MIP4                                                           V. Sastry
Internet-Draft                                       Samsung Electronics
Intended status: Standards Track                                K. Leung
Expires: July 19, 2007                                          A. Patel
                                                           Cisco Systems
                                                        January 15, 2007


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

Status of this Memo

   By submitting this Internet-Draft, each author represents that any
   applicable patent or other IPR claims of which he or she is aware
   have been or will be disclosed, and any of which he or she becomes
   aware will be disclosed, in accordance with Section 6 of BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
   other groups may also distribute working documents as Internet-
   Drafts.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/ietf/1id-abstracts.txt.

   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html.

   This Internet-Draft will expire on July 19, 2007.

Copyright Notice

   Copyright (C) The IETF Trust (2007).












Sastry, et al.            Expires July 19, 2007                 [Page 1]


Internet-Draft    Mobile IPv4 Message String Extension      January 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 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































Sastry, et al.            Expires July 19, 2007                 [Page 2]


Internet-Draft    Mobile IPv4 Message String Extension      January 2007


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. 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.

   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, 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.  For
   example, a string like "registration failed : Prepaid Quota for the
   user is exhausted" can give a human readable description of the
   result of Mobile IP registration.



























Sastry, et al.            Expires July 19, 2007                 [Page 3]


Internet-Draft    Mobile IPv4 Message String Extension      January 2007


2.  Terminology

   The 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 [RFC2119].














































Sastry, et al.            Expires July 19, 2007                 [Page 4]


Internet-Draft    Mobile IPv4 Message String Extension      January 2007


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.  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 of the Text
      field.

   Sub-Type:

      1:

         Extension comes from the Home Agent

      2:

         Extension 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
      that the message contain UTF-8 encoded 10646 [RFC3629] characters.
      The number of octets in the 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.)





Sastry, et al.            Expires July 19, 2007                 [Page 5]


Internet-Draft    Mobile IPv4 Message String Extension      January 2007


      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.















































Sastry, et al.            Expires July 19, 2007                 [Page 6]


Internet-Draft    Mobile IPv4 Message String Extension      January 2007


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.  The usage of Text field of the Message String
   Extension is implementation dependent.  For example, the 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.

   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.example.com to update balance".  The Mobile Node
   could display this on the user interface.  As a 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.example.com".
   The Mobile Node could display this on the user interface thus
   confirming successful creation of binding on Home Agent.


























Sastry, et al.            Expires July 19, 2007                 [Page 7]


Internet-Draft    Mobile IPv4 Message String Extension      January 2007


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 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.





































Sastry, et al.            Expires July 19, 2007                 [Page 8]


Internet-Draft    Mobile IPv4 Message String Extension      January 2007


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 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.
   Similar to the procedures specified for Mobile IPv4 [RFC3344] number
   spaces, future allocations from this number space require expert
   review [RFC2434].



































Sastry, et al.            Expires July 19, 2007                 [Page 9]


Internet-Draft    Mobile IPv4 Message String Extension      January 2007


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.














































Sastry, et al.            Expires July 19, 2007                [Page 10]


Internet-Draft    Mobile IPv4 Message String Extension      January 2007


8.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in 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 2434,
              October 1998.

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

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





































Sastry, et al.            Expires July 19, 2007                [Page 11]


Internet-Draft    Mobile IPv4 Message String Extension      January 2007


Authors' Addresses

   Venkateshwara Sastry
   Samsung Electronics
   Bagmane Lake View, 'Block -B'
   66/1, Bagmane Tech Park, Byrasandra,
   C. V. Raman Nagar
   Bangalpre  560093
   India

   Phone: +91-80-41819999
   Email: 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



















Sastry, et al.            Expires July 19, 2007                [Page 12]


Internet-Draft    Mobile IPv4 Message String Extension      January 2007


Full Copyright Statement

   Copyright (C) The IETF Trust (2007).

   This document is subject to the rights, licenses and restrictions
   contained in BCP 78, and except as set forth therein, the authors
   retain all their rights.

   This document and the information contained herein are provided on an
   "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
   OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND
   THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS
   OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
   THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
   WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.


Intellectual Property

   The IETF takes no position regarding the validity or scope of any
   Intellectual Property Rights or other rights that might be claimed to
   pertain to the implementation or use of the technology described in
   this document or the extent to which any license under such rights
   might or might not be available; nor does it represent that it has
   made any independent effort to identify any such rights.  Information
   on the procedures with respect to rights in RFC documents can be
   found in BCP 78 and BCP 79.

   Copies of IPR disclosures made to the IETF Secretariat and any
   assurances of licenses to be made available, or the result of an
   attempt made to obtain a general license or permission for the use of
   such proprietary rights by implementers or users of this
   specification can be obtained from the IETF on-line IPR repository at
   http://www.ietf.org/ipr.

   The IETF invites any interested party to bring to its attention any
   copyrights, patents or patent applications, or other proprietary
   rights that may cover technology that may be required to implement
   this standard.  Please address the information to the IETF at
   ietf-ipr@ietf.org.


Acknowledgment

   Funding for the RFC Editor function is provided by the IETF
   Administrative Support Activity (IASA).





Sastry, et al.            Expires July 19, 2007                [Page 13]