Multicast Negative-Acknowledgment (NACK) Building Blocks
RFC 5401

Approval announcement
Draft of message to be sent after approval:

From: The IESG <>
To: IETF-Announce <>
Cc: Internet Architecture Board <>,
    RFC Editor <>, 
    rmt mailing list <>, 
    rmt chair <>
Subject: Protocol Action: 'Multicast Negative-Acknowledgment 
         (NACK) Building Blocks' to Proposed Standard 

The IESG has approved the following document:

- 'Multicast Negative-Acknowledgment (NACK) Building Blocks '
   <draft-ietf-rmt-bb-norm-revised-08.txt> as a Proposed Standard

This document is the product of the Reliable Multicast Transport Working 

The IESG contact persons are Magnus Westerlund and Lars Eggert.

A URL of this Internet-Draft is:

Technical Summary

    This document is an RMT Building Block that specifies data and 
    procedures useful for building a reliable multicast transport 
    protocol based on negative-acknowledgment (NACK) feedback.

    draft-ietf-rmt-bb-norm-revised specifically defines the following
    main components for use in protocol instantiations:

      1)  Multicast sender transmission strategies
      2)  NACK repair process with timer-based feedback suppression
      3)  Round-trip timing for adapting NACK and other timers

    draft-ietf-rmt-bb-norm-revised also includes context information
    defining the intended usage and applicability of the NACK building
    Block, in compliance with RFC 3269.

    Another RMT WG document, draft-ietf-rmt-pi-norm-revised, uses the
    specifications in this document to fully-define a NACK based
    reliable multicast transport protocol.

Working Group Summary

    There is consensus in the WG to publish this documents.

Document Quality

    The NORM Protocol Specification (RFC3940 and revised draft) is
    based upon the techniques described in this "building block" document.

    A public domain, open source implementation of the NORM protocol is
    available for use from the U.S. Naval Research Laboratory.  This
    implementation has been widely used in a number of applications,
    including military and commercial systems.  The INRIA has an
    implementation in progress.

    The content of this document was already reviewed and approved for
    publication as experimental RFC 3941. This document contains minor
    technical modifications.


    Lorenzo Vicisano is the Document Shepherd.
    Magnus Westerlund is the Responsible Area Director.