The RObust Header Compression (ROHC) Framework
RFC 5795

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Internet Engineering Task Force (IETF)                       K. Sandlund
Request for Comments: 5795                                  G. Pelletier
Obsoletes: 4995                                                 Ericsson
Category: Standards Track                                   L-E. Jonsson
ISSN: 2070-1721                                               March 2010

             The RObust Header Compression (ROHC) Framework

Abstract

   The Robust Header Compression (ROHC) protocol provides an efficient,
   flexible, and future-proof header compression concept.  It is
   designed to operate efficiently and robustly over various link
   technologies with different characteristics.

   The ROHC framework, along with a set of compression profiles, was
   initially defined in RFC 3095.  To improve and simplify the ROHC
   specifications, this document explicitly defines the ROHC framework
   and the profile for uncompressed separately.  More specifically, the
   definition of the framework does not modify or update the definition
   of the framework specified by RFC 3095.

   This specification obsoletes RFC 4995.  It fixes one interoperability
   issue that was erroneously introduced in RFC 4995, and adds some
   minor clarifications.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc5795.

Sandlund, et al.             Standards Track                    [Page 1]
RFC 5795                     ROHC Framework                   March 2010

Copyright Notice

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   document authors.  All rights reserved.

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   This document may contain material from IETF Documents or IETF
   Contributions published or made publicly available before November
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   Without obtaining an adequate license from the person(s) controlling
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   it for publication as an RFC or to translate it into languages other
   than English.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  5
     2.1.  Acronyms . . . . . . . . . . . . . . . . . . . . . . . . .  5
     2.2.  ROHC Terminology . . . . . . . . . . . . . . . . . . . . .  5
   3.  Background (Informative) . . . . . . . . . . . . . . . . . . .  8
     3.1.  Header Compression Fundamentals  . . . . . . . . . . . . .  8
     3.2.  A Short History of Header Compression  . . . . . . . . . .  9
   4.  Overview of ROHC (Informative) . . . . . . . . . . . . . . . . 10
     4.1.  General Principles . . . . . . . . . . . . . . . . . . . . 10
     4.2.  Compression Efficiency, Robustness, and Transparency . . . 11
     4.3.  Developing the ROHC Protocol . . . . . . . . . . . . . . . 12
     4.4.  Operational Characteristics of the ROHC Channel  . . . . . 13
     4.5.  Compression and Master Sequence Number (MSN) . . . . . . . 14
     4.6.  Static and Dynamic Parts of a Context  . . . . . . . . . . 15
   5.  The ROHC Framework (Normative) . . . . . . . . . . . . . . . . 15
     5.1.  The ROHC Channel . . . . . . . . . . . . . . . . . . . . . 15
       5.1.1.  Contexts and Context Identifiers . . . . . . . . . . . 15
       5.1.2.  Per-Channel Parameters . . . . . . . . . . . . . . . . 16
       5.1.3.  Persistence of Decompressor Contexts . . . . . . . . . 17

Sandlund, et al.             Standards Track                    [Page 2]
RFC 5795                     ROHC Framework                   March 2010

     5.2.  ROHC Packets and Packet Types  . . . . . . . . . . . . . . 17