Network Working Group
MIP4                                                           V. Sastry
Internet-Draft                                                  K. Leung                                       Samsung Electronics
Intended status: Standards Track                                A. Patel                                K. Leung
Expires: March 18, July 19, 2007                                          A. Patel
                                                           Cisco Systems
                                                      September 14, 2006
                                                        January 15, 2007

                  Mobile IPv4 Message String Extension
               draft-ietf-mip4-message-string-ext-01.txt
               draft-ietf-mip4-message-string-ext-02.txt

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Copyright Notice

   Copyright (C) The Internet Society (2006). IETF Trust (2007).

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. messages.  This extension carries a text string
   that is intended for the user of the Mobile Node.

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.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 10
   8.  Normative References . . . . . . . . . . . . . . . . . . . . . 11
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12
   Intellectual Property and Copyright Statements . . . . . . . . . . 13

1.  Introduction

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

   Content

   The content of the text string in this extension and its usage by the
   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
   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 a registration
   failure reason, or give 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  For
   example, a string like "registration failed : Prepaid Quota for the
   user is
   exhausted", "registration success : Unauthorized Access is
   Prohibited", exhausted" can give a human readable description of the
   result of Mobile IP registration.

2.  Terminology

   The keywords key words "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. 2119 [RFC2119].

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 integer.  Length of the extension, in bytes,
      excluding the extension Type and the extension Length fields.
      This field MUST be set to 1 plus the total length in octets of the Text
      field.

   Sub-Type:

      1:

         Extension is added by comes from the Home Agent

      2:

         Extension is added by comes from the Foreign Agent

   Text:

      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 RECOMMENDED
      that the message contain UTF-8 encoded 10646 [RFC3629] characters.
      The number of octets in the UTF-8 encoded representation of the message
      is always exactly the value of the Length field minus one.  (In
      the UTF-8 case, the number of unicode characters represented by
      this octet sequence may be smaller than the number of octets.)
      Other encoding methods than UTF-8 may only be used in closed
      environments where it can be guaranteed that both message sender
      and receiver know the exact encoding method, and know that the
      encoding method is different from UTF-8.

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 the Home Agent or
   Foreign Agent or both can add the Message String Extension to
   registration messages.  Usage  The usage of Text field of the Message String
   Extension is implementation dependent.  For example, this the message can
   be displayed on the Mobile Node's user interface, logged 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,

   The Mobile Node may throttle how often the user is notified of the
   message (either via display on user interface, logging, etc.)  For
   example, the 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 www.paymore.example.com to update balance".  The Mobile Node
   could display this on the user interface.  As a response response, the user of
   the Mobile Node may take the required action to update the prepaid
   account and retry the registration process.  The Home Agent may
   accept this Registration Request and attach a Message String
   Extension with the text "Welcome to www.serviceprovider.com". www.serviceprovider.example.com".
   The Mobile Node could display this on the user interface thus
   confirming successful creation of binding on Home Agent.

5.  Security Considerations

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

   If the extension is added by the Home Agent (extension with subtype
   1) to a 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 a 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.

6.  IANA Considerations

   This specification reserves one number for the Message String
   Extension in 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 suggested 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
   Similar to the procedures specified for Mobile IPv4 [RFC3344] number
   spaces, future allocations from this number space by IANA actions. require expert
   review [RFC2434].

7.  Acknowledgements

   The authors would like to thank Avi Lior, Curtis Provost and Henrik
   Levkowetz for their useful comments on an eariler version of this
   document.

8.  Normative References

   [FA-ERR]   Perkins, C., "Foreign Agent Error Extension

   [RFC2119]  Bradner, S., "Key words for Mobile
              IPv4", draft-ietf-mip4-faerr-02.txt (work use in progress),
              September  2005.

   [RFC2865]  Rigney, C., Willens, S., Rubens, A., and W. Simpson,
              "Remote Authentication Dial In User Service (RADIUS)", RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC2434]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", BCP 26, RFC 2865, June 2000. 2434,
              October 1998.

   [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.

   [RFC3629]  Yergeau, F., "UTF-8, a transformation format of ISO
              10646", STD 63, RFC 3629, November 2003.

Authors' Addresses

   Venkateshwara Sastry
   Cisco Systems
   Akkithimanahalli, O'Shaugnessy Road
   Bangalore  560085
   Samsung Electronics
   Bagmane Lake View, 'Block -B'
   66/1, Bagmane Tech Park, Byrasandra,
   C. V. Raman Nagar
   Bangalpre  560093
   India

   Phone: +91 80-51033757 +91-80-41819999
   Email: vsastry@cisco.com venkat.s@samsung.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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   Copyright (C) The Internet Society (2006). IETF Trust (2007).

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