Re: [MMUSIC] UPDATE mechanism for Trickle ICE - Comment on draft-ivov-mmusic-trickle-ice-sip-01

["Parthasarathi R" <[e-mail]>]

Emil,

In case of ICE Trickle handling in SIP (based on RFC 3261), glare is
unavoidable as per RFC 3264 offer/answer mechanism. The glare handling has
to be done by SIP provided mechanism like 491 handling in UPDATE/RE-INVITE.
draft-partha-rtcweb-jsep-sip-01 callflow works for UPDATE & ICE compliant
SIP UA and no need of extra extension.

INFO based mechanism fails to identify the actual glare situation in
offer/answer.

Of course,  it is possible to reduce the trickle ICE glare handling with
special SDP handling (enhanced offer/answer) within RE-INVITE/UPDATE in case
both endpoints supports the mechanism. 

Please read inline for more comments.

Thanks
Partha

 

> -----Original Message-----
> From: Emil Ivov [mailto:[e-mail]]
> Sent: Tuesday, October 22, 2013 6:39 AM
> To: Parthasarathi R
> Cc: Christer Holmberg; Enrico Marocco (TiLab); mmusic
> Subject: Re: UPDATE mechanism for Trickle ICE - Comment on draft-ivov-
> mmusic-trickle-ice-sip-01
> 
> On Mon, Oct 21, 2013 at 8:29 PM, Parthasarathi R
> <[e-mail]> wrote:
> > Hi all,
> >
> > I have mailed earlier why SIP INFO is not the right choice for
> Trickle ICE
> > in
> > http://www.ietf.org/mail-archive/web/mmusic/current/msg11964.html.
> 
> I remember. Have you noticed my answer?
> 
> http://www.ietf.org/mail-archive/web/mmusic/current/msg11932.html
> 

<Partha> Please note that my question is after your answer (msg11964 >
msg11932). </Partha>

> > The main
> > reason is the glare handling. I have added the callflow in Sec 6.4 of
> > draft-partha-rtcweb-jsep-sip-01 to explain how UPDATE handling will
> look for
> > Trickle ICE handling in SIP w.r.t JSEP mapping.
> 
> I am confused. You say that your main issue is glare handling and yet
> your draft proposes a solution that *introduces* glare (through
> crossing UPDATEs) and then doesn't say anything about handling it. Is
> this intentional? Am I missing something?
> 

<Partha> 491 is the only known glare handling. We shall work and further
enhance glare handling in UPDATE/RE-INVITE as it is obvious glare situation.
I wish to confirm that INFO mechanism does not work for this situation
before deep diving. </Partha>

> > Could you please explain how
> > glare with Trickle ICE Info package will be handled.
> 
> That's simple. Glare does NOT occur when trickling through INFO.

<Partha> The actual glare situation will be missed in INFO </Partha>

> 
> Emil
> 
> --
> https://jitsi.org