Subject: Re: [Slim] Comments on proposed SLIM charter

From: Randall Gellens <[email-masked]>
Date: Mon, 16 Mar 2015 10:12:33 -0700

At 4:57 PM -0400 3/13/15, Henning G Schulzrinne wrote:

>  And, for the record, I continue to disagree with the current choice 
> of discarding a 3840-like (not necessarily the protocol itself) 
> approach. I consider this a call routing problem which is not 
> appropriate for an SDP solution, just by standard SIP architectural 
> layering.

There has been significant work over the years on trying to resolve 
the SDP vs SIP issue.  First as a small and very informal group prior 
to and following the Orlando IETF.  The conclusion there was that SDP 
made more sense for the emergency calling case, so the work 
progressed along that route.  Then, in Berlin, Henning made his case 
that SDP was the wrong choice, and Gunner volunteered to see if the 
SIP-only approach could work.  We went through email discussions 
(before there was a list, but Henning and the other SIP-only 
proponents were in the distribution list but did not actively 
participate) and worked through the cases.  I published revisions of 
the draft showing both as candidate solutions.  Finally, as the draft 
tries to make clear, we eventually reached the conclusion that 
neither approach is ideal, both have benefits and problems, but 
either could be made to work.  There are reasons why the SDP approach 
makes more sense, especially for the emergency services case, and the 
SIP case has a few more problems, but fundamentally, this more a 
stylistic/preference/religion debate than just technical aspects. 
We've spent much time and effort trying to make the best technical 
evaluation, and I believe we are moving forward on that basis.  I 
therefore don't have much patience for reopening the debate a third 
time, especially when it comes down to personal preference and not 
technical problems.  If we are going to ever get anything completed 
that can be implemented and deployed, we need to move forward.

Therefore, I suggest that unless anyone can point to reasons why the 
SDP approach will not work, we should accept the conclusion and move 
forward.

>  On Fri, Mar 13, 2015 at 4:30 PM, Ben Campbell 
> <<mailto:[email-masked]>[email-masked]> wrote:
>
>  Hi,
>
>  For the record, I support this work. But I have some concerns about 
> the proposed charter at 
> <https://datatracker.ietf.org/doc/charter-ietf-slim>https://datatracker.ietf.org/doc/charter-ietf-slim 
> . Apologies if this rehashes old discussions; I have only recently 
> joined the mailing list (I did scan the archive, but likely missed 
> things.)
>
>  I don't find the charter text motivating the linkage between the 
> mail problem and the real-time problem very convincing. I'm not 
> saying it's wrong; just that it hasn't convinced me.
>
>  The text suggests a single work group to reinforce commonality in 
> the solutions. That seems backwards to me; I'd like to see more on 
> why people think the problems benefit from a common solution. Do 
> you think there will be mechanism in common, beyond the use of 
> language tags? Do you see a common implementor community? A common 
> protocol development community?
>
>  I'd like to see something about why people don't think the 
> real-time problem is at least partially solved by RFCs 3840 and 
> 3841. If that's a forgone conclusion, the charter needs to clearly 
> motivate it. The draft is slightly more helpful here in mentioning 
> that 3840/3841 were considered but discarded, but that's not 
> obvious from the proposed charter text.
>
>  Part of this may be that I am not sure if this is looking at a 
> call-routing problem (i.e. getting the call to an appropriate 
> destination for a language) and/or a language negotiation problem 
> (i.e. deciding what language you are going to use once the call is 
> established. The first is mentioned, although the text about 
> invoking translators, etc, might also imply the second. The charter 
> should clearly describe the problem.
>
>  If the idea is to finish the existing drafts, the charter should 
> say that. Even so,
>  the schedule seems optimistic, unless you expect those drafts to go 
> to WGLC right after
>  the charter is approved.
>
>  I find paragraph 2 a bit hard to follow--it seems to be a single 
> complex sentence.
>
>  Thanks!
>
>  Ben.
>
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-- 
Randall Gellens
Opinions are personal;    facts are suspect;    I speak for myself only
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plants and animals.  When exposed to light they undergo photosynthesis;
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don't we all?