Internet DRAFT - draft-akhtar-sipping-3g-static-dictionary
draft-akhtar-sipping-3g-static-dictionary
SIPPING Haseeb Akhtar
Internet Draft Mohamed Khalil
Expires: March 09, 2007 Dave Brombal
Anthony Jones
Nortel
September 10, 2006
3G Wireless Support in the SIP/SDP Static Dictionary for
Signaling Compression (SigComp)
draft-akhtar-sipping-3g-static-dictionary-01.txt
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Copyright (C) The Internet Society (2006).
Abstract
While using SIGComp [4] based compression in SIP/SDP [5] [6], it is
imperative to have access to a static dictionary to be used on the
first SIP message that the compressor sends out. The session set up
time can be reduced significantly if the compression rate of the
first SIP message is considerably high.
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The existing static dictionary for SIP and SDP [2], however, does not
include some wireless specific data elements. This document
introduces these new data elements that are specific to various
wireless access technologies. These new data elements are part of the
first SIP message (i.e., originating SIP Invite) used to initiate a
session.
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Table of Contents
1. Introduction............................................... 3
2. Design considerations...................................... 3
3. 3G Data Elements........................................... 4
4. Binary representation of the 3G dictionary................. 4
5. Security Considerations.................................... 5
6. IANA Considerations........................................ 5
7. Acknowledgements........................................... 5
8. References................................................. 5
8.1 Normative References................................... 5
8.2 Informative References................................. 6
Authors' Addresses............................................ 6
Intellectual Property and Copyright Statements ............... 7
1. Introduction
While using SIGComp [3] based compression in SIP/SDP [5] [6], it is
imperative to have access to a static dictionary to be used on the
first SIP message that the compressor sends out. The session set up
time can be reduced significantly if the compression rate of the
first SIP message is considerably high.
The existing static dictionary for SIP and SDP [2], however, does not
include some wireless specific data elements. This document
introduces these new data elements that are specific to various
wireless access technologies. These new data elements are part of the
first SIP message (i.e., originating SIP Invite) used to initiate a
session.
2. Design considerations
The static 3G SIP/SDP dictionary is a collection of well-known
strings related to 3rd generation wireless access technologies that
appear in most of the SIP and SDP messages.
The new data elements should be inclusive of the existing SIP/SDP
static data dictionary specified by [2].
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3. 3G Data Elements
The following SIP data elements have been introduced by this
proposal.
- 'P-Preferred-Identity'
- 'P-Access-Network-Info'
- 'Require: sec-agree, precondition'
- 'Max-Forwards: 70'
- 'Supported: 100 rel'
- 'Spi:s'
- 'Port:c='
- 'Port:s='
The following SDP data elements have been introduced by this
proposal.
- 'Content-Type: application/SDP'
- 'a=des:qos mandatory, local sendrecv'
- 'a=des:qos none, local sendrecv'
- 'a=inactive'
4. Binary representation of the 3G dictionary
This section lists the SIP and SDP input strings used in generating the
dictionary, as well as a priority value, the offset of the string in
the generated dictionary, the length of the string, and one or more
references into the referenced documents that motivate the presence of
this string. Note that the notation "[CRLF]" stands for a sequence of
two bytes with the values 0x0d and 0x0a, respectively. The priority
value is used for determining the position of the string in the
dictionary. Lower priority values (higher priorities) cause the string
to occur at a later position in the dictionary, making it more
efficient to reference the string in certain compression algorithms.
Hence, lower priority values were assigned to strings more likely to
occur.
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The following the list of strings with their associated priority,
offset, length and reference sections.
Offset Reference
------ ---------
String Priority Length
------ -------- ------
"[CRLF]Max-Forwards: 70" 1 TBD 11 [3] 7.2.3.1
"[CRLF]P-Preferred-Identity" 1 TBD 16 [3] 7.2.3.1
"[CRLF]P-Access-Network-Info" 1 TBD 17 [3] 7.2.3.1
"[CRLF]Require: sec-agree, precondition" 1 TBD 22 [3] 7.2.3.1
"[CRLF]Supported: 100 rel" 1 TBD 14 [3] 7.2.3.1
"[CRLF]Spi:s" 1 TBD 7 [3] 7.2.3.1
"[CRLF]Port:c=" 1 TBD 9 [3] 7.2.3.1
"[CRLF]Port:s=" 1 TBD 9 [3] 7.2.3.1
"[CRLF]Content-Type: application/SDP" 1 TBD 1F [3] 7.2.3.1
"[CRLF]a=des:qos mandatory, local sendrecv" 1 TBD 25 [3] 7.2.3.1
"[CRLF]a=des:qos none, remote sendrecv" 1 TBD 21 [3] 7.2.3.1
"[CRLF]a=inactive" 1 TBD C [3] 7.2.3.1
5. Security Considerations
The security considerations of [2] apply. This proposal does not
introduce any known additional security risk.
6. IANA Considerations
None.
7. Acknowledgements
8. References
8.1 Normative References
[1] Bradner, S., "Key words for use in RFCs to indicate requirement
levels", BCP 14, RFC 2119, March 1997.
[2] Garcia-Martin, M., Borman, C., Ott, J., Price, R. and A. B.
Roach, "The Session Initiation Protocol (SIP) and Session
Description Protocol(SDP) Static Dictionary for Signaling
Compression (SigComp)", RFC 3485, February 2003.
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[3] "Signaling Flows for the IP Multimedia Call Control based on
Session Initiated Protocol (SIP) and Session Description
Protocol (SDP)", 3GPP TS 24.228 v5.14.0, December 2005.
8.2 Informative References
[4] Price, R., Bormann, C., Christoffersson, J., Hannu, H., Liu, Z.
and J. Rosenberg, "Signaling Compression (SigComp)", RFC 3320,
January 2003.
[5] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A.,
Peterson, J., Sparks, R., Handley, M. and E. Schooler, "SIP:
Session Initiation Protocol", RFC 3261, June 2002.
[6] Handley, M., Jacobson, V. and C. Perkins, "SDP: Session
Description Protocol", RFC 2327, April 1998.
[7] Garcia-Martin, M., "3rd-Generation Partnership Project (3GPP)
Release 5 requirements on the Session Initiation Protocol
(SIP)", Work in Progress.
Authors' Addresses
Haseeb Akhtar
Nortel
2221 Lakeside Blvd
Richardson, TX 75082
US
Email: haseebak@nortel.com
Mohamed Khalil
Nortel Networks
2221 Lakeside Blvd
Richardson, TX 75082
US
Email: mkhalil@nortel.com
Dave Brombal
Nortel
2221 Lakeside Blvd
Richardson, TX 75082
US
Email: davidb@nortel.com
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Anthony Jones
Nortel
3500 Carling Avenue
Ottawa, Ontario
K2H 8E9
Canada
Email: ajones@nortel.com
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