Internet DRAFT - draft-sastry-mip4-string-extension

draft-sastry-mip4-string-extension






Network Working Group                                          V. Sastry
Internet-Draft                                                  K. Leung
Expires: April 7, 2006                                          A. Patel
                                                           Cisco Systems
                                                        October 04, 2005


                  Mobile IPv4 Message String Extension
               draft-sastry-mip4-string-extension-03.txt

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Copyright Notice

   Copyright (C) The Internet Society (2005).

Abstract

   This document specifies a new extension for use in Mobile IPv4.  This
   extension can be added by the Home Agent and the Foreign Agent to
   Registration Reply message.  This extension carries a text string
   that is intended for the user of the Mobile Node.






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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  4
   3.  Mobile IPv4 Message String Extension Format  . . . . . . . . .  5
   4.  Operation and Use of the Message String Extension  . . . . . .  7
   5.  Security Considerations  . . . . . . . . . . . . . . . . . . .  8
   6.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . .  9
   7.  Normative References . . . . . . . . . . . . . . . . . . . . .  9
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10
   Intellectual Property and Copyright Statements . . . . . . . . . . 11








































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1.  Introduction

   This document specifies a new skippable extension that can be added
   by Foreign Agent and Home Agent in registration message targeted for
   the Mobile Node.  Such a message may be either a Registration Reply
   or Registration Revocation (i.e. collocated Care-of Address mode).
   For the Registration Reply message, this extension can be added
   regardless of whether the registration has succeeded or failed.

   Content of the text string in this extension and its usage by Mobile
   Node is implementation specific.  The text string in this extension
   is intended for the user of the Mobile Node.  For example, this
   message can be displayed on the Mobile Node's user interface, logged
   or handled in any other implementation dependent way, depending on
   the form of the Mobile Node.

   Typical contents of the text string will indicate registration
   failure reason, or a welcome message on successful registration.
   This is important as the failure reason code gives very limited
   information for interpretation by the user of the Mobile Node.  A
   string like "registration failed : Prepaid Quota for the user is
   exhausted", "registration success : Unauthorized Access is
   Prohibited", can give a human readable description of the result of
   Mobile IP registration.



























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2.  Terminology

   The keywords "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119.














































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3.  Mobile IPv4 Message String Extension Format

   The Message String Extension conforms to the Short Extension format
   specified for Mobile IPv4 [RFC3344].  The Message String Extension is
   a skippable extension.


        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |     Type      |   Length      |    Sub-Type   |    Text ....
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   Type:



      To be assigned by IANA.  An 8-bit identifier of the type mobility
      option.

   Length:



      8-bit unsigned integer, equaling 1 plus the length in octets of
      the Text

   Sub-Type:



      1:



         Extension is added by Home Agent



      2:



         Extension is added by Foreign Agent

   Text:




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      The Text field is one or more octets, and its contents are
      implementation dependent.  It is intended to be human readable,
      and MUST NOT affect operation of the protocol.  It is recommended
      that the message contain UTF-8 encoded 10646 [RFC2279] characters.













































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4.  Operation and Use of the Message String Extension

   The Message String Extension is only valid for use within Mobile IPv4
   Registration Reply and Registration Revocation messages.  The Message
   String Extension is a skippable extension.  Either Home Agent or
   Foreign Agent or both can add Message String Extension to
   registration messages.  Usage of Text field of the Message String
   Extension is implementation dependent.  For example, this message can
   be displayed on the Mobile Node's user interface, logged or handled
   in an implementation dependent way, depending on the form of the
   Mobile Node.

   Home Agent or Foreign Agent or both, MAY add the extension to each
   registration message to a Mobile Node.  However, Mobile Node may
   throttle how often the user is notified of the message (either via
   display on user interface, logging, etc.)  For example, Home Agent
   may reject the first Registration Request due to prepaid quota for
   the user is reached and may attach a Message String Extension with
   the text "Prepaid quota reached.  Please contact www.paymore.com to
   update balance".  Mobile Node could display this on the user
   interface.  As a response user of the Mobile Node may take the
   required action to update the prepaid account and retry the
   registration process.  Home Agent may accept this Registration
   Request and attach a Message String Extension with the text "Welcome
   to www.serviceprovider.com".  Mobile Node could display this on the
   user interface thus confirming successful creation of binding on Home
   Agent.
























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5.  Security Considerations

   Message String Extension can be added by Home Agent or Foreign Agent
   or both.

   If the extension is added by the Home Agent (extension with subtype
   1) to Registration Reply or Registration Revocation message, it MUST
   appear before Mobile-Home Authentication Extension [RFC3344].  If the
   the Mobile Node cannot understand this extension, it should be
   skipped.

   If the extension is added by the Foreign Agent (extension with
   subtype 2) to Registration Reply message, it MUST appear after
   Mobile-Home Authentication Extension [RFC3344] whenever present.
   Also the extension MUST appear before the Mobile-Foreign
   Authentication Extension whenever present.  If Mobile Node cannot
   understand this extension, it should be skipped.


































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6.  IANA Considerations

   This specification reserves one number for the Message String
   Extension Section 3 from the space of numbers for skippable mobility
   extensions (i.e., 128-255) defined for Mobile IPv4 [RFC3344] at
   http://www.iana.org/assignments/mobileip-numbers.

   The value 145 is recommended for this extension.

   This specification also creates a new subtype space for the type
   number of this extension.  The subtype values 1 and 2 are defined in
   this specification.  The subtype value 1 is reserved for use by Home
   Agent and subtype value 2 is reserved for use by Foreign Agent.
   Other values can be allocated from this number space by IANA actions.

7.  Normative References

   [FA-ERR]   Perkins, C., "Foreign Agent Error Extension for Mobile
              IPv4", draft-ietf-mip4-faerr-02.txt (work in progress),
              September  2005.

   [RFC2279]  Yergeau, F., "UTF-8, a transformation format of ISO
              10646", RFC 2279, January 1998.

   [RFC2865]  Rigney, C., Willens, S., Rubens, A., and W. Simpson,
              "Remote Authentication Dial In User Service (RADIUS)",
              RFC 2865, June 2000.

   [RFC3344]  Perkins, C., "IP Mobility Support for IPv4", RFC 3344,
              August 2002.

   [RFC3543]  Glass, S. and M. Chandra, "Registration Revocation in
              Mobile IPv4", RFC 3543, August 2003.


















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Authors' Addresses

   Venkateshwara Sastry
   Cisco Systems
   Akkithimanahalli, O'Shaugnessy Road
   Bangalore  560085
   India

   Phone: +91 80-51033757
   Email: vsastry@cisco.com


   Kent Leung
   Cisco Systems
   170 W. Tasman Drive
   San Jose, CA  95134
   US

   Phone: +1 408-526-5030
   Email: kleung@cisco.com


   Alpesh Patel
   Cisco Systems
   170 W. Tasman Drive
   San Jose, CA  95134
   US

   Phone: +1 408-853-9580
   Email: alpesh@cisco.com





















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