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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Copyright Statement

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