Subject: MMusic San Jose meeting

From: [email-masked] (Eve Schooler)
Date: Tue, 3 Jan 1995 13:08:40 -0800

Hi all,

We'd like to wholeheartedly thank both Ruth Lang and Thane Frivold of SRI 
for their extraordinary efforts organizing the MMusic session at the
San Jose IETF.  In addition, many thanks to the many presenters and
participants.  The minutes from the WG meeting are enclosed below,
and include pointers to on-line materials.

Eve and Abel

~~~~~~~~~~~~

      Multiparty Multimedia Session Control WG (MMusic)
                Minutes from the 31st IETF
                    San Jose, California
                     December 7, 1994

		    Meeting Organizers
	   Ruth Lang, [email-masked]
	   Thane Frivold, [email-masked]

			Chairs
	   Eve Schooler, [email-masked]
           Abel Weinrib, [email-masked]

These notes were prepared by Thane Frivold and Ruth Lang.  An on-line
copy of the minutes and the accompanying PostScript slides are
available from ftp://ftp.isi.edu/confctrl/minutes or
ftp://ws11.std.sri.com/confctrl/minutes in the files ietf.12.94 and
slides.12.94.tar.

The Multiparty Multimedia Session Control Working Group (MMUSIC) held
a single two hour session at the IETF meeting in San Jose,
California. The meeting was organized and led by Ruth Lang and Thane
Frivold due to the limited availability of the chairs, Abel Weinrib
and Eve Schooler because of employment changes. During the session,
Abel raised the possibility that the working group consider concluding
or refocusing, especially if the leadership of the group were to
change.

In an effort to make the working group aware of other standardization
efforts, two brief presentations were given on ITU teleconferencing
efforts by Ken Krechmer and Joerg Ott.  Ted Ko gave an overview of
both a centralized and a distributed implementation of the
Shenker-Weinrib-Schooler agreement protocol -- the implementation
experience gave rise to several interesting research issues concerning
generality, dynamicity, and scalability.  A summary of the responses
from a survey of existing session control protocols was given by Thane
Frivold, focusing on functional requirements for both session control
protocols and session descriptions.  Carsten Bormann presented an
overview of inter-system (horizontal) and intra-system (vertical)
session control requirements which left open questions on the
transport and semantic requirements. A presentation was given by Mark
Handley which identified additional requirements for the "sd" protocol
and a discussion of proposed extensions followed. The current goals
and milestones were reviewed by Ruth Lang and a list of potential
working group documents was discussed.

ITU-T Teleconferencing Overview (slides.12.94.a and slides.12.94.b)

Ken Krechmer, Technical Editor for Communications Standards Review,
spoke briefly about the scope and goals of the ITU, and, in
particular, about the ITU's three study groups looking at audio,
video, and data teleconferencing issues and standardization. Ken also
identified associated US Technical Advisory Groups (TAG) which provide
input to the ITU.

Joerg Ott gave a technical overview of the T.120 group, the ITU group
whose work most closely resembles the MMUSIC charter.  In particular,
Joerg outlined the features of the Multipoint Communication Service
(MCS) and the Generic Conference Control (GCC).  MCS provides group
transmission services atop a connection tree of TCP-like connections.
GCC, which is built atop of MCS, provides multiparty session
management. Like the MMUSIC architecture, GCC also makes the
distinction between "horizontal" (conference state exchange) and
"vertical" (media agent control) session control paths. These
recommendations are still under development but are targeted for draft
release in March 1995.

Teleconferencing Session Management Engine (slides.12.94.c)

Abel Weinrib presented an overview of the agreement protocol described
in "Managing Shared Ephemeral Teleconferencing State: Policy and
Mechanism" by Scott Shenker, Abel Weinrib, and Eve Schooler
(ftp://ftp.isi.edu:confctrl/docs/agree.ps).  While teleconferencing
has both policy and mechanism choices, a key to this algorithm is the
separation between resolution policy and system specific decision
mechanisms.  Ted Ko then spoke about his master's thesis work on the
implementation of this protocol.

The core of his implementation is a generalized "session engine" that
is to be used as a service by domain specific session managers. It is
not hard-wried to understand media specific or session specific
details, but rather, manipulates session control aspects expressed by
variables, members, rules, and consistency designators. He described a
session description language that he developed in order to
characterize the state his "session engine" acts upon.  Ted's initial
implementation used a centralized model (one session manager for
multiple applications) and he showed how it could be integrated into
Bellcore's Touring Machine.  The development of a distributed
implementation is complete but requires more thorough testing.

The implementation experience gave rise to several interesting
research issues concerning generality, dynamicity, and scalability. In
considering the generality required to support differing session
management systems, questions of end-system heterogeneity, differing
call models, and session policies arose. More study is required to
determine the appropriate balance between developing an
all-encompassing session engine and the associated cost of such a
heavy-weight implementation.

Source code for the session engine is available by contacting
[email-masked] ([email-masked] after January 15).

Session Control Protocol Survey Report (slides.12.94.d)

In advance of the meeting, a survey of existing session control
protocols was distributed on November 11 by Thane Frivold and Ruth
Lang. Seven responses were received before this meeting on the
following efforts:

   - AVCCP -- Kevin Lew, Janey Hoe (MIT)
   - CCCP -- Mark Handley, Ian Wakeman et al (UCL)
   - EXPANSE -- Howard Bussey, Steven Minzer (Bellcore)
   - GCC -- Joerg Ott, Carsten Bormann (from knowledge of ITU efforts)
   - SRI -- Ruth Lang, Thane Frivold (SRI)
   - Telescope -- Joerg Ott (Tech U. of Berlin), Carsten Bormann (U. of Bremen)
   - Touring Machine -- R. C. Sekar, Brian Coan (Bellcore)

Thane described the goals of the survey which were to encourage
documentation of existing session control protocols and subsequently
use this information in developing a basis for session control
protocol and session description functional requirements. He
identified points of commonality among the systems described despite
the variety of approaches to session management. He also summarized
specific functional requirements gleaned from the responses with
respect to both session control protocols and session descriptions.

Service Interoperability (slides.12.94.e)

Carsten Bormann described conference services as consisting of
communication and cooperation services. He then gave an overview of
session control requirements focusing on both inter-system
(horizontal) and intra-system (vertical) coordination. The horizontal
protocol is used for propagating global state information (e.g.,
membership, policy, encoding formats, and applications). The vertical
protocol implements local decisions (e.g., on local resource usage and
device management) based on global state and presents this conference
state to applications.  Carsten also noted that the horizontal session
protocol (in conjunction with the local vertical protocols) could be
used to transport (some) horizontal application protocols.  Although
somewhat outside the scope of session control per se, the transport
state maintained by the session control association could be used for
low-volume application interaction.  He wrapped up by posing open
questions focusing on whether the transport and semantic requirements
for the horizontal and vertical protocols share the same requirements
and can be satisfied by the same protocol and implementation.

Session Advertisement (slides.12.94.f)

Mark Handley gave an overview of the current sd packet payload
format. Based on experience gained through implementing a clone of
sd, he identified additional requirements for the sd session
description and described proposed extensions to address them. In
particular, he identified the need for extended contact information
(beyond owner of the conference), expected bandwidth consumption,
scheduling information for repeated events, and information required
for PIM. Van Jacobson pointed out that information content is distinct
from the distribution mechanism; other discussion focused on the
utility of including RP for PIM.

Working Group Goals and Milestones Review (slides.12.94.d)

Although the working group has produced an agreement protocol document
and an implementation of the agreement protocol engine, many of the
milestones in the original charter have passed.  As a result, Ruth
Lang presented a list of potential documents that might be appropriate
output for the working group. Suggestions included producing session
control protocol and session description functional requirement
documents (as separate documents from the protocol specification
itself), requirements and specification of the agreement protocol, and
a document on session control architecture. Interest was expressed by
Joerg Ott, Carsten Bormann, Eve Schooler, and Abel Weinrib in working
on an architecture document. Abel Weinrib and Ted Ko offered support
for producing needed documentation on the agreement protocol. Due to
time constraints, little additional discussion took place on scope and
direction of the working group. No action items were assigned as the
Transport Area Director and working group chairs must consult before
amending the charter.

Attendees:

Carsten Bormann        [email-masked]
Joerg Ott              [email-masked]
Frank Kastenholz       [email-masked]
Abel Weinrib           [email-masked]
Eve Schooler           [email-masked]
John Wroclawski        [email-masked]
Steve Casner           [email-masked]
Ruth Lang              [email-masked]
Charley Kline          [email-masked]
David Aschkensasy      [email-masked]
Ted Brunner            [email-masked]
Sally Floyd            [email-masked]
Nachum Shacham         [email-masked]
Steve Richardson       [email-masked]
Rosen Sharma           [email-masked]
Hideki Sunahara        [email-masked]
Scott Williamson       [email-masked]
Mark Prior             [email-masked]
Julio Escobar          [email-masked]
Eric Fleischman        [email-masked]
Pierre Lin             [email-masked]
Derya Cansever         [email-masked]
Lud-Jen Chiang         [email-masked]
Bill Babson            [email-masked]
Claire Griffin         [email-masked]
Jim Dorcey             [email-masked]
John Lynn              [email-masked]
Tom Bowers             [email-masked]
Mitra                  [email-masked]
Steve Justus           [email-masked]
David Kaufman          [email-masked]
Kathy Huber            [email-masked]
Stephen Ostrowski      [email-masked]
Phil Irey              [email-masked]
Joseph Pang            [email-masked]
George Kajos           [email-masked]
Jason Yao              [email-masked]
Mark Amari             [email-masked]
Susuamu Matsui         [email-masked]
Bill Fenner            [email-masked] navy.mil
Allison Mankin         [email-masked]
Mark Handley           [email-masked]
Ken Krechmer           [email-masked]
Thane Frivold          [email-masked]
Don Merritt            [email-masked]
Naohiro Schichijo      [email-masked]
Gerry Meyer            [email-masked]
Ed Ellesson            [email-masked]
Alon Kleinmum          [email-masked]
Yoshikumi Maeyama      [email-masked]
Suresh Bhogavilli      [email-masked]
Katsuhiro Selayashi    [email-masked]
Dave Monachello        [email-masked]
Edward Lewis           [email-masked]
Ann Demirtjis          [email-masked]
Anders Klemets         [email-masked]
Shawn Gillam           [email-masked]

---

From: Ruth Lang <[email-masked]>
Date: Wed, 04 Jan 1995 08:43:18 -0800

Folks,

Please note that the error pointed out in the message below has been corrected
in the minutes file (ietf.12.94) at both ISI and SRI.  I will request that the
error be corrected in the IETF online minutes as well.

Ruth

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>From [email-masked] Tue Jan  3 17:16:10 1995
From: [email-masked] (Wieland Holfelder)
Subject: Re: MMusic San Jose meeting
To: [email-masked] (Eve Schooler)
Date: Tue, 3 Jan 1995 17:15:33 -0800 (PST)
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> ftp://ws11.std.sri.com/confctrl/minutes in the files ietf.12.94 and

Oops, if this is a URL, I guess it should rather be:
ftp://ws11.std.sri.com/pub/confctrl/minutes
                       ^^^
Thanks though,
-- Wieland
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Wieland Holfelder
International Computer Science Institute	Email: [email-masked]
1947 Center Street Suite 600			Fax  : +1-510-642-6865
Berkeley, CA 94704-1198				Phone: +1-510-642-4274 Ext. 302
					 URL: http://www.icsi.berkeley.edu/~whd
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