Subject: RE: Possible new Real-Time Applications and Infrastucture (RAI)Area

From: "Yaakov Stein" <[email-masked]>
Date: Mon, 19 Sep 2005 13:51:54 +0200

I think that setting up this new area is a great idea,
and shows that we are adapting the structure of the IETF
to the applications people now want to use on the Internet.

A few more detailed comments follow.
 
>The Real-Time Applications and Infrastructure Area develops protocols 
>and architectures for delay-sensitive interpersonal communications.

Delay sensitivity impacts communications in several ways.

For setup protocols you want to minimize the number of
round-trips until the user has positive feedback of connectivity status.

For voice and interactive video, delay sensitivity rules out
retransmissions,
and so raises the issue of packet loss concealment.

This in general involves DSP and/or image processing treatments.
For more general data, this means forward error correction
and maximum likelihood estimation of missing data.

These mathematically sophisticated subjects have previously been avoided
in the IETF
(and are awfully hard to present in ASCII ID format).

Is it now proposed to treat these subjects in the IETF, 
and to attempt to draw in audiences interested in so doing?

> >Work in this area serves an emerging industry whose applications and 
> >services include voice and video over IP, instant messaging and 
> >presence. These applications and services are "real-time" in the
sense 
> >that delay impedes human participation in the associated systems.

This is a good characterization of the delay sensitivity problem,
but an unusual definition of "real-time".
Perhaps DSI (delay-sensitive infrastructure) or ISI (Interactive
Services Infrastructure)
more aptly captures the intent.

>The RAI Area is seeded with existing working groups from the Transport 
>and Applications Area: SIP, SIPPING, XCON, SIMPLE, GEOPRIV, ECRIT, 
>ENUM, IPTEL, MEGACO, MMUSIC, IEPREP, SPEECHSC, and SIGTRAN.  

I don't really see how GEOPRIV and ECRIT fit in,
based on the delay sensitivity criterion, although they may 
somewhat satisfy the rule of thumb.

My real question is whether the rule of thumb was invented
in order to aid the "seeding" and thus more equitably divide
WGs among areas.

Y(J)S

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From: Harald Tveit Alvestrand <[email-masked]>
Date: Mon, 19 Sep 2005 22:23:56 +0200

> somewhat satisfy the rule of thumb.

Good to see more comment on this topic! (which is one I like)

I think all areas in the IETF are more-or-less defined as "core of the 
area" + "what is closely linked to the core" + "what fits less badly there 
than elsewhere" - ECRIT would come under "closely linked", since its 
subject area is use of the SIP-type services; GEOPRIV might be more 
characteristic of "fits less badly here than elsewhere" - it is used by 
many of the services like ECRIT, but is also used (or should be) by WGs in 
other areas.

                     Harald

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From: Melinda Shore <[email-masked]>
Date: Mon, 19 Sep 2005 16:35:58 -0400

> many of the services like ECRIT, but is also used (or should be) by WGs in

I think there may be a problem here in that "real time" may
suggest to a number of people a level of rigor in timing that's
really not applicable to much of the work the new area is
intended to cover.  I'm enthusiastic about the area;
not so crazy about its name.

Melinda

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From: "Marshall Eubanks" <[email-masked]>
Date: Mon, 19 Sep 2005 17:05:14 -0400

On Mon, 19 Sep 2005 16:35:58 -0400
> really not applicable to much of the work the new area is

It seems that on the Internet so called real time applications are
generally either

delay sensitive 

and / or 

Jitter intolerant. (Which  are, of course, different things.)

I guess I would go for "Low Latency Applications and Infrastucture " (LLAI) myself.

Regards
Marshall Eubanks

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From: "James M. Polk" <[email-masked]>
Date: Mon, 19 Sep 2005 16:06:42 -0500

>intended to cover.  I'm enthusiastic about the area;

I am also enthusiastic about the area

>not so crazy about its name.

I am also concerned about the name. This is basically (not absolutely!) 
about what is in and around SIP, and not everything in SIP is in 
"real-time", with GEOPRIV being one of them. Yet, I believe GEOPRIV should 
be in this new area as there are many of the same faces in the ECRIT, 
GEOPRIV and SIP/SIPPING/SIMPLE WGs. This tells me there is a commonality 
between them such that they ought to be in the same area.

Perhaps something like "Rich Media Apps" Area, shortened to the "Media 
Area" in discussions.

>Melinda

cheers,
James

                                 *******************
                 Truth is not to be argued... it is to be presented.

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From: "JFC (Jefsey) Morfin" <[email-masked]>
Date: Tue, 20 Sep 2005 00:28:56 +0200

>I guess I would go for "Low Latency Applications and Infrastucture " 

Do you conceptually accept in that wording that an OPES can be 
plugged in there, for example as part of a service to the exchange? 
The WG-OPES has worked on HTTP, and now on SMTP. IMHO OPES also fit 
pseudo-synchronous exchanges. In that case the WG-OPES should be able 
to dialog with the new area at a later stage.
jfc

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From: Dave Crocker <[email-masked]>
Date: Wed, 21 Sep 2005 07:21:56 -0700

> Jitter intolerant. (Which  are, of course, different things.)

Marshall,

I think you are onto something quite fundamental.  In recent times, the IETF 
has gotten quite good at introducing delay and making foliks jittery, so it 
does make some sense to be official about it...

On a slightly more serious note, I'm struck by the co-occurrence of a focus on 
"delay sensitive" work with one on "delay tolerant" (DTN) work.  Methinks 
there really is some commonality on the core services, although the apps are 
wildly divergent.  Probably.

However, the skillsets involved in paying attention to infrastructure 
performance, as needed for internet and transport work, is fundamentally 
different from that needed for the services that use the infrastructure 
(generally called "applications" but why be fussy?)

It strikes me that the real danger of creating this specialized area will be a 
failure to produce results that integrate with the rest of the IETF work.

Why don't we have an email area that covers relevant infrastructure services, 
and a web area that also does, since each of these applications have different 
infrastructure requirements and the lack of focus on them has had a negative 
impact on both of their operations.

(And, yes, I'm serious that they have different service needs and that their 
operation is affected by this.)

d/
-- 

  Dave Crocker
  Brandenburg InternetWorking
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