Hi, Paul,

To get some information of one Q.931 message, say the "sourceInfo" of the "SETUP" message, what's the path starting from "TCP data" should we follow?

The path: "TCP data --> H323-UserInformation --> h323-uu-pdu --> h323-message-body --> setup --> sourceInfo " certainly is not right, as Q931 messages all have three outer mandatory fields: "Protocol discriminator", "CallReference" and "MessageType". The "H323-UserInformatin" is only part of "User-User" field, which in turn is in the same rank with "Protocol discriminator", "CallReference" and "MessageType" fields.

There should be a divergence point where all the Q.931 messages received from TCP are processed. Could you please consider this and tell me the right path?

Thanks, -Delphi ----- Original Message ----- From: Paul Long To: ITU-SG16@MAILBAG.INTEL.COM Sent: Tuesday, May 08, 2001 11:43 PM Subject: Re: How to get the heel of RAS Message.

Delphi,

1. I have no idea what the user-data component is used for. 2. I don't know what you mean by "get and set," but RAS does not use Q.931 or UUIEs in its encoding. It uses ASN.1 PER exclusively. I assume by your other question that you are asking what the outer-most encoding is for RAS. With call-signaling, it's Q.931; with RAS, it's ASN.1 PER--RAS uses ASN.1 PER throughout.

Paul Long ipDialog, Inc. -----Original Message----- From: Mailing list for parties associated with ITU-T Study Group 16 [mailto:ITU-SG16@mailbag.cps.INTEL.COM]On Behalf Of Delphi Sent: Tuesday, May 08, 2001 1:53 AM To: ITU-SG16@mailbag.cps.INTEL.COM Subject: How to get the heel of RAS Message.

Hi, all:

I have two problems concerning H.323 ASN.1.

1> H.323 ASN.1 states as follows: >>>>>>>>> H323-UserInformation::=SEQUENCE { h323-uu-pdu H323-UU-PDU, user-data SEQUENCE { protocol-discriminator INTEGER (0..255), user-information OCTET STRING (SIZE(1..131)), ..... }OPTIONAL, .... } <<<<<<<<<< My question is," What's the use of "user-date" field and what its protocol-discriminator field stand for? " Can anyone present me an example?

2> The H.323 ASN.1 tells us that following the path "H323-UserInformation>>h323-uu-pdu>>h323-message-body", we can get and set UUIE of Q931 messages. But how can we do the same thing with RAS messages? Or, what are the "ABSOLUTE PATH", the root, of the messages?

Thanks, -Delphi