Internet Info 1997 December/Internet_Info_CD-ROM_Walnut_Creek_December_1997.iso/ietf/94dec/area.transport.94dec.txt

Text File | 1995-02-28 | 10KB | 206 lines

Transport Area

Director:


   o Allison Mankin:  [e-mail]


Area Summary reported by Allison Mankin/NRL

The Transport Services Area deals with protocols and algorithms that
provide end-to-end transmission services in the Internet.  We maintain
the notion of transport services, not just transport protocols, because
of the increasing variety of end-to-end requirements that the Internet
meets or will have to meet soon.

The members of the Transport Area Directorate are:


               Dave Borman     [e-mail]
               Sally Floyd     [e-mail]
               Jim Hughes      [e-mail]
               Matt Mathis     [e-mail]
               Greg Minshall   [e-mail]
               Eve Schooler    [e-mail]
               John Wroclawski [e-mail]
               Lixia Zhang     [e-mail]


The Transport Area Directorate is primarily responsible for quality
review of the working groups.  It meets regularly on the MBONE to plan
for each upcoming IETF. It has a mailing list, but its location is in
transition, with the Area Director's move to ISI (in a new East Coast
lab).

Here is some news of the Area from between the meetings and San Jose,
followed by group meeting summaries.


   o We will soon plan what Transport Next Generation work should begin,
     as the mid-term result of the TCPng BOF reported below.

   o The ONCRPC Working Group was in hiatus for San Jose, while the
     IETF's agreement with Sun was worked out.  Soon on the TSV agenda
     will be determining how the second half of the ONCRPC charter
     (enhancing the standards once they were documented) should go.

   o Richard Stevens, the author of TCP/IP Illustrated, has been asked
     to write an RFC documenting TCP's adaptive algorithms, since Sally
     Floyd reviewed that chapter in TCP/IP Illustrated Vol.  2 and
     reported that it was extremely accurate and clear.  He will try to
     do so before the next IETF.

   o The Thin-OSI Working Group completed its charter and concluded
     between Toronto and San Jose.

   o The TMUX proposal, developed in a TSV BOF, received an extended
     Last Call and was elevated to Proposed Standard (RFC 1692).

   o Of the TSV working groups, four met in San Jose, and one BOF was
     hosted, TCPng, a review in conjunction with IPng.

   o The ONC Remote Procedure Call Working Group (ONCRPC) and the TCP
     Large Windows Working Group (TCPLW) are dormant.



Next Generation TCP BOF (TCPNG)


The TCPng BOF was convened to consider what changes need to be made to
TCP for the transition to IPv6, and whether any other new features
should be added at this time.  The meeting distinguished TCP6, the
minimal changes to operate over IPv6, from a TCPng, a wonderful new
TCP-like protocol.  It discussed a number of different possible features
that might be included in TCPng, and suggested that the Transport
Service Area Director might set up a working group to talk about next
generation transport protocols.



Audio/Video Transport Working Group (AVT)


A report was presented on the changes to the Real-time Transport
Protocol draft since the July version (-05).  These changes were all
small, though a few did introduce incompatibilities.  There were no
objections to these changes.  However, there was a surprising amount of
debate about the jitter parameter in the Reception Report which had not
changed except that the algorithm had been defined.  As a result, a
second session was scheduled to allow completing the planned
presentations.  During the second session, a compromise solution was
devised:  the jitter field remained unchanged, but the ``cumulative
packets received'' was changed to ``cumulative packets lost'' and
reduced to 24 bits.  The freed 8 bits will contain a ``fraction of
packets lost'' allowing short-term loss measurements with singleton
reception reports.  With this issue settled, the draft editing will be
completed and the draft will be submitted for Area Directorate review.

Additional presentations were given on the implementation of RTPv2 in
vic (by Steve McCanne) and Loki (by Frank Kastenholz), and on the new
draft Packet Format for Encapsulation of MPEG in RTP (by Gerard
Fernando).


Integrated Services Working Group (INTSERV)


The integrated services working group (INT-SRV) held two meetings at the
San Jose IETF. At these meetings the group discussed several parts of a
``reusable framework'' approach to providing quality of service control
in the Internet.  The key goal of this approach is to allow new services
to be deployed in an evolutionary, market-driven manner, while
maintaining backward compatibility and (re)using standard components.

The first meeting began with a brief presentation describing this new
approach and how it differs from the group's previously proposed path.
John Wroclawski's presentation discussed goals, described four
components (QM manager, setup protocols, traffic specifiers, and service
specification templates), and briefly described the impact of this
approach on the work items adopted at the Toronto IETF.

The majority of the first meeting was devoted to a discussion of the
Quality of Service Manager, an abstraction layer designed to isolate
applications from the specific details of services provided by an
internet.  Dave Clark gave a general presentation of the QM idea, its
uses, and how it might be realised in practice.  Craig Partridge
discussed a binding of the QM to Berkeley sockets.  Both of these
presentations describe early work, and the authors received significant
feedback from the working group.

The meeting closed with a brief discussion of the merits of the
framework approach to providing integrated services.  A show of hands
revealed essentially complete consensus that the new approach was
preferred to the alternative of mandating a single set of services
throughout the Internet.

The group continued the discussion of framework components in the second
meeting.  Scott Shenker presented a preliminary draft of a service
specification requirements document.  The document has two parts.  The
first specifies a ``template'' for defining services, including router
behavior, composition rules, and the like.  The remainder of the
document gives several examples of the use of this template.  The
intention is that the template format become a standard, but for now,
the example services are informational.  The group agreed that this
draft was a good base for continued work.

Craig Partridge gave a presentation about traffic specifications
(``flowspecs'') and whether these are a reusable component or specific
to a particular service.  After some discussion, the group appeared to
find some merit to common flowspecs, but believed that further concrete
evidence of their usefulness was required.  Further discussion centered
on the use of RFC 1363 or the Windows Sockets version 2.0 specification
as a possible starting point for experimental implementations.

John Wroclawski presented a proposal for initial deployment of
integrated service capabilities in the July '95 time frame.  The
proposal includes RSVP, a level-of-effort predictive service, and
management and monitoring capability.  John asked about interest in a
small implementors group to further this work, and received several
positive responses during and after the meeting.

The second meeting closed with a technical discussion about token bucket
filters.  TBFs are widely proposed today as traffic descriptors and
shapers, but recent work by Mark Garrett and Craig Partridge suggests
some limitations.  This is directly relevant to the flowspec discussion
described above, and will need to be better understood in the future.


Multiparty Multimedia Session Control Working Group (MMUSIC)

In an effort to make the working group aware of other standardization
efforts, two brief presentations were given on ITU teleconferencing
efforts.  Next, an overview of both a centralized and a distributed
implementation of the Shenker-Weinrib-Schooler agreement protocol was
given -- 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 then given, focusing on derived functional requirements
for both session control protocols and session descriptions.  An
overview of inter-system (horizontal) and intra-system (vertical)
session control requirements was presented which left open questions on
the transport and semantic requirements.  A presentation was then given
which identified additional requirements for the ``sd'' protocol and a
discussion of proposed extension followed.  Finally, the current goals
and milestones were reviewed and a list of potential working group
documents was discussed.


Resource Reservation Setup Protocol Working Group (RSVP)

The RSVP Working Group met for two sessions during the San Jose IETF.
The first session began with a brief review of implementation status and
a description of the MM '94 demo.  The rest of the first meeting was
devoted to reports from all those who took study action items at the
Toronto meeting.  Each report included a recommendation to the working
group.

The second session began with reviews of some new technical issues, not
previously discussed.  Then the working group developed a list of
features to be included in version 1 RSVP. This list will serve as the
basis for revision of the specification and review, hopefully allowing
submission as a Proposed Standard in July 1995.