2.8.13 Reliable Multicast Transport (rmt)

Last Modified: 2003-02-19

Chair(s):

Transport Area Director(s):

Transport Area Advisor:

Mailing Lists:

Description of Working Group:

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

Initial efforts will focus 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 expects to initially standardize three protocol instantiations, one each from the the following three families:

1) A NACK-based protocol 2) A Tree-based ACK protocol 3) An "Asynchronous Layered Coding protocol that uses Forward Error Correction

The WG will carry out protocol standardization by composing 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.

To assist in this standardization process, the WG will also complete work on three documents. The first describes the design-space in which the three one-to-many transport protocols will be developed. The second explains the concepts of building-blocks and protocol instantiations. The third provides guidelines to authors of drafts that specify building-blocks and protocol instantiations. These three documents will be initially submitted as WG drafts and subsequently proposed as Informational RFC.

The WG will generate and submit for standardization drafts of the following building-blocks for use in the construction of the three 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 three protocol instantiations: A NACK-based protocol, A Tree-based ACK protocol and an Open Loop protocol that uses Forward Error Correction.

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.

Goals and Milestones:

Internet-Drafts:

Request For Comments:

RMT WG Meeting, 56th IETF - San Francisco
Mon, March 17, 1530-1730

Many thanks to Marshall Eubanks for taking minutes.

Agenda:

 - New Charter discussion                                      Lorenzo 
Vicisano
 - NORM BB and PI updates                                      Brian 
Adamson
	draft-ietf-rmt-bb-norm-05.txt
	draft-ietf-rmt-pi-norm-06.txt
 - New "compact" scheme FEC BB                                 Mike Luby

	draft-ietf-rmt-bb-fec-supp-inband-00.txt
 - New FDALC draft                                             Toni Paila
	draft-paila-rmt-fdalc-00.txt
 - Kick off of the "Small Group Replication Service" subgroup  Rick 
Boivie

Please see slides for the new charter.
The main feedback on the new charter were:
  - delay the Milestone for TFMCC Experimental submission 
  - it was noted that GRA had been removed from the milestone due to 
perceived lack of resource and interest. It was decided to try and and find 
new resources to work on this. Tom Pusateri to investigate on this with the 
help of Brian Adamson and in coordination with the existing GRA 
authors. Tom to report on this in a timely fashion.
  - more comments on the "small-replication service" later in this 
report.

Brian Adamson on NORM BB and PI. Please see slides.
Brian felt that the "implementability" status of NORM is good as long as 
both BB and PI are used.

The WG was *strongly encouraged* to provide feedback on these two 
documents, soon to be pushed forward.

Mike Luby - ALC updates. Please see slides.
Mike is still waiting for WEBRC BB to be submitted for publication.

Mike Luby on new compact FEC BB. please see slides.

Toni Paila on New FDALC draft. Please see slides.
This is not a working group item yet. The WG decided that this was to 
become a WG item as a good completion of ALC. No need for changes in 
charter as this is only a completion of ALC.

Rick Boivie presented on Small group replication service. Please sees 
slides.

Long discussion followed on whether this work was pertinent to RMT and on 
whether this problem had been faced/resolved elsewhere in the 
transport or application areas. Many objected that this work did not 
belong in RMT. Other suggested possible alternatives, for example the 
peer-to-peer research group.

The consensus seemed to be that a BOF is needed, maybe a "end-system 
multicast" BOF.

• Presentation 1
• M. Luby

• Presentation 2
• Brain Adamson

• Presentation 3
• Rick Boivie