The Session Initiation Protocol (SIP) and Session Description Protocol (SDP) Static Dictionary for Signaling Compression (SigComp)
RFC 3485
Document | Type |
RFC - Proposed Standard
(March 2003; No errata)
Updated by RFC 4896
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Authors | Miguel GarcĂa , Richard Price , Carsten Bormann , Adam Roach , Joerg Ott | ||
Last updated | 2015-10-14 | ||
Stream | IETF | ||
Formats | plain text html pdf htmlized bibtex | ||
Stream | WG state | WG Document | |
Document shepherd | No shepherd assigned | ||
IESG | IESG state | RFC 3485 (Proposed Standard) | |
Consensus Boilerplate | Unknown | ||
Telechat date | |||
Responsible AD | Allison Mankin | ||
Send notices to | <rohan@cisco.com>, <dean.willis@softarmor.com> |
Network Working Group M. Garcia-Martin Request for Comments: 3485 Ericsson Category: Standards Track C. Bormann J. Ott TZI/Uni Bremen R. Price Siemens/Roke Manor A. B. Roach dynamicsoft February 2003 The Session Initiation Protocol (SIP) and Session Description Protocol (SDP) Static Dictionary for Signaling Compression (SigComp) 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 (2003). All Rights Reserved. Abstract The Session Initiation Protocol (SIP) is a text-based protocol for initiating and managing communication sessions. The protocol can be compressed by using Signaling Compression (SigComp). Similarly, the Session Description Protocol (SDP) is a text-based protocol intended for describing multimedia sessions for the purposes of session announcement, session invitation, and other forms of multimedia session initiation. This memo defines the SIP/SDP-specific static dictionary that SigComp may use in order to achieve higher efficiency. The dictionary is compression algorithm independent. Garcia-Martin, et al. Standards Track [Page 1] RFC 3485 SIP and SDP Static Dictionary for SigComp February 2003 Table of Contents 1. Introduction.....................................................2 2. Design considerations............................................3 3. Binary representation of the SIP/SDP dictionary..................5 4. Security Considerations.........................................13 5. IANA Considerations.............................................13 6. Acknowledgements................................................14 7. References......................................................14 7.1 Normative References........................................14 7.2 Informative References......................................14 Appendix A. SIP input strings to the SIP/SDP static dictionary.....17 Appendix B. SDP input strings to the SIP/SDP static dictionary.....26 Authors' Addresses.................................................29 Full Copyright Statement...........................................30 1. Introduction SIP [3] and SDP [24] are text-based protocols that use the UTF-8 charset (RFC 2279 [5]). SIP and SDP were designed for rich bandwidth links. However, when SIP/SDP is run over narrow bandwidth links, such as radio interfaces or low speed serial links, the session setup time increases substantially, compared to an operation over a rich bandwidth link. The session setup time can decrease dramatically if the SIP/SDP signaling is compressed. The signaling compression mechanisms specified in SigComp [1] provide a multiple compression/decompression algorithm framework to compress and decompress text-based protocols such as SIP and SDP. When compression is used in SIP/SDP, the compression achieves its maximum rate once a few message exchanges have taken place. This is due to the fact that the first message the compressor sends to the decompressor is only partially compressed, as there is not a previous stored state to compress against. As the goal is to reduce the session setup time as much as possible, it seems sensible to investigate a mechanism to boost the compression rate from the first message. In this memo we introduce the static dictionary for SIP and SDP. The dictionary is to be used in conjunction with SIP, SDP and SigComp. The static SIP/SDP dictionary constitutes a SigComp state that can be referenced in the first SIP message that the compressor sends out. Garcia-Martin, et al. Standards Track [Page 2] RFC 3485 SIP and SDP Static Dictionary for SigComp February 2003 2. Design considerations The static SIP/SDP dictionary is a collection of well-known strings that appear in most of the SIP and SDP messages. The dictionary is not a comprehensive list of reserved words, but it includes many of the strings that appear in SIP and SDP signaling.Show full document text