[MEDIACTRL] Control Framework SDP Review - Issue 1

[Chris Boulton <chris at ns-technologies.com>]

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