RObust Header Compression (ROHC): ROHC over Channels That Can Reorder Packets
draft-ietf-rohc-over-reordering-03

The information below is for an old version of the document that is already published as an RFC
Document Type RFC Internet-Draft (rohc WG)
Authors Kristofer Sandlund  , Ghyslain Pelletier 
Last updated 2013-03-02 (latest revision 2005-05-17)
Stream Internet Engineering Task Force (IETF)
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IESG IESG state RFC 4224 (Informational)
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Responsible AD Allison Mankin
Send notices to cabo@tzi.org, lars-erik.jonsson@ericsson.com
Network Working Group                                       G. Pelletier
INTERNET-DRAFT                                              L-E. Jonsson
Expires: November 2005                                       K. Sandlund
                                                                Ericsson
                                                            May 16, 2005

                      RObust Header Compression (ROHC):
                 ROHC over Channels that can Reorder Packets
                  <draft-ietf-rohc-over-reordering-03.txt>

Status of this memo

   By submitting this Internet-Draft, each author represents that any
   applicable patent or other IPR claims of which he or she is aware
   have been or will be disclosed, and any of which he or she becomes
   aware will be disclosed, in accordance with Section 6 of BCP 79.

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   This document is a submission of the IETF ROHC WG. Comments should be
   directed to the ROHC WG mailing list, rohc@ietf.org.

Abstract

   RObust Header Compression (ROHC), RFC 3095, defines a framework for
   header compression, along with a number of compression protocols
   (profiles). One operating assumption for the profiles defined in RFC
   3095 is that the channel between compressor and decompressor is
   required to maintain packet ordering. This document discusses aspects
   of using ROHC over channels that can reorder packets. It provides
   guidelines on how to implement existing profiles over such channels,
   as well as suggestions for the design of new profiles.

Pelletier, et al.                                               [Page 1]
INTERNET-DRAFT        ROHC over Reordering Channels         May 16, 2005

Table of Contents

   1. Introduction.....................................................3
   2. Terminology......................................................3
   3. Applicability of this Document to ROHC Profiles..................5
      3.1. Profiles within Scope.......................................5
      3.2. Profiles with Special Considerations........................5
      3.3. Profiles Incompatible with Reordering.......................5
   4. Background.......................................................6
      4.1. Reordering Channels.........................................6
      4.2. Robustness Principles of ROHC...............................6
         4.2.1. Optimistic Approach (U/O-mode).........................6
         4.2.2. Secure Reference Principle (R-mode)....................7
   5. Problem Description..............................................7
      5.1. ROHC and Reordering Channels................................7
         5.1.1. LSB Interpretation Interval and Reordering.............7
         5.1.2. Reordering of Packets in R-mode........................9
            5.1.2.1. Updating Packets..................................9
            5.1.2.2. Non-Updating Packets..............................9
         5.1.3. Reordering of Packets in U/O-mode.....................10
         5.1.4. Reordering on the Feedback Channel....................10
         5.1.5. List Compression......................................11
         5.1.6. Reordering and Mode Transitions.......................11
      5.2. Consequences of Reordering.................................12
         5.2.1. Functionality Incompatible with Reordering............12
         5.2.2. Context Damage (Loss of Synchronization)..............12
         5.2.3. Detected Decompression Failures (U/O/R-mode)..........13
         5.2.4. Undetected Decompression Failures (R-mode only).......13
   6. Making ROHC Tolerant against Reordering.........................13
      6.1. Properties of ROHC Implementations.........................13
         6.1.1. Compressing Headers with Robustness against Reordering14
            6.1.1.1. Reordering and the Optimistic Approach...........14
            6.1.1.2. Reordering and the Secure Reference Principle....14
            6.1.1.3. Robust Selection of Compressed Header............14
         6.1.2. Implementing a Reordering Tolerant Decompressor.......15
            6.1.2.1. Decompressor Feedback Considerations.............15
            6.1.2.2. Considerations for Local Repair Mechanisms.......16
      6.2. Specifying ROHC Profiles with Robustness against Reordering16
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