<BR><FONT SIZE=2>> > Events { </FONT>
<BR><FONT SIZE=2>> > S1{strict="exact"},S2{strict="state"},S3{strict="state"},S4{strict="</FONT>
<BR><FONT SIZE=2>> > state"} }</FONT>
<BR><FONT SIZE=2>> ></FONT>
<BR><FONT SIZE=2>> > ( Note: in case "state" is the default, then EventsDescriptor could </FONT>
<BR><FONT SIZE=2>> > be shorter)</FONT>
<BR><FONT SIZE=2>> ></FONT>
<BR><FONT SIZE=2>> > The events descriptor remains active, after Notification is sent. </FONT>
<BR><FONT SIZE=2>> > The strict parameter avoids unnecessary Notifications for the </FONT>
<BR><FONT SIZE=2>> > already by MGC known state.</FONT>
<BR><FONT SIZE=2>> ></FONT>
<BR><FONT SIZE=2>> > This mechanism would be very simple and avoids lost of any events, </FONT>
<BR><FONT SIZE=2>> > which is strong required for signalling interfaces on MG transferred </FONT>
<BR><FONT SIZE=2>> > via H.248 to an MGC.</FONT>
<BR><FONT SIZE=2>> ></FONT>
<BR><FONT SIZE=2>> ></FONT>
<BR><FONT SIZE=2>> > For a better illustration I have attached a Excel-File containing a </FONT>
<BR><FONT SIZE=2>> > simple scenario.</FONT>
<BR><FONT SIZE=2>> ></FONT>
<BR><FONT SIZE=2>> > So my question/proposal is:</FONT>
<BR><FONT SIZE=2>> ></FONT>
<BR><FONT SIZE=2>> > - Is it possible to extend the existing static state interfacepackages like H.248.26 with this</FONT>
<BR><FONT SIZE=2>> > strict feature?</FONT>
<BR><FONT SIZE=2>> > - If not, can I get this functionality otherwise ?</FONT>
<BR><FONT SIZE=2>> ></FONT>
<BR><FONT SIZE=2>> > Kind regards</FONT>
<BR><FONT SIZE=2>> ></FONT>
<BR><FONT SIZE=2>> > Thomas Voith</FONT>
<BR><FONT SIZE=2>> ></FONT>
<BR><FONT SIZE=2>> </FONT>
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</P>
<P><FONT SIZE=2>-- </FONT>
<BR><FONT SIZE=2>_______________________________________________________________</FONT>
<BR><FONT SIZE=2> _</FONT>
<BR><FONT SIZE=2> V | Thomas Voith </FONT>
<BR><FONT SIZE=2> +---------------+ | Dept. VS/EAC2 [Systems] </FONT>
<BR><FONT SIZE=2> | A L C A T E L | | FL/2/50</FONT>
<BR><FONT SIZE=2> +---------------+ | </FONT>
<BR><FONT SIZE=2> | Tel: +49 711 821-40293</FONT>
<BR><FONT SIZE=2> | Alcanet: 259-40293</FONT>
<BR><FONT SIZE=2>Alcatel SEL AG | Fax: +49 711 821-40211</FONT>
<BR><FONT SIZE=2>Fixed Networks Division |</FONT>
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<BR><FONT SIZE=2>_______________________________________________________________</FONT>
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