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Versions: 00 01 02 03 05 06 07                                          
Internet Engineering Task Force                       Mohamed M.Khalil
INTERNET-DRAFT                                        Raja Narayanan
<draft-ietf-mobileip-mier-00.txt>                     Haseeb Akhtar
Date: Dec, 1999                                       Emad Qaddoura
Expires: May, 2000                                    Nortel Networks




               Mobile IP Extensions Rationalization (MIER)



Status of this memo

     This document is an Internet-Draft and is in full conformance
     with all provisions of Section 10 of RFC2026.

     Internet-Drafts are working documents of the Internet Engineering
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     Drafts.

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     The list of current Internet-Drafts can be accessed at
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Abstract

    It is in the interest of the Mobile IP WG to conserve the
    usage of the type field since we see many drafts proposing
    new extensions for Mobile IP. Therefore there is a real
    need to find ways to limit the usage of the type field in the
    extensions structure. MIER describes a new extension
    structure to Mobile IP to make the extensions far more
    extensible.

1.0 Introduction

    The type field in the Mobile IP extension structure can support
    upto 255 (skippable and not skippable) uniquely identifiable
    extensions. With new developments/additions to Mobile IP
    there is a strong possibility that the available space will
    run out.

    Mobile IP Extensions Rationalization (MIER) describes a
    new extension structure to solve this problem. MIER strategy
    is to initially aggregate certain types of extensions (e.g,
    NAI) and sub types to identify the precise extension (example
    MN/User NAI, HA NAI etc). This will greatly reduce the usage
    of the type field.

    MIER proposal is a natural evolution to the existing extension
    structure. It does not impact extensions that have been already
    defined.


   1.1 Terminology

   SA - Security Association [Perkins96]

   MN - Mobile Node [Perkins96]

   HA - Home Agent [Perkins96]

   FA - Foreign Agent [Perkins96]

   AAA - Authentication, Authorization, and Accounting.

   SPI - Security Parameters Index is a 32 bit number to index a SA
         in a database [Perkins96].








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2.0 Mobile IP Extension formats

    The extension structure proposed in this draft [Sec 2.2] is
    applicable to new extensions that are proposed to enhance
    Mobile IP. It does not apply to the extensions that have already
    been defined and standardised.

2.1 Existing Mobile IP Extension format

   According to [Perkins96] : Mobile IP defines a general Extension
   mechanism to allow optional information to be carried by Mobile
   IP control messages.  Each of these Extensions is encoded in the
   following Type-Length-Value format:

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

      Type     Indicates the particular type of Extension.

      Length   Indicates the length (in bytes) of the data field within
               this Extension.  The length does NOT include the Type and
               Length bytes.

      Data     The particular data associated with this Extension.  This
               field may be zero or more bytes in length.  The format
               and length of the data field is determined by the type
               and length fields.



2.2 New Mobile IP Extension format

    This draft proposes the following structure for Mobile IP
    extensions to be carried in the Mobile IP control messages.

     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      |   Sub-Type    |             Length            |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                           Data      .....
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


     The proposed general structure of the Generic Extension consists
     of the following fields:





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    Type   is the type which describe a collection of extensions which
           has a common data type (see A.1, A.2, A.3).

    Sub-Type  is a unique number given to each member in the
              aggregated type.  Sub-Type values between of 200 through
              255 are reserved for future use and standardization.

    Length indicates the length (in bytes) of the data field within
           this Extension. It does NOT include the Type, Length
           and Sub-Type bytes.

    Data   is the data associated with this extension. This data MAY
           be represented in many ways (see A.1, A.2, A.3)


    Two bytes for the length field is suggested to enable providing a
    sufficiently large space for the extension data.

    Since this extension structure will cause an efficient usage of
    the extension type space, it is mandatory that all the new
    proposals for the Mobile IP WG that have new extensions MUST
    follow this format unless there is an overwhelming reason
    not to do so.



3.0 Acknowledgements

    The authors would like to acknowledge Basavaraj Patil, Pat
    Calhoun, Neil Justusson and C. Perkins for their input in
    writing this draft.


4.0 References

    [Calhoun99a] Calhoun, Perkins, "Mobile IP Network Access
    Identifier Extension", draft-ietf-mobileip-mn-nai-05.txt

    [Perkins96] Perkins, "IP mobility Support", RFC 2002, Oct 96

    [Perkins99] Perkins, "Mobile IP Challenge/Response Extensions"
    draft-ietf-mobileip-challenge-06.txt

    [Bradner97] Bradner, "Key words for use in RFCs to Indicate
    Requirement Levels", RFC 2119, Mar 97



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A APPENDIX

  The following are some exmples where we could use the concept
  of the proposed extension's structure.

 A.1 Generic Authentication Extension

    This section defines a generic authentication extensions.

     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      |   Sub-Type    |              Length           |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                               SPI                             |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                       Authenticator   .....
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

    Type            Authentication Extension type (TBD)

    Sub-Type        this field describes the type of the entity which
                    owns the Authentication Extension. The following
                    types are defined:
                    1     MN-AAA Authentication Extension

    length          The length of the Authenticator field.

    SPI             Security Parameters Index

    Authenticator   The variable length Authenticator field consists
                    random value of at least 128 bits.

A.2  Generic NAI Extension

    This section  defines a general purpose NAI extension for
    different types of entities such MN, HA, FA etc.

     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      |   Sub-Type    |             Length            |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                            NAI-INFO   .....
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

    Type           NAI Aggregate type (TBD)

    length         The length of the NAI-INFO field.




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    Sub-Type       this field describes the type of the entity which
                   owns the NAI. The following types are defined:
                   0     MN-NAI
                   1     FA-NAI
                   2     HA-NAI
                   3     Previous FA-NAI Extension


   NAI-INFO        Contains the NAI in a string format.

A.3 Generic Session Key Extension

   This section  defines a general purpose security association
   extension which carrries information necessary to establish security
   association between different entities in the Mobile IP model
   (e.g. MN-FA, FA-HA and MN-HA ).

     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      |   Sub-Type    |             Length            |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                              SPI1                             |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                              SPI2                             |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                     security information ...
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

    Type           Generic AA Key Extension (TBD)

    length         The length of the SA-INFO field.

    Sub-Type       defines the type of entity which owns the key
                   address:
                   0     MN-HA Key Extension
                   1     MN-FA Key Extension
                   2     FA-HA Key Extension


     SPI1          A 32-bit opaque value, indicating the SPI that the
                   mobile node must use to determine the algorithm to use
                   for recovering the security information.


     SPI2          A 32-bit opaque value, which the mobile node MUST use
                   to index all the necessary information recovered from
                   the FA security information after it is decoded.

     Security Information
                   The necessary information (including the
                   key, algorithm etc) required by the mobile node
                   to create a Mobility Security Assocation between
                   itself and another entity such as HA and FA.

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Author Information:


     Mohamed Khalil                          Emad Qaddoura
     Nortel Networks Inc.                    Nortel Networks Inc.
     2201 Lakeside Blvd                      2201 Lakeside Blvd
     Richardson, TX 75082-4399               Richardson, TX 75082-4399

     Phone: +1 972 685-0564                  Phone: +1 972 684-2705
     E-mail: mkhalil@nortelnetworks.com      E-mail: emadq@nortelnetworks.com

     Raja Narayanan                          Haseeb Akhtar
     Nortel Networks Inc.                    Nortel Networks Inc.
     2201 Lakeside Blvd                      2201 Lakeside Blvd
     Richardson, TX 75082-4399               Richardson, TX 75082-4399

     Phone: +1 972 684-5707                  Phone: +1 972 684-8850
     E-mail: raja@nortelnetworks.com         E-mail: haseeb@nortelnetworks.com


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