Unidirectional Lightweight Encapsulation (ULE) for Transmission of IP Datagrams over an MPEG-2 Transport Stream (TS)
RFC 4326

Network Working Group                                       G. Fairhurst
Request for Comments: 4326                        University of Aberdeen
Category: Standards Track                              B. Collini-Nocker
                                                  University of Salzburg
                                                           December 2005

           Unidirectional Lightweight Encapsulation (ULE) for
   Transmission of IP Datagrams over an MPEG-2 Transport Stream (TS)

Status of This Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2005).

Abstract

   The MPEG-2 Transport Stream (TS) has been widely accepted not only
   for providing digital TV services, but also as a subnetwork
   technology for building IP networks.

   This document describes a Unidirectional Lightweight Encapsulation
   (ULE) mechanism for the transport of IPv4 and IPv6 Datagrams and
   other network protocol packets directly over the ISO MPEG-2 Transport
   Stream as TS Private Data.  ULE specifies a base encapsulation format
   and supports an extension format that allows it to carry additional
   header information to assist in network/Receiver processing.

Fairhurst & Collini-Nocker  Standards Track                     [Page 1]
RFC 4326              ULE for IP over MPEG-2/DVB           December 2005

Table of Contents

   1. Introduction ....................................................3
   2. Conventions Used in This Document ...............................4
   3. Description of the Method .......................................8
   4. SNDU Format .....................................................9
      4.1. Destination Address Absent (D) Field ......................10
      4.2. Length Field ..............................................10
      4.3. End Indicator .............................................10
      4.4. Type Field ................................................10
           4.4.1. Type 1: Next-Header Type Fields ....................11
           4.4.2. Type 2: EtherType Compatible Type Fields ...........11
      4.5. SNDU Destination Address Field ............................12
      4.6. SNDU Trailer CRC ..........................................12
      4.7. Description of SNDU Formats ...............................13
           4.7.1. End Indicator ......................................14
           4.7.2. IPv4 SNDU Encapsulation ............................14
           4.7.3. IPv6 SNDU Encapsulation ............................15
   5. Extension Headers ..............................................16
      5.1. Test SNDU .................................................18
      5.2. Bridged Frame SNDU Encapsulation ..........................18
      5.3. Extension-Padding Optional Extension Header ...............21
   6. Processing at the Encapsulator .................................22
      6.1. SNDU Encapsulation ........................................22
      6.2. Procedure for Padding and Packing .........................24
   7. Receiver Processing ............................................25
      7.1. Idle State ................................................26
           7.1.1. Idle State Payload Pointer Checking ................26
      7.2. Processing of a Received SNDU .............................26
           7.2.1. Reassembly Payload Pointer Checking ................28
      7.3. Other Error Conditions ....................................28
   8. Summary ........................................................29
   9. Acknowledgements ...............................................29
   10. Security Considerations .......................................29
   11. IANA Considerations ...........................................30
      11.1. IANA Guidelines ..........................................30
   12. References ....................................................31
      12.1. Normative References .....................................31
      12.2. Informative References ...................................32
   Appendix A. SNDU Packing Examples .................................35
   Appendix B. SNDU Encapsulation ....................................40

Fairhurst & Collini-Nocker  Standards Track                     [Page 2]
RFC 4326              ULE for IP over MPEG-2/DVB           December 2005

1.  Introduction

   This document describes an encapsulation for the transport of IP