Re: [siprec] Can an MS object span several CSs in a CSG?

["Elwell, John" <[e-mail]>]

 

> -----Original Message-----
> From: Parthasarathi R (partr) [mailto:[e-mail]] 
> Sent: 25 May 2011 08:48
> To: Elwell, John; Charles Eckel (eckelcu); Ram Mohan R 
> (rmohanr); [e-mail]
> Subject: RE: [siprec] Can an MS object span several CSs in a CSG?
> 
> John,
> 
> ===================================================================
> > 3) B transfer the call of A & B to C using REFER, B2BUA 
> converts REFER
> 
> > to RE-INVITE towards A & C and A & C are connected. B2BUA 
> updates RS 
> > with CS2, Participant1 as A & participant2 as C, MS1(A's media 
> > stream), MS2(C's media stream). There is no update on RS1, 
> CSG1, MS1, 
> > MS2. MS2 will become MS2 with the new association and in terms of 
> > format, it will associate with <send> tag
> [JRE] What harm is done (what do we lose) if, following transfer, A's
> media stream is called MS3 and C's media stream is called MS4? 
> =====================================================================
> <Partha> To indicate MS1 as MS3, MS1 media block has to be stopped in
> the partial-update and start MS3 separate which is not 
> required in case
> there is a means to have common MS1. </Partha>
[JRE] It seems this distorts the model in order to give some minor efficiency improvement during metadata updates. I doubt that this alone is sufficient justification for having the MS persist from one CS to another CS.

> 
> ==============================================================
> ==========
> =======================
> MS3 can reference the same SDP m-line (through a=label) as MS1, and
> likewise MS4 could reference the same SDP m-line as MS2, if we are
> concerned about recycling media descriptions in RS SDP.
> ==============================================================
> ==========
> ==================
> <Partha> As you mentioned, we will lose recycling of media description
> in RS SDP without common value in media stream object for 
> this scenario.
[JRE] I don't understand your point. With my proposal we can still recycle RS SDP m-lines.

> AFAIK, Your proposal needs enhancement in RFC 4574 as label attribute
> scope is within single SIP message and not required to be 
> unique in all
> SIP messages of a given dialog. </Partha> 
[JRE] But I think we could nail that down as a requirement of the SIPREC protocol.

John (as individual)

> 
> Thanks
> Partha
> 
> John (as individual)
> 
> > 
> > Thanks
> > Partha  
> > 
> > -----Original Message-----
> > From: Charles Eckel (eckelcu) 
> > Sent: Wednesday, May 25, 2011 1:39 AM
> > To: Ram Mohan R (rmohanr); Parthasarathi R (partr); 'Elwell, John';
> > '[e-mail]'
> > Subject: RE: [siprec] Can an MS object span several CSs in a CSG?
> > 
> > Hi Ram,
> > 
> > I think that is many cases, they will be treated as separate 
> > MSs due to
> > the complexities you mention. However, I am trying to understand if
> > Partha feels allowing an SRC to treat them as a single MS is still
> > required. If not, then what is a use case? A concrete example 
> > would help
> > me, and potentially others, to better understand the 
> motivation behind
> > Partha's requirement for modeling media from multiple CSs 
> as a single
> > MS.
> > 
> > Cheers,
> > Charles
> > 
> > > -----Original Message-----
> > > From: Ram Mohan R (rmohanr)
> > > Sent: Tuesday, May 24, 2011 9:36 AM
> > > To: Charles Eckel (eckelcu); Parthasarathi R (partr); 
> Elwell, John; 
> > > [e-mail]
> > > Subject: RE: [siprec] Can an MS object span several CSs in a CSG?
> > > 
> > > Charles,
> > > 
> > > I did bring about this specific usecase of MMOH/MOH stream being 
> > > played to different participants earlier and suggested that 
> > they have 
> > > to treated as a same MS across multiple CSs (potentially recorded
> > using multiple RSs).
> > > Refer 
> > > http://www.ietf.org/mail-archive/web/siprec/current/msg01886.html
> > > 
> > > We had several discussions on it and it and several folks were in 
> > > favor of treating it as separate MS as there would be 
> > complexity in DB
> > design.
> > > 
> > > Regards,
> > > Ram
> > > 
> > > 
> > > > -----Original Message-----
> > > > From: [e-mail] 
> [mailto:[e-mail]] On 
> > > > Behalf Of Charles Eckel (eckelcu)
> > > > Sent: Tuesday, May 24, 2011 9:11 PM
> > > > To: Parthasarathi R (partr); Elwell, John; [e-mail]
> > > > Subject: Re: [siprec] Can an MS object span several CSs 
> in a CSG?
> > > >
> > > > Hi Partha,
> > > >
> > > > Is an example of this the same music on hold audio stream 
> > existing 
> > > > as the same MS within multiple CSs? If so, then I 
> understand your 
> > > > requirement to be that the SRC be able to indicate multiple 
> > > > instances of this audio stream within several CSs as 
> > being the same 
> > > > MS. Is that correct?
> > > >
> > > > Thanks,
> > > > Charles
> > > >
> > > > > -----Original Message-----
> > > > > From: [e-mail] 
> > [mailto:[e-mail]] On
> > > > Behalf Of Parthasarathi R (partr)
> > > > > Sent: Tuesday, May 24, 2011 4:26 AM
> > > > > To: Elwell, John; [e-mail]
> > > > > Subject: Re: [siprec] Can an MS object span several CSs 
> > in a CSG?
> > > > >
> > > > > John,
> > > > >
> > > > > I agree that it is not mandatory to consider recorded 
> > stream of a 
> > > > > specific participant in several CS within the same CSG as one
> > > > recorded
> > > > > stream but SIPREC protocol design MUST NOT restrict a 
> > SRC in case 
> > > > > it wishes to design in such a way.
> > > > >
> > > > > Thanks
> > > > > Partha
> > > > >
> > > > > -----Original Message-----
> > > > > From: [e-mail] 
> > [mailto:[e-mail]] On
> > > > Behalf
> > > > > Of Elwell, John
> > > > > Sent: Tuesday, May 24, 2011 1:06 PM
> > > > > To: [e-mail]
> > > > > Subject: [siprec] Can an MS object span several CSs in a CSG?
> > > > >
> > > > > We seem to have consensus that a Media Stream object 
> > represents a 
> > > > > recorded media stream, contributed to by one, several or all 
> > > > > Participants. However, Partha also wrote:
> > > > >
> > > > > "2) Each MS lifetime related to CSG because participant 
> > may move 
> > > > > from one CS to another CS within single CSG and also 
> > CSG will span
> > 
> > > > > across multiple RS."
> > > > >
> > > > > I am not sure we had resolved this during earlier 
> > discussions on 
> > > > > the scope of an MS object. Although the same Participant can 
> > > > > participate
> > > > in
> > > > > several CSs within the same CSG, I don't think the 
> > recorded media 
> > > > > streams need to be considered the same. Any other views?
> > > > >
> > > > > John (as individual)
> > > > > _______________________________________________
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