FLUTE - File Delivery over Unidirectional Transport
RFC 3926

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Network Working Group                                           T. Paila
Request for Comments: 3926                                         Nokia
Category: Experimental                                           M. Luby
                                                        Digital Fountain
                                                             R. Lehtonen
                                                             TeliaSonera
                                                                 V. Roca
                                                       INRIA Rhone-Alpes
                                                                R. Walsh
                                                                   Nokia
                                                            October 2004

          FLUTE - File Delivery over Unidirectional Transport

Status of this Memo

   This memo defines an Experimental Protocol for the Internet
   community.  It does not specify an Internet standard of any kind.
   Discussion and suggestions for improvement are requested.
   Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2004).

Abstract

   This document defines FLUTE, a protocol for the unidirectional
   delivery of files over the Internet, which is particularly suited to
   multicast networks.  The specification builds on Asynchronous Layered
   Coding, the base protocol designed for massively scalable multicast
   distribution.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  2
       1.1.  Applicability Statement  . . . . . . . . . . . . . . . .  3
             1.1.1.  The Target Application Space . . . . . . . . . .  3
             1.1.2.  The Target Scale . . . . . . . . . . . . . . . .  4
             1.1.3.  Intended Environments  . . . . . . . . . . . . .  4
             1.1.4.  Weaknesses . . . . . . . . . . . . . . . . . . .  4
   2.  Conventions used in this Document. . . . . . . . . . . . . . .  5
   3.  File delivery  . . . . . . . . . . . . . . . . . . . . . . . .  5
       3.1.  File delivery session  . . . . . . . . . . . . . . . . .  6
       3.2.  File Delivery Table. . . . . . . . . . . . . . . . . . .  8
       3.3.  Dynamics of FDT Instances within file delivery session .  9
       3.4.  Structure of FDT Instance packets. . . . . . . . . . . . 11

Paila, et al.                 Experimental                      [Page 1]
RFC 3926                         FLUTE                      October 2004

             3.4.1.  Format of FDT Instance Header  . . . . . . . . . 12
             3.4.2.  Syntax of FDT Instance . . . . . . . . . . . . . 13
             3.4.3.  Content Encoding of FDT Instance . . . . . . . . 16
       3.5.  Multiplexing of files within a file delivery session . . 17
   4.  Channels, congestion control and timing  . . . . . . . . . . . 18
   5.  Delivering FEC Object Transmission Information . . . . . . . . 19
       5.1.  Use of EXT_FTI for delivery of FEC Object Transmission
             Information. . . . . . . . . . . . . . . . . . . . . . . 20
             5.1.1.  General EXT_FTI format . . . . . . . . . . . . . 20
             5.1.2.  FEC Encoding ID specific formats for EXT_FTI . . 21
       5.2.  Use of FDT for delivery of FEC Object Transmission
             Information. . . . . . . . . . . . . . . . . . . . . . . 25
   6.  Describing file delivery sessions. . . . . . . . . . . . . . . 25
   7.  Security Considerations  . . . . . . . . . . . . . . . . . . . 26
   8.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 29
   9.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 29
       Normative References . . . . . . . . . . . . . . . . . . . . . 29
       Informative References . . . . . . . . . . . . . . . . . . . . 30
   A.  Receiver operation (informative) . . . . . . . . . . . . . . . 32
   B.  Example of FDT Instance (informative). . . . . . . . . . . . . 33
       Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 34
       Full Copyright Statement . . . . . . . . . . . . . . . . . . . 35

1.  Introduction

   This document defines FLUTE version 1, a protocol for unidirectional
   delivery of files over the Internet.  The specification builds on
   Asynchronous Layered Coding (ALC), version 1 [2], the base protocol
   designed for massively scalable multicast distribution.  ALC defines
   transport of arbitrary binary objects.  For file delivery
   applications mere transport of objects is not enough, however.  The
   end systems need to know what the objects actually represent.  This
   document specifies a technique called FLUTE - a mechanism for
   signaling and mapping the properties of files to concepts of ALC in a
   way that allows receivers to assign those parameters for received
   objects.  Consequently, throughout this document the term 'file'
   relates to an 'object' as discussed in ALC.  Although this
   specification frequently makes use of multicast addressing as an