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Versions: 00 01 02 03 05 06 07                                          
Internet Engineering Task Force         Mohamed M.Khalil, Nortel Networks
INTERNET-DRAFT                          Raja Narayanan, nVisible Networks
<draft-ietf-mobileip-mier-07.txt>       Haseeb Akhtar, Nortel Networks
Date: July, 2001,                      Emad Qaddoura, Nortel Networks
Expires: Jan, 2002




               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
     Task Force (IETF), its areas, and its working groups.  Note that
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     Drafts.

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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

     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 [Bradner97].

     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  two structures for Mobile IP
    extensions to be carried in the Mobile IP control messages.
    Since the new extension structures will cause an efficient
    usage of the extension type space, it is strongly recommended
    that all the new proposals for the Mobile IP WG that have new
    extensions SHOULD follow this format.












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2.2.1 Long Extension Format

   This format is applicable for non-skippable extensions which carry
   information more than 256 bytes. It should be applicable to any future
   standardization which consider non-skippable extensions which accommodate
   up to 64 KBytes of data.

      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 Long Extension consists
     of the following fields:


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


    Two bytes for the length field is suggested to enable providing a
    sufficiently large space for the extension data (maximum 64Kbytes).




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2.2.2 Short Extension Format

    This format is backward compatible with the skippable extensions
    as it is defined in [Perkins96]. Also, it applicable for extensions
    which doe not require more than 256 bytes of data.

      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   |    Data ....
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

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


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

    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 8-bit unsigned integer. Length of the extension, in octets,
           excluding the extension Type and the extension Length fields.
           This field MUST be set to 1 plus the total length of the
           data field.


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

3.0 Acknowledgements

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

4.0 References

    [Bradner97]  Bradner, S., "Key words for use in RFCs to Indicate
    Requirement Levels", BCP 14, RFC 2119, March 1997.

    [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 extensions' structure.

 A.1 General 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  General 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      |   Length      |   Sub-Type    | 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 General Session Key Extension

   This section  defines a general purpose security association
   extension which carries 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
     nVisible Networks.                    Nortel Networks Inc.
     4716 Winter Park Dr,                      2201 Lakeside Blvd
     Richardson, TX-75082                    Richardson, TX 75082-4399

     Phone: Ph: 1 + 214 684 4905             Phone: +1 972 684-8850
     E-mail: raja@nvisiblenetworks.com         E-mail: haseeb@nortelnetworks.com









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