RObust Header Compression Version 2 (ROHCv2): Profiles for RTP, UDP, IP, ESP and UDP-Lite
RFC 5225

 
Document Type RFC - Proposed Standard (April 2008; Errata)
Last updated 2013-03-02
Replaces draft-ietf-rohc-rfc3095bis-improvements
Stream IETF
Formats plain text pdf html
Stream WG state (None)
Consensus Unknown
Document shepherd No shepherd assigned
IESG IESG state RFC 5225 (Proposed Standard)
Telechat date
Responsible AD Magnus Westerlund
Send notices to rohc-chairs@ietf.org, draft-ietf-rohc-rfc3095bis-rohcv2-profiles@ietf.org
Network Working Group                                       G. Pelletier
Request for Comments: 5225                                   K. Sandlund
Category: Standards Track                                       Ericsson
                                                              April 2008

             RObust Header Compression Version 2 (ROHCv2):
              Profiles for RTP, UDP, IP, ESP and UDP-Lite

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.

Abstract

   This document specifies ROHC (Robust Header Compression) profiles
   that efficiently compress RTP/UDP/IP (Real-Time Transport Protocol,
   User Datagram Protocol, Internet Protocol), RTP/UDP-Lite/IP (User
   Datagram Protocol Lite), UDP/IP, UDP-Lite/IP, IP and ESP/IP
   (Encapsulating Security Payload) headers.

   This specification defines a second version of the profiles found in
   RFC 3095, RFC 3843 and RFC 4019; it supersedes their definition, but
   does not obsolete them.

   The ROHCv2 profiles introduce a number of simplifications to the
   rules and algorithms that govern the behavior of the compression
   endpoints.  It also defines robustness mechanisms that may be used by
   a compressor implementation to increase the probability of
   decompression success when packets can be lost and/or reordered on
   the ROHC channel.  Finally, the ROHCv2 profiles define their own
   specific set of header formats, using the ROHC formal notation.

Pelletier & Sandlund        Standards Track                     [Page 1]
RFC 5225                    ROHCv2 Profiles                   April 2008

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   4
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Acronyms  . . . . . . . . . . . . . . . . . . . . . . . . . .   7
   4.  Background (Informative)  . . . . . . . . . . . . . . . . . .   7
     4.1.  Classification of Header Fields . . . . . . . . . . . . .   7
     4.2.  Improvements of ROHCv2 over RFC 3095 Profiles . . . . . .   8
     4.3.  Operational Characteristics of ROHCv2 Profiles  . . . . .  10
   5.  Overview of the ROHCv2 Profiles (Informative) . . . . . . . .  10
     5.1.  Compressor Concepts . . . . . . . . . . . . . . . . . . .  11
       5.1.1.  Optimistic Approach . . . . . . . . . . . . . . . . .  11
       5.1.2.  Tradeoff between Robustness to Losses and to
               Reordering  . . . . . . . . . . . . . . . . . . . . .  11
       5.1.3.  Interactions with the Decompressor Context  . . . . .  13
     5.2.  Decompressor Concepts . . . . . . . . . . . . . . . . . .  14
       5.2.1.  Decompressor State Machine  . . . . . . . . . . . . .  14
       5.2.2.  Decompressor Context Management . . . . . . . . . . .  17
       5.2.3.  Feedback Logic  . . . . . . . . . . . . . . . . . . .  19
   6.  ROHCv2 Profiles (Normative) . . . . . . . . . . . . . . . . .  19
     6.1.  Channel Parameters, Segmentation, and Reordering  . . . .  19
     6.2.  Profile Operation, Per-context  . . . . . . . . . . . . .  20
     6.3.  Control Fields  . . . . . . . . . . . . . . . . . . . . .  21
       6.3.1.  Master Sequence Number (MSN)  . . . . . . . . . . . .  21
       6.3.2.  Reordering Ratio  . . . . . . . . . . . . . . . . . .  21
       6.3.3.  IP-ID Behavior  . . . . . . . . . . . . . . . . . . .  22
       6.3.4.  UDP-Lite Coverage Behavior  . . . . . . . . . . . . .  22
       6.3.5.  Timestamp Stride  . . . . . . . . . . . . . . . . . .  22
       6.3.6.  Time Stride . . . . . . . . . . . . . . . . . . . . .  22
       6.3.7.  CRC-3 for Control Fields  . . . . . . . . . . . . . .  23
     6.4.  Reconstruction and Verification . . . . . . . . . . . . .  23
     6.5.  Compressed Header Chains  . . . . . . . . . . . . . . . .  24
     6.6.  Header Formats and Encoding Methods . . . . . . . . . . .  25
       6.6.1.  baseheader_extension_headers  . . . . . . . . . . . .  26
       6.6.2.  baseheader_outer_headers  . . . . . . . . . . . . . .  26
       6.6.3.  inferred_udp_length . . . . . . . . . . . . . . . . .  26
       6.6.4.  inferred_ip_v4_header_checksum  . . . . . . . . . . .  26
       6.6.5.  inferred_mine_header_checksum . . . . . . . . . . . .  27
       6.6.6.  inferred_ip_v4_length . . . . . . . . . . . . . . . .  28
       6.6.7.  inferred_ip_v6_length . . . . . . . . . . . . . . . .  28
       6.6.8.  Scaled RTP Timestamp Compression  . . . . . . . . . .  29
       6.6.9.  timer_based_lsb . . . . . . . . . . . . . . . . . . .  30
       6.6.10. inferred_scaled_field . . . . . . . . . . . . . . . .  31
Show full document text