RFC 3843 (rfc3843) - Page 2 of 16

RObust Header Compression (ROHC): A Compression Profile for IP

Alternative Format: Original Text Document
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RFC 3843                 A ROHC Profile for IP                 June 2004


   Appendix A.  Detailed Procedures for Canceling Mode Transitions. . 12
       A.1.  Transition from Optimistic to Reliable Mode. . . . . . . 12
       A.2.  Transition from Unidirectional to Reliable Mode. . . . . 13
       A.3.  Transition from Reliable to Optimistic Mode. . . . . . . 13
       A.4.  Transition Back to Unidirectional Mode . . . . . . . . . 14
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 15
   Full Copyright Statement . . . . . . . . . . . . . . . . . . . . . 16

1.  Introduction

   The original RObust Header Compression (ROHC) RFC [RFC-3095] defines
   a framework for header compression, along with compression protocols
   (profiles) for IP/UDP/RTP, IP/ESP (Encapsulating Security Payload),
   IP/UDP, and also a profile for uncompressed packet streams.  The
   profile for uncompressed data was defined to provide a means to
   encapsulate all traffic over a link within ROHC packets.  Through
   this profile, the lower layers do not have to provide multiplexing
   for different packet types, but instead ROHC can handle any packet
   stream, even if compression profiles for all kinds of packet streams
   have not yet been defined or implemented over the link.

   Although the profile without compression is simple and can tunnel
   arbitrary packets, it has of course a major weakness in that it does
   not compress the headers at all.  When considering that normally all
   packets are expected to be IP [RFC-791, RFC-2460] packets, and that
   the IP header often represents a major part of the total header, a
   useful alternative to no compression would for most packets be
   compression of the IP header only.  Unfortunately, such a profile was
   not defined in [RFC-3095], and this has thus been identified as an
   important missing piece in the ROHC toolbox.

   This document addresses this missing compression support and defines
   a ROHC compression profile for IP [RFC-791, RFC-2460] only, similar
   to the IP/UDP profile defined by [RFC-3095], but simplified to
   exclude UDP.  Due to the similarities with the IP/UDP profile, the IP
   compression profile is described based on the IP/UDP profile, mainly
   covering differences.  The most important differences are a different
   way of terminating the static header chain, and the capability of
   compressing IP header chains of arbitrary length.

2.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC-2119].






Jonsson & Pelletier         Standards Track
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