Subject: RE: [Megaco] what is the meaning of Reserve Value and Reserve Gro up

From: Raphael Tryster <[email-masked]>
Date: Tue, 19 Apr 2005 09:16:18 +0200

I understand that Tom's Case 1 below must use multiple SDP sessions, and
hence ReserveGroup, because different transport protocols are involved.  My
question is whether Case 2 could be rewritten as two SDP sessions, using
ReserveGroup instead of ReserveValue, as follows:

Case 2:

Local={
v=0
o=...
s=...
c=ATM ...
m=audio ? AAL1/ATMF 96
a=atmmap: 96 AMR
v=0
o=...
s=...
c=ATM ...
m=audio ? AAL1/ATMF 97
 a=atmmap: 97 PCMU
etc.
}

ReserveGroup=true would cause resources to be reserved to support both AMR
and PCM mu-law over AAL1.  ReserveGroup=false would cause resources to be
reserved for just one of these possibilities, with AMR preferred.

Is the above equivalent in functionality to Case 2 as Tom wrote it 3 years
ago?  If so, what additional considerations would influence which format to
prefer?

Raphael Tryster

-----Original Message-----
From: Tom-PT Taylor [mailto:[email-masked]]
Sent: Saturday, March 16, 2002 12:48 AM
To: 'Zhang, Yuyong'; 'Christian Groves'; John Joseph Chooracken
Cc: [email-masked]'
Subject: RE: [Megaco] what is the meaning of Reserve Value and Reserve Gro
up

A group is equivalent to a session description (i.e. the v=0 line and what
follows).  So ReserveGroup indicates whether to choose and reserve resources
for one of a set of session descriptions, or to reserve resources for all of
them.  Within each, ReserveValue indicates whether to choose and reserve one
of a set of alternative values (particularly codecs) or to be prepared to
handle all of the presented values.  Christian's examples below translate
into

Case 1:

Local={
v=0
o=...
s=...
c=IP IP4 ...
m=audio ? rtp/avp 96
a=rtpmap: 96 AMR
[see draft-ietf-avt-rtp-amr-13.txt]
v=0
o=...
s=...
c=ATM ...
m=audio ? AAL1/ATMF 0
[see RFC 3108]
etc.
}

ReserveGroup=true would cause resources to be reserved for both AMR over IP
and PCM mu-law over AAL1.  ReserveGroup=false would cause the MG to choose
one of these two possibilities, with the first being preferred.

Case 2:

Local={
v=0
o=...
s=...
c=ATM ...
m=audio ? AAL1/ATMF 96 97
a=atmmap: 96 AMR
a=atmmap: 97 PCMU
[references as above]
etc.
}

ReserveValue=true would cause resources to be reserved to support both AMR
and PCM mu-law over AAL1.  ReserveValue=false would cause resources to be
reserved for just one of these possibilities, with AMR preferred.

-----Original Message-----
From: Zhang, Yuyong [mailto:[email-masked]]
Sent: Friday, March 15, 2002 2:38 PM
To: 'Christian Groves'; John Joseph Chooracken
Cc: [email-masked]'
Subject: RE: [Megaco] what is the meaning of Reserve Value and Reserve
Gro up

Hi Christian, all

How the Group information are represented in the SDP? Please give a example
in SDP syntax about the usage of Group (the c-line, m-line, a-line
combination.

Regards,

Yuyong

-----Original Message-----
From: Christian Groves [mailto:[email-masked]]
Sent: Tuesday, March 12, 2002 4:22 PM
To: John Joseph Chooracken
Cc: [email-masked]'
Subject: Re: [Megaco] what is the meaning of Reserve Value and Reserve
Group

Hello John,

Reserve Group allows you to reserve resources for different sets of a
number of properties/SDP lines. eg.
Group ID 1
        pkg1/codec = AMR
        pkg2/transport = IP
Group ID 2
        pkg1/codec = G711
        pkg2/transport = ATM

Whereas reserve value only reserves values for single properties. eg.
        pkg1/codec = AMR, G711
        pkg2/transport = ATM

Regards, Christian

John Joseph Chooracken wrote:
>
> Hi ,
>
>    Please tell me  what is the difference between Reserve Value and
Reserve
> Group in Local Control Descriptor.
>
> Thanx in advance.
>
> Regards,
> John
> "Scientists study the world as it is, engineers create the world that
never
> has been. "
> -- Theodore Von Karman
>
> _______________________________________________
> Megaco mailing list
> [email-masked]
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