Pete,
I didn't say that what you propose _couldn't_ be done, only that the Recommendation does not currently sanction this. We could add it as a requirement to v4, but this would break backwards compatibility because pre-v4 EPs would of course not know to process these fields. I suppose all EPs could henceforth contain pre-v4 and v4 behavior, e.g., whether to tunnel in optional messages, and just use one or the other based on the version of the remote EP. Talk about "ugly," though...
Paul Long ipDialog
-----Original Message----- From: Pete Cordell [mailto:pete@TECH-KNOW-WARE.COM] Sent: Wednesday, November 08, 2000 4:54 AM To: ITU-SG16@MAILBAG.INTEL.COM Subject: Re: fastStart element in all Q.931 messages up toandincludingConnect
Not really. The various Q.931 messages still remain optional because tunnelling is optional. However, we can state that IFF you support tunnelling, THEN you must extract the tunnelling information even from those messages that you choose not to otherwise process. This breaks nothing that is said elsewhere in the standard. So the programmatic logic is something like:
switch( Q931 message type - octet 4 ish of message ) {
case SETUP: process setup; break;
case CONNCET: process connect; break;
case others: process ...; break;
default: // Not interested in these messages but must extract and handle // tunnelled stuff because I have decided to support tunnelling Find_UUIE(); Extract_ASN1(); Decode_ASN1(); Process_tunnelled_H245_and_H450_etc(); }
Its also less demanding on EPs than mandating that they must process all the various messages. After all, the vast majority of EPs couldn't care less that a PROGRESS messages has been sent. So why should they have to delve into them in detail if they are not interested in their meaning and content? We should achieve what we want with the minimum of work load on the various software entities, and this is simpler than mandating understanding of the other messages without losing any of the desired functionality.
Pete.
============================================= Pete Cordell Tech-Know-Ware pete@tech-know-ware.com +44 1473 635863 =============================================
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