RObust Header Compression (ROHC): A Profile for TCP/IP (ROHC-TCP)
draft-sandlund-rfc4996bis-01

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Network Working Group                                       G. Pelletier
Internet-Draft                               InterDigital Communications
Obsoletes: 4996 (if approved)                                K. Sandlund
Intended status: Standards Track                                Ericsson
Expires: September 27, 2012                                 L-E. Jonsson

                                                                 M. West
                                                      Siemens/Roke Manor
                                                          March 26, 2012

   RObust Header Compression (ROHC): A Profile for TCP/IP (ROHC-TCP)
                      draft-sandlund-rfc4996bis-01

Abstract

   This document specifies a ROHC (Robust Header Compression) profile
   for compression of TCP/IP packets.  The profile, called ROHC-TCP,
   provides efficient and robust compression of TCP headers, including
   frequently used TCP options such as SACK (Selective Acknowledgments)
   and Timestamps.

   ROHC-TCP works well when used over links with significant error rates
   and long round-trip times.  For many bandwidth-limited links where
   header compression is essential, such characteristics are common.

   This specification obsoletes [RFC4996].  It fixes a technical issue
   with the SACK compression and clarifies other compression methods
   used.

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on September 27, 2012.

Copyright Notice

Pelletier, et al.      Expires September 27, 2012               [Page 1]
Internet-Draft                  ROHC-TCP                      March 2012

   Copyright (c) 2012 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  5
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  5
   3.  Background . . . . . . . . . . . . . . . . . . . . . . . . . .  6
     3.1.  Existing TCP/IP Header Compression Schemes . . . . . . . .  7
     3.2.  Classification of TCP/IP Header Fields . . . . . . . . . .  8
   4.  Overview of the TCP/IP Profile (Informative) . . . . . . . . . 10
     4.1.  General Concepts . . . . . . . . . . . . . . . . . . . . . 10
     4.2.  Compressor and Decompressor Interactions . . . . . . . . . 10
       4.2.1.  Compressor Operation . . . . . . . . . . . . . . . . . 10
       4.2.2.  Decompressor Feedback  . . . . . . . . . . . . . . . . 10
     4.3.  Packet Formats and Encoding Methods  . . . . . . . . . . . 11
       4.3.1.  Compressing TCP Options  . . . . . . . . . . . . . . . 11
       4.3.2.  Compressing Extension Headers  . . . . . . . . . . . . 11
     4.4.  Expected Compression Ratios with ROHC-TCP  . . . . . . . . 11
   5.  Compressor and Decompressor Logic (Normative)  . . . . . . . . 12
     5.1.  Context Initialization . . . . . . . . . . . . . . . . . . 12
     5.2.  Compressor Operation . . . . . . . . . . . . . . . . . . . 13
       5.2.1.  Compression Logic  . . . . . . . . . . . . . . . . . . 13
         5.2.1.1.  Optimistic Approach  . . . . . . . . . . . . . . . 13
         5.2.1.2.  Periodic Context Refreshes . . . . . . . . . . . . 14
       5.2.2.  Feedback Logic . . . . . . . . . . . . . . . . . . . . 14
         5.2.2.1.  Optional Acknowledgments (ACKs)  . . . . . . . . . 14
         5.2.2.2.  Negative Acknowledgments (NACKs) . . . . . . . . . 14
       5.2.3.  Context Replication  . . . . . . . . . . . . . . . . . 15
     5.3.  Decompressor Operation . . . . . . . . . . . . . . . . . . 15
       5.3.1.  Decompressor States and Logic  . . . . . . . . . . . . 15
         5.3.1.1.  Reconstruction and Verification  . . . . . . . . . 16
         5.3.1.2.  Detecting Context Damage . . . . . . . . . . . . . 17