RObust Header Compression (ROHC): A Link-Layer Assisted Profile for IP/UDP/RTP
RFC 3242
Document | Type |
RFC - Proposed Standard
(April 2002; No errata)
Obsoleted by RFC 4362
|
|
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Last updated | 2013-03-02 | ||
Stream | IETF | ||
Formats | plain text pdf html bibtex | ||
Stream | WG state | (None) | |
Document shepherd | No shepherd assigned | ||
This information refers to IESG processing after the RFC was initially published: | |||
IESG | IESG state | RFC 3242 (Proposed Standard) | |
Consensus Boilerplate | Unknown | ||
Telechat date | |||
Responsible AD | Allison Mankin | ||
IESG note | Responsible: Finished | ||
Send notices to | <cabo@tzi.org>, <lars-erik.jonsson@ericsson.com> |
Network Working Group L-E. Jonsson Request for Comments: 3242 G. Pelletier Category: Standards Track Ericsson April 2002 RObust Header Compression (ROHC): A Link-Layer Assisted Profile for IP/UDP/RTP 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 Internet Society (2002). All Rights Reserved. Abstract This document defines a ROHC (Robust Header Compression) profile for compression of IP/UDP/RTP (Internet Protocol/User Datagram Protocol/Real-Time Transport Protocol) packets, utilizing functionality provided by the lower layers to increase compression efficiency by completely eliminating the header for most packets during optimal operation. The profile is built as an extension to the ROHC RTP profile. It defines additional mechanisms needed in ROHC, states requirements on the assisting layer to guarantee transparency, and specifies general logic for compression and decompression making use of this header-free packet. Table of Contents 1. Introduction....................................................2 2. Terminology.....................................................4 3. Overview of the Link-Layer Assisted Profile.....................5 3.1. Providing Packet Type Identification.....................6 3.2. Replacing the Sequence Number............................6 3.3. CRC Replacement..........................................7 3.4. Applicability of This Profile............................7 4. Additions and Exceptions Compared to ROHC RTP...................8 4.1. Additional Packet Types..................................8 4.1.1. No-Header Packet (NHP)..........................8 4.1.2. Context Synchronization Packet (CSP)............8 4.1.3. Context Check Packet (CCP)......................9 Jonsson, et. al Standards Track [Page 1] RFC 3242 A Link-Layer Assisted ROHC RTP April 2002 4.2. Interfaces Towards the Assisting Layer..................11 4.2.1. Interface, Compressor to Assisting Layer.......11 4.2.2. Interface, Assisting Layer to Decompressor.....12 4.3. Optimistic Approach Agreement...........................13 4.4. Fast Context Initialization, IR Redefinition............13 4.5. Feedback Option, CV-REQUEST.............................14 4.6. Periodic Context Verification...........................15 4.7. Use of Context Identifier...............................15 5. Implementation Issues..........................................15 5.1. Implementation Parameters and Signals...................15 5.1.1. Implementation Parameters at the Compressor....16 5.1.2. Implementation Parameters at the Decompressor..17 5.2. Implementation over Various Link Technologies...........18 6. IANA Considerations............................................18 7. Security Considerations........................................18 8. Acknowledgements...............................................18 9. References.....................................................19 10. Authors' Addresses.............................................20 11. Full Copyright Statement.......................................21 1. Introduction Header compression is a technique used to compress and transparently decompress the header information of a packet on a per-hop basis, utilizing redundancy within individual packets and between consecutive packets within a packet stream. Over the years, several protocols [VJHC, IPHC] have been developed to compress the network and transport protocol headers [IPv4, IPv6, UDP, TCP], and these schemes have been successful in improving efficiency over many wired bottleneck links, such as modem connections over telephone networks. In addition to IP, UDP, and TCP compression, an additional compression scheme called Compressed RTP [CRTP] has been developed to further improve compression efficiency for the case of real-time traffic using the Real-Time Transport Protocol [RTP]. The schemes mentioned above have all been designed taking into account normal assumptions about link characteristics, which traditionally have been based on wired links only. However, with anShow full document text