For the Mar 6 agenda: revision of RMT charter

[Allison Mankin <mankin@psg.com>]

[This charter rev cuts out two work items that were not 
 progressing at all: the TRACK and GRA families.
 It adds a sub-group after a lot of discussions
 among ourselves and Routing - see the text...this sub-group
 is a part of the xcast work, just the most stable and
 least research-y part of it]

Reliable Multicast Transport (rmt) Working Group

Chairs:
Roger Kermode <roger.kermode@motorola.com>
Lorenzo Vicisano <lorenzo@cisco.com>

[no changes in boilerplate]



The purpose of this WG is to standardize reliable multicast transport.

Initial efforts have focused solely on the standardization of the
one-to-many transport of large amounts of data. Due to the large
number of applications that fall into this category, and the sometimes
orthogonal requirements these applications exhibit, it is believed
that a "one size fits all" protocol will be unable to meet the
requirements of all applications. In recognition of this observation,
this working group will standardize two protocol instantiations, 
initially as Experimental protocols, and then as warranted, in the
standards track, from the following families:

1) A NACK-based protocol.
2) An "Asynchronous Layered Coding protocol that uses Forward Error
   Correction.

In addition, the rmt WG will have a sub-group for a different task.
This sub-group will develop a protocol for a simple unicast
replication service that is specifically designed to address the need
of very-small-scale multicast sessions. The goal of this protocol is
to provide a small-scale replication solution that does not require
per-session state in all parts of the network crossed by the session
traffic, unlike native IP multicast.  The applicability of this
protocol is to situations where end-to-end unicast replication is not
appropriate due to bandwidth limitation in some part of the
network (usually last-mile links).

It should be noted that this simple unicast replication work is in a
sub-group because a strict interpretation of this service would
determine that it falls somewhat outside the transport domain (other
than congestion control) and has more routing issues than most of the
other work in rmt.  Given that the bulk of the experts who would be
qualified to comment on this work item are already active participants
in the rmt WG, the Routing and Transport Area Directors have concluded
to make an exception and develop it in this working group's sub-group
instead of forming a new working group.

The WG will carry out protocol standardization in general by composing a 
a set of RFCs that specify

- building blocks: A set of easily-separable coarse-grained modular
components that are common to multiple protocols along with abstract
APIs that define a building block's access methods and their
arguments.

- protocol instantiations: Specifications that define the necessary
gluing logic and minimal additional functionality required to realize
a working protocol from one or more building blocks. These
specifications will also include an abstract API that defines the
interface between the protocol implementation and an application.

The WG has previously completed work on three documents to assist in
the standardization process. RFC2887 describes the design-space in
which the one-to-many transport protocols will be developed. RFC3048
explains the concepts of building-blocks and protocol
instantiations. RFC3269 provides guidelines to authors of drafts that
specify building-blocks and protocol instantiations.

The WG will generate and submit for standardization drafts of the
following building-blocks for use in the construction of the two
protocols: congestion control, negative acknowledgments, forward error
correction, generic mechanisms for router assist, and to address the
RFC 2357 security requirements.

The WG will also standardize and generate RFCs for the following two
protocol instantiations: A NACK-based protocol, and an Asynchronous
Layered Coding (ALC) protocol that uses Forward Error Correction.
RFC 3450 is the Experimental RFC of the ALC protocol instantiation.

If new requirements are identified that cannot be satisfied with the
building-blocks and protocol instantiations described above, the Area
Directors in consultation with the IESG may add additional
building-blocks and protocol instantiations to the working group
deliverables.

This working group will work closely with the Internet Research Task
Force (IRTF) groups on Reliable Multicast (RMRG) and 
Secure Multicast (SMUG), especially for meeting the congestion control
and security requirements mandated by RFC 2357. This working group may
work with the Area Directors to recharter to standardize reliable
multicast for additional scenarios beyond the one-to-many transport of
bulk data once they are sufficiently well understood.

MILESTONES

Done Submit design-space, building-blocks, and guidelines drafts for
     publication as Informational RFCs

Done Initial Drafts for the following building blocks: negative
     acknowledgments, forward error correction, a generic signaling
     mechanism for router assist, and transport protection

Done   Submit Initial Drafts for the three protocol instantiations.  

Done    Review drafts at the Adelaide IETF  

Done    Submit Initial Draft for Congestion Control  

Done Complete building-block drafts WG Last-Call and submit for
     publication as Proposed Standard

Done Complete building blocks and protocol instantiations for
     ALC and submit for publication as Experimental

The following are tentative:
MAY 03 Submit TFMCC congestion control building block for 
       publication as Experimental

AUG 03 Submit WEBRC (congestion control for ALC) building
       block for publication as Experimental

AUG 03 Submit NACK protocol instantiation for publication
       as Experimental

AUG 03 Submission of simple unicast replication building block 
       including congestion control for publication as Experimental

DEC 03 ALC protocol instantiation and building blocks 
       submitted for publication as Proposed Standard.

DEC 03 TFMCC submitted for publication as Proposed
       Standard.

DEC 03 Conclude working group, unless determined with Area Directors
       that there is additional work for the charter