RFC 3695 (rfc3695) - Page 2 of 13


Compact Forward Error Correction (FEC) Schemes



Alternative Format: Original Text Document



RFC 3695                      FEC Schemes                  February 2004


       4.2.  Block-Stream Delivery. . . . . . . . . . . . . . . . . . 10
   5.  Security Considerations. . . . . . . . . . . . . . . . . . . . 10
   6.  IANA Considerations. . . . . . . . . . . . . . . . . . . . . . 10
   7.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 11
       7.1.  Normative References . . . . . . . . . . . . . . . . . . 11
       7.2.  Informative References . . . . . . . . . . . . . . . . . 12
   8.  Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 12
   9.  Full Copyright Statement . . . . . . . . . . . . . . . . . . . 13

1.  Introduction

   This document describes two new Forward Error Correction (FEC)
   schemes corresponding to FEC Encoding IDs 0 and 130 which supplement
   the FEC schemes corresponding to FEC Encoding IDs 128 and 129
   described in the FEC Building Block [4].

   The new FEC schemes are particularly applicable when an object is
   partitioned into equal-length source blocks.  In this case, the
   source block length common to all source blocks can be communicated
   out-of-band, thus saving the additional overhead of carrying the
   source block length within the FEC Payload ID of each packet.  The
   new FEC schemes are similar to the FEC schemes with FEC Encoding ID
   128 defined in RFC 3452 [4], except that the FEC Payload ID is half
   as long.  This is the reason that these new FEC schemes are called
   Compact FEC schemes.

   The primary focus of FEC Encoding IDs 128 and 129 is to reliably
   deliver bulk objects of known length.  The FEC schemes described in
   this document are designed to be used for both reliable delivery of
   bulk objects of known length, and for the delivery of a stream of
   source blocks for an object of indeterminate length.  Within the
   block-stream delivery model, reliability guarantees can range from
   acknowledged reliable delivery of each block to unacknowledged
   enhanced-reliability delivery of time-sensitive blocks, depending on
   the properties of the protocol instantiation in which the FEC scheme
   is used.  Acknowledged reliable block-stream delivery is similar in
   spirit to the byte-stream delivery that TCP offers, except that the
   unit of delivery is a block of data instead of a byte of data.  In
   the spirit of a building block (see RFC 3048 [6]), the FEC schemes
   described in this document can be used to provide reliability for
   other service models as well.

   The two new FEC Encoding IDs 0 and 130 are described in Section 2,
   and this supplements Section 5 of the FEC building block [4].
   Section 3 of this document describes the Fully-Specified FEC scheme
   corresponding to the FEC Encoding ID 0.  This Fully-Specified FEC





Luby & Vicisano               Experimental