Subject: [MEDIACTRL] Control Framework SDP Review - Issue 1

From: Chris Boulton <[email-masked]>
Date: Fri, 02 Oct 2009 11:52:44 +0100

Jonathan Lennox has kindly provided expert SDP review for the Media Control Channel Framework document.  This is the first in a series of emails intended to address the points raised.  At this final stage your input is extremely important.

My first comment is on the use of the values "TCP/CFW", "TCP/TLS/CFW",
"SCTP/CFW" and "SCTP/TLS/CFW" for the SDP <proto> field, with a "fmt"
field of "*".  A more usual use of the proto field would be to use the
existing proto fields "TCP", "TCP/TLS", "SCTP", or "SCTP/DTLS", and then
(after defining "application/cfw" as a media type) use "cfw" as the
<fmt> field.

Thus, instead of having

m=application 7575 TCP/CFW *

you'd have

m=application 7575 TCP cfw

This has the advantage of leveraging other existing work in SDP, e.g.
you would get ICE-TCP "for free" once it's finished.

To be sure, there would be some disadvantages of this.

Notably, "SCTP" and "SCTP/DTLS" are still only defined in an individual
I-D, and there's been only limited attention paid to it in the MMUSIC
community.  On the other hand, if Mediactrl has the expertise to
understand how SCTP should work in a comedia context, it'd probably be
better to let this be available to everything that would want to use it,
rather than just CFW.

[Chris] I agreed that the proposed change is more elegant and if it means that we get ICE-TCP for free then its a bonus.  It is  the recommendation of the authors that this change is made to the draft.  Any comments or objections?

-- 
Chris Boulton
CTO & Co-founder
NS-Technologies <http://www.ns-technologies.com>
m: +44.7876.476681

---

From: "McGlashan, Scott" <[email-masked]>
Date: Fri, 2 Oct 2009 11:09:59 +0000

Seems a reasonable change to me. 

Scott

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf Of Chris Boulton
Sent: Friday, October 02, 2009 12:53
To: [email-masked]
Subject: [MEDIACTRL] Control Framework SDP Review - Issue 1

My first comment is on the use of the values "TCP/CFW", "TCP/TLS/CFW", "SCTP/CFW" and "SCTP/TLS/CFW" for the SDP <proto> field, with a "fmt"
field of "*".  A more usual use of the proto field would be to use the existing proto fields "TCP", "TCP/TLS", "SCTP", or "SCTP/DTLS", and then (after defining "application/cfw" as a media type) use "cfw" as the <fmt> field.

Thus, instead of having

you'd have

Notably, "SCTP" and "SCTP/DTLS" are still only defined in an individual I-D, and there's been only limited attention paid to it in the MMUSIC community.  On the other hand, if Mediactrl has the expertise to understand how SCTP should work in a comedia context, it'd probably be better to let this be available to everything that would want to use it, rather than just CFW.

--
Chris Boulton
CTO & Co-founder
NS-Technologies <http://www.ns-technologies.com>
m: +44.7876.476681
_______________________________________________
MEDIACTRL mailing list
[email-masked]
https://www.ietf.org/mailman/listinfo/mediactrl
Supplemental Web Site:
http://www.standardstrack.com/ietf/mediactrl

---

From: Lorenzo Miniero <[email-masked]>
Date: Fri, 2 Oct 2009 13:26:00 +0200

Ok for me as well, as it also removes the ambiguity we reported
in Minneapolis, the one related to the '*' as format in the negotiation
(which was clarified anyway).

L.

On Fri, 2 Oct 2009 11:09:59 +0000

-- 
Lorenzo Miniero <[email-masked]>

---

From: "Jonathan Lennox" <[email-masked]>
Date: Fri, 2 Oct 2009 11:01:34 -0400

Just to re-iterate one point in my original e-mail, though -- this would
mean that you'd either have to normatively depend on the SCTP-comedia
draft (which is still an individual submission), or drop SCTP support
from this draft.
	
-- 
Jonathan Lennox
Vidyo, Inc
[email-masked]

> From: [email-masked] [mailto:[email-masked]]
On
> Behalf Of Chris Boulton
> Sent: Friday, October 02, 2009 6:53 AM
> To: [email-masked]
> Jonathan Lennox has kindly provided expert SDP review for the Media
> Control Channel Framework document.  This is the first in a series of
> emails intended to address the points raised.  At this final stage
your
> input is extremely important.
> 
> 
> [Chris] I agreed that the proposed change is more elegant and if it
> means that we get ICE-TCP for free then its a bonus.  It is  the
> recommendation of the authors that this change is made to the draft.
> Any comments or objections?
> 
> --
> Chris Boulton
> CTO & Co-founder

---

From: Chris Boulton <[email-masked]>
Date: Mon, 05 Oct 2009 13:28:55 +0100

> draft (which is still an individual submission), or drop SCTP support
[Chris] I would recommend to the group that we drop SCTP support from 
the document.  Any objections?

---

From: Chris Boulton <[email-masked]>
Date: Mon, 19 Oct 2009 13:08:14 +0100

Media Controllers,

This remains (Issue 1) the last issue to be resolved before we submit 
the next version of the Media Control Channel Framework for (hopefully) 
the last time.  After a lot of consultation with SDP experts (thanks 
Jonathan and Gonzalo) I propose that the final change is made to the 
document.  This will involve:

- Use proposal suggested by Jonathan Lennox of formatting the 'm' line 
of our SDP without having to define a new 'proto' field + using the 
'fmt' field to convey control framework support.  This would be achieved 
by defining a new MIME type to represent our format.

The change would result in the media line changing from:

to:

This also has the bonus of ICE support for free.

- removing SCTP support from the doc (as per previous mails) due to lack 
of progress in its definition.

I will be making the appropriate changes towards the end of this week in 
preparation for the document deadline.  If anyone has any objections to 
the changes its important that you raise them now.

Thanks,

Chris.