Subject: [Megaco] Audit Descriptor and under/overspecified Descriptor

From: [email-masked]
Date: Thu, 13 Feb 2003 14:36:18 +0530

Hi

I have a query with respect to conflicts between the underspecified/
overspecified
descriptor processing and audit descriptor processing. Both of these descriptors
in
a command request mandate the inclusion of descriptors in the command reply.
Whereas
there can be scenarios when multiple candidate descriptors can occur in the
command
reply. How is the contention resolved?

In case this has been discussed before, please give a pointer to the relevant
mails.

I am taking an example of media descriptor.

e.g.
Assuming an ephemeral termination with the following current state of the
descriptors:

LocalControl { Mode = Inactive, nt/jit=120 }
Local {
     v=0
     c=IN IP4 132.168.200.4
     m=audio 6000 RTP/AVP 4
}

Now, a MODIFY command with Audit descriptor and an underspecified/ overspecified
Media
Desc (Local desc) is received.

Modify = rtp1000 {
     Audit { Media },
     Media { Stream = 1 {
               LocalControl { Mode = ReceiveOnly, nt/jit=40 },
               Local {
                    v=0
                    c=IN IP4 $
                    m=audio $ RTP/AVP 0 8
}}}}

Assuming that during the MODIFY command processing, MG selects the following new
values:
IP address          -    132.168.200.5
port number         -    7000
payload type   -    8

How should the MODIFY command reply look like:

Option 1
Old media descriptor is sent.
Modify = rtp1000 {
     Media { Stream = 1 {
               LocalControl { Mode = Inactive, nt/jit=120 },
               Local {
                    v=0
                    c=IN IP4 132.168.200.4
                    m=audio 6000 RTP/AVP 4
}}}}
But, as per the protocol the underspecified/ overspecified Local descriptor
after resolution in the MG must be returned in the response.

Option 2
Old media descriptor with overwritten underspecified/ overspecified Local
descriptor after resolution is sent.
Modify = rtp1000 {
     Media { Stream = 1 {
               LocalControl { Mode = Inactive, nt/jit=120 },
               Local {
                    v=0
                    c=IN IP4 132.168.200.5
                    m=audio 7000 RTP/AVP 8
}}}}
But, the complete Media descriptor is inconsistent, i.e., Local COntrol is old
but
the Local descriptor is the new one. Although, MGC would know which descriptor
was
underspecified/ overspecfied in the request and can relate.

Option 3
New media descriptor is sent.
Modify = rtp1000 {
     Media { Stream = 1 {
               LocalControl { Mode = ReceiveOnly, nt/jit=40 },
               Local {
                    v=0
                    c=IN IP4 132.168.200.5
                    m=audio 7000 RTP/AVP 8
}}}}
But, as per the protocol the descriptors need to be processed in sequence of
occurance
and therefore, media descriptor should be the old one.

I am still unclear if the protocol resolves this problem.
Please comment?

Rgds

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