Subject: MMUSIC minutes + slides

From: [email-masked] (Eve Schooler)
Date: Thu, 9 Jan 97 09:55:47 PST

Multiparty Multimedia Session Control Working Group (MMUSIC)
                   Minutes from the 37th IETF
		  San Jose, California, USA
			December 9-10, 1996

                             Chairs
		    Mark Handley, [email-masked]
		    Ruth Lang, [email-masked]
		    Eve Schooler, [email-masked]

MMUSIC met during two sessions at the 37th IETF, both of which were
multicast.  A summary of each of the talks and pointers to
relevant Internet-Drafts or related documents is included below.  An
on-line copy of these minutes and accompanying slides are available 
from ftp://ftp.isi.edu/confctrl/minutes in the files ietf.12.96 and 
slides.12.96.{tar, tar.Z}.  Individual slide presentations can be obtained 
from the directory slides.12.96.  These notes were prepared by Ruth Lang.

Mark Handley (USC/Information Sciences Institute) described the significant 
modifications made to the Session Description Protocol.  See the slides 
sdp.ps, and the documents
	ftp://ds.internic.net/internet-drafts/draft-ietf-mmusic-sdp.02.txt
	ftp://ftp.isi.edu/confctrl/docs/draft-ietf-mmusic-sdp.02.ps
These include simplification of time fields, the addition of new
attributes (e.g., for the quality of video encodings), and an
enhancement of the encryption keys (now an attribute/value pair as an
indirection for obtaining keys).  He then introduced the topic of
representing session capabilities (i.e., options from which to choose
to create a session as opposed to an instantiatable session as SDP
describes now).  A strawman extension to the syntax of SDP was
introduced and examples of its use were given.  Questions arose from
the group which identified that "potential sessions" were not a
well-understood concept.  Mark proposed that the current draft of SDP
be pushed forward as a proposed standard and that work begin to extend
SDP to support capability description.  Henning Schulzrinne objected
to the latter in favor of adopting a new syntax rather than extending
SDP itself.  He also said that he would raise an objection to the
former if advancing the current SDP draft implied that compatibility
with it would need to be maintained by a new session description
format/protocol.

Ross Finlayson (Live Networks, Inc.) spoke briefly about the work of the 
Calendaring and Scheduling Working Group and identified that isomorphism 
between a CALSCH event and an event represented in SDP was needed.  His input 
to that group has encouraged them to adopt the use of UTC time, etc. that
will make their event descriptions compatible with SDP.  He also
identified areas of potential incompatibility which implied that
participation by MMUSIC in this WG is needed to ensure compatible
results.

Mark Handley described the significant modifications made to the
Session Announcement Protocol.  See the slides sap.ps and the documents
	ftp://ds.internic.net/internet-drafts/draft-ietf-mmusic-sap.00.txt
	ftp://ds.internic.net/internet-drafts/draft-ietf-mmusic-sap.00.ps
(Please note that a previous PostScript-only version of this
Internet-Draft existed but the lack of a text version caused the reuse
of "00" for the 2nd version of the document).  These modifications
include removal of a padding bit from the SAP header, the addition of
a compression bit for indicating use of gzip (zlib) compression,
removal of the address-test message type, and the addition of a key id
field.  Open issues were identified and discussed which included
security, generation of a unique ID (guid's suggested as an option),
and restricting SAP to carry only SDP packets.

Mark Handley presented a "new" protocol, the Session Initiation
Protocol (SIP v2).  See the slides sip.ps and the documents
	ftp://ftp.isi.edu/confctrl/docs/draft-ietf-mmusic-sip-01.txt
	ftp://ftp.isi.edu/confctrl/docs/draft-ietf-mmusic-sip-01.ps
This protocol represents the unification of Handley/Schooler's Session
Invitation Protocol (SIP v1) and Schulzrinne's Simple Conference
Invitation Protocol (SCIP).  (Note that all are co-authors on this new
draft.)  The new protocol is specified to be carried over UDP or TCP,
uses an HTTP-like syntax and HTTP 1.1 status codes.  Proxy rules are
more tightly defined in SIP v2 but TCP/UDP translation proxies are to
be completed.  Open issues identified include: supporting capability
requests, adding additional support for transfers between telephone
and Internet.

Pete Cordell of British Telecom presented a description of research
work to develop the Simple Universal Call/Conference Establishment
Sequence Protocol (SUCCESS).  See the slides success.{ppt, ps} and 
the document
	ftp://ds.internic.net/internet-drafts/draft-cordell-success-00.txt
It is a single protocol for session management (cf the modular
approach employed in the specification of MMUSIC protocols) intended
to support the range of tightly to loosely controlled sessions.  It's
call model is based on a "hello-hello" paradigm.  Due to lack of time,
not much discussion on this protocol ensued.

Scott Petrack (Vocaltec, Ltd.) provided an overview of the VoIP (Voice on 
IP) Forum.  See the slides voip.{ppt, ps}.  VoIP is an IMTC group whose 
goal is to ensure and promote industry-wide interoperability of Internet 
voice communications products.  They will define technical guidelines for
two-party voice and other audio communications for compatibility with
traditional telephone service networks via telephony/IP
gateways. Their are currently working on items such as RTP payload
formats for DTMF tones and comfort noise, and an agent-based
architecture for pre-call setup called Call Management Agents
(CMA). Their mailing list is [email-masked] (requests to
[email-masked]); more information can be obtained
from http://www.imtc.org/n/n_whatnu.htm#voip.

Rob Lanphier (Progressive Networks) and Anup Rao (Netscape
Communication) provided an overview of the Real Time Stream Protocol
(RTSP).  See the slides rtsp_require.{ppt, ps} and the document
	ftp://ds.internic.net/internet-drafts/draft-ietf-mmusic-rtsp-00.txt
Two examples were presented to illustrate the protocol's use:
exchanging version information (see the slides rtsp_eg1.{ppt, ps})
and streaming a multimedia file (see the slides rtsp_eg2.{ppt, ps}).

Henning Schulzrinne (Columbia University) provided an overview of
RTSP'.  See the slides rtsp_prime1.ps (or rtsp_prime6.ps) and the
documents
	ftp://ds.internic.net/internet-drafts/draft-ietf-mmusic-stream.00.txt
	ftp://ds.internic.net/internet-drafts/draft-ietf-mmusic-stream.00.ps
RTSP' is an alternative proposal to RTSP inspired by the
Netscape/Progressive work but is more compatible with existing MMUSIC
protocols (SDP, SIP v2).

Open issues for real-time streaming were discussed which included text
vs binary representation of the protocol, stream control vs device
control, metafile/session descriptions, joining into existing
conferences, multi-client control of streams, and the use of UUIDs as
identifiers.  Daniel Adam (Microsoft Corp.) volunteered to create a
scenario describing the issues surrounding the use of UUIDs through
firewalls for future interaction with firewall vendors.

Akira Amamo (Hiroshima City University) presented the CamCorder Control
Protocol targeted for the control of video cameras and VCRs.  See the slides 
camcorder.{ppt, ps}.  The protocol is a text-based protocol designed after 
ftp.  Christian Huitema suggested that the authors consider writing an SNMP 
MIB for this purpose.  A disagreement about the appropriateness of text vs 
binary for such a protocol was cut short due to lack of time in the session.