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Concluded WG Reliable Multicast Transport (rmt)

Note: The data for concluded WGs is occasionally incorrect.

WG Name Reliable Multicast Transport
Acronym rmt
Area Transport Area (tsv)
State Concluded
Charter charter-ietf-rmt-03 Approved
Document dependencies
Personnel Chair Brian Adamson
Area Director Martin Stiemerling
Liaison Contacts Brian Adamson, Lorenzo Vicisano
Mailing list Address
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Final Charter for Working Group

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

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

  • 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, and to address the RFC 2357 security requirements.

Generic mechanisms for router assist are also considered for an
additional building block. Initial work on the framework for
router-assist has already been performed, the WG will evaluate whether
to complete this task basing on available resource and interest.

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

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.


Date Milestone Associated documents
Sep 2010 Submit RMT Security documents for publication
Sep 2010 Submit FLUTE SDP document for publication

Done milestones

Date Milestone Associated documents
Done Submit RaptorQ FEC Scheme document for publication
Done Submit FCAST document for publication as Experimental
Done Submit all the RMT Eperimental Specifications published before July 05 for publication as Proposed Standard
Done Submit remaining congestion control building blocks (TFMCC, PGMCC) for publication as Experimental
Done Evaluate when and how the RMT Experimental specifications will be submitted for publication as Proposed Standard, and update this charter accordingly
Done Submit NACK building block and protocol instantiation for publication as Experimental
Done Submit WEBRC (congestion control building block) for publication as Experimental
Done WG Decision on whether to pursue the router-assist building block work. These milestones may have to be modified accordingly
Done Complete building blocks and protocol instantiations for ALC and submit for publication as Experimental RFC
Done Complete building-block drafts WG Last-Call and submit for publication as Proposed Standard
Done Submit Initial Draft for Congestion Control
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 two protocol instantiations.
Done Submit design-space, building-blocks, and guidelines drafts for publication as Informational RFCs