How to get the heel of RAS Message.

[Delphi]

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 at 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 at mailbag.cps.INTEL.COM]On Behalf Of Delphi
    Sent: Tuesday, May 08, 2001 1:53 AM
    To: ITU-SG16 at 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
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