Re: [AVT] draft-ietf-avt-hdrext-12

[Michael A Dolan <md.1 at newtbt.com>]

Magnus-

We all agree the preferable choice is option (a), but how do we get 
there?  The management of the RTP header extensions is not ideal due 
to circumstances now behind us.  I don't see how we can make existing 
conformant practice (nearly anything) non-conformant upon publication 
of this ID.  At best, all a STDs track publication can say is 
"SHOULD" at this point in my personal view.  It is not likely to be 
as simple as managing the "defined by profile" field as an enumerated 
field by IANA or explicit RFC publication as some have suggested, 
since 3350 gave no indication at all how to manage this field or even 
if it was a constant (which some presume incorrectly).

IETF AVT WG is an open process. All other existing current extension 
syntax authors are invited to try and make the effort to merge them 
into a single compatible standard design as part of the 
process.  Although I wish I was aware of this other design sooner in 
the process, I tried to craft the proposal in this thread so that 
both could exist concurrently in a well-structured manner.  I would 
welcome other uses to come forward so we could craft a single overall 
mechanism.  We all *know* there are other uses (I found a new one 
last week), but the burden is on those authors to come forward and 
make the effort. Lacking other contributions, the WG should make an 
effort to make the published ones (minimally these two) work as best we can.

I am still trying to avoid an evaluation ("bake-off") of the two 
designs since it will alienate one of them after the fact, but....you 
cite "tradeoff" and "proprietary" evaluation criteria to support the 
4/4-bit design alone in pursuit of option (a).  So if the path 
forward is to have a technical evaluation of tradeoffs and relative 
"propriety" to reach option (a), then I would like to understand your 
conclusions better, especially the one about one being more 
proprietary than another.

But before we enter into a "bake-off", it is still my view that the 
best we can accomplish under the circumstances of how 3350 left 
things is to document what practices we know about (via authors 
willing to bring them forward) in a clearly discriminating manner, 
concurrent with a recommendation for all new designs.  Please note 
that I did not try to assert that the other design in this thread as 
the preferred one - the contrary in fact, deferring to the existing 
ID's proposal for future designs.

Regards,

        Mike

At 12:03 PM 7/26/2007, Magnus Westerlund wrote:
> Michael A Dolan skrev:
> > Dave and all-
> > I was hoping to avoid a debate on relative deployment and the value 
> > of 4 bits versus 8 bits by proposing option (c) below (which is 
> > what I tried to articulate in last week's post).  In a perfect 
> > world, we would drive to (a), but I don't see how to get there in 
> > any reasonable timeline.
> > Mean-time the world moves on making more of these deployments, and 
> > worse, more non-conformant variants we don't even know about....
> > Can everyone live with option (c)?
>
> Preferably no, this is a core extension that we are likely to see 
> quite a lot of use in the future. I think 4+4 has a good tradeoff. I 
> would like to go with a) because of this to avoid confusing things. 
> If there are "proprieatery" deployment as it is of 8+8 that is not 
> different from other "proprieatery" extensions in this field.
>
> > > Choices:
> > >
> > > a) go with just 4+4 or just 8+8, and drop one.  I am aware of 
> > > implementations of both, so this isn't ideal.
> > >
> > > b) in the same document, require support for both.
> > >
> > > c) in the same document, require support for one, and recommend 
> > > support for the other.
> > >
> > > d) publish one separately, as an informational RFC.
>
> Cheers
>
> Magnus Westerlund
>
> IETF Transport Area Director & TSVWG Chair
> ----------------------------------------------------------------------
> Multimedia Technologies, Ericsson Research EAB/TVM/M
> ----------------------------------------------------------------------
> Ericsson AB                | Phone +46 8 4048287
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