IPv6 Preferred Address Format
-----------------------------

Yakov Rekhter
T. J. Watson Research Center, IBM Corp.
(e-mail: yakov@watson.ibm.com)



Foil 1.
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  Observations:

    - Need a routable system that can support a very large
      number of hosts

    - Use information aggregation (abstraction) for scalable
      routing

    - Hierarchical routing

    - Addresses congruent to topology:

      - address assignment as a function of topology

        or

      - topology as a function of address assignment


Foil 2.
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  Overall Format Structure:

    +-------------------------------+
    |        Format Prefix          |
    +-------------------------------+
    | Registry Identifier Component |
    +-------------------------------+
    |  Registry-Specific Component  |
    +-------------------------------+
    |  Provider-Specific Component  |
    +-------------------------------+
    | Subscriber-Specific Component |
    +-------------------------------+

  Each component is a variable length field

    - suggested ranges


Foil 3.
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  Registry Identifier

    - Internet Registry (IR) as the principal registry

      - IANA as the IR

    - Blocks of addresses given to the Regional Registries

      - Registry Identifier identifies individual blocks


Foil 4.
------

  Registry-Specific Component

    - Identifies address blocks allocated by the Regional Registries

    - Suggested range between 1 and 3 octets

      - accommodate a wide range of demands for address blocks

      - leave between 12 and 14 octets for Provider-Specific
        component and Subscriber-Specific component


Foil 5.
-------

  Provider-Specific Component

    - Identifies address blocks allocated by Providers

    - Suggested range between 1 and 4 octets

      - accommodate a wide range of demands for address blocks

      - leave between 8 and 13 octets for the Subscriber-Specific
        component


Foil 6.
-------

  Subscriber-Specific Component

    - Up to individual subscribers

    - Recommend to leave at least 7 octets

      - Alternatives suggested by the document leave 8 to 13 octets


Foil 7.
-------

  Provider-Independent Addresses

    - Each Registry has a block of addresses for provider-independent
      address allocation

    - Use of provider-independent addresses has negative impact on
      the scalability of the routing system

      - don't reflect topology


Foil 8.
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  National Registries

    - Regional Registries allocate to National Registries

    - Optional

    - Assumes relatively small number of National Registries