The RObust Header Compression (ROHC) Framework
RFC 4995
Document | Type |
RFC - Proposed Standard
(July 2007; Errata)
Obsoleted by RFC 5795
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Authors | Lars-Erik Jonsson , Kristofer Sandlund , Ghyslain Pelletier | ||
Last updated | 2018-12-20 | ||
Stream | IETF | ||
Formats | plain text html pdf htmlized bibtex | ||
Stream | WG state | (None) | |
Document shepherd | No shepherd assigned | ||
IESG | IESG state | RFC 4995 (Proposed Standard) | |
Action Holders |
(None)
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||
Consensus Boilerplate | Unknown | ||
Telechat date | |||
Responsible AD | Magnus Westerlund | ||
Send notices to | (None) |
Network Working Group L-E. Jonsson Request for Comments: 4995 G. Pelletier Category: Standards Track K. Sandlund Ericsson July 2007 The RObust Header Compression (ROHC) Framework 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. Copyright Notice Copyright (C) The IETF Trust (2007). 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. Table of Contents 1. Introduction ....................................................3 2. Terminology .....................................................4 2.1. Acronyms ...................................................4 2.2. ROHC Terminology ...........................................4 3. Background (Informative) ........................................7 3.1. Header Compression Fundamentals ............................7 3.2. A Short History of Header Compression ......................7 4. Overview of Robust Header Compression (ROHC) (Informative) ......8 4.1. General Principles .........................................8 4.2. Compression Efficiency, Robustness, and Transparency ......10 4.3. Developing the ROHC Protocol ..............................10 Jonsson, et al. Standards Track [Page 1] RFC 4995 The ROHC Framework July 2007 4.4. Operational Characteristics of the ROHC Channel ...........11 4.5. Compression and Master Sequence Number (MSN) ..............13 4.6. Static and Dynamic Parts of a Context .....................13 5. The ROHC Framework (Normative) .................................14 5.1. The ROHC Channel ..........................................14 5.1.1. Contexts and Context Identifiers ...................14 5.1.2. Per-Channel Parameters .............................15 5.1.3. Persistence of Decompressor Contexts ...............16 5.2. ROHC Packets and Packet Types .............................16 5.2.1. General Format of ROHC Packets .....................17 5.2.1.1. Format of the Padding Octet ...............17 5.2.1.2. Format of the Add-CID Octet ...............18 5.2.1.3. General Format of Header ..................18 5.2.2. Initialization and Refresh (IR) Packet Types .......19 5.2.2.1. ROHC IR Packet Type .......................20 5.2.2.2. ROHC IR-DYN Packet Type ...................20 5.2.3. ROHC Initial Decompressor Processing ...............21 5.2.4. ROHC Feedback ......................................22 5.2.4.1. ROHC Feedback Format ......................23 5.2.5. ROHC Segmentation ..................................25 5.2.5.1. Segmentation Usage Considerations .........25 5.2.5.2. Segmentation Protocol .....................26 5.3. General Encoding Methods ..................................27 5.3.1. Header Compression CRCs, Coverage and Polynomials ..27 5.3.1.1. 8-bit CRCs in IR and IR-DYN Headers .......27 5.3.1.2. 3-bit CRC in Compressed Headers ...........27 5.3.1.3. 7-bit CRC in Compressed Headers ...........28 5.3.1.4. 32-bit Segmentation CRC ...................28 5.3.2. Self-Describing Variable-Length Values .............29 5.4. ROHC UNCOMPRESSED -- No Compression (Profile 0x0000) .....29 5.4.1. IR Packet ..........................................30 5.4.2. Normal Packet ......................................31 5.4.3. Decompressor Operation .............................31 5.4.4. Feedback ...........................................32 6. Overview of a ROHC Profile (Informative) .......................32Show full document text