New IPv6 Allocation Policies Ratified

Member Services memsvcs at arin.net
Mon Jul 29 15:57:02 EDT 2002



The following new policy has been ratified in the ARIN
region and will be implemented on August 1, 2002:

  Policy 2001-4: Modification to the IPv6 Allocation Policies

  The three RIRs have compiled the "IPv6 Address Allocation and
  Assignment Policy" document dated June 26, 2002, using feedback
  received from the RIR communities since the publishing of the
  provisional IPv6 document in 1999. In the interest of maintaining
  IPv6 policies that are global in scope, ARIN accepts the document
  with language on initial allocations as amended following the
  APNIC 13 and ARIN IX Public Policy Meetings.

The full text of the "IPv6 Address Allocation and Assignment
Policy" document can be viewed below.  This new policy text
and accompanying request templates will be posted on the ARIN
website on August 1, 2002.

This policy replaces ARIN's existing IPv6 allocation policies
and was created in accordance with ARIN's Internet Resource
Policy Evaluation Process which can be viewed here:

  http://www.arin.net/policy/ipep.html


Member Services
American Registry for Internet Numbers (ARIN)


##### * #####

The following modifications to this document have been made
since its final posting on June 26, 2002:

  * Duplicate word "Assignment" removed from title
  * Page numbers removed
  * Editorial comment regarding change status of
    definitions removed

##### * #####


         IPv6 Address Allocation and Assignment Policy
                               June, 26 2002


Status of this Memo

   This document was developed through joint discussions among the
   APNIC, ARIN and RIPE communities.

Abstract

   This document defines registry policies for the assignment and
   allocation of globally-unique IPv6 addresses to ISPs and other
   organizations.  This document obsoletes the "Provisional IPv6
   assignment and allocation policy document".

   This document was developed jointly by the communities of APNIC,
   ARIN, and RIPE.

   Contents

   Status of this Memo

   1.  Introduction
      1.1.  Overview

   2.  Definitions
      2.1.  Internet Registry (IR)
      2.2.  Regional Internet Registry (RIR)
      2.3.  National Internet Registry (NIR)
      2.4.  Local Internet Registry (LIR)
      2.5.  Allocate
      2.6.  Assign
      2.7.  Utilization
      2.8.  HD-Ratio
      2.9.  End site

   3.  Goals of IPv6 address space management
      3.1.  Goals
      3.2.  Uniqueness
      3.3.  Registration
      3.4.  Aggregation
      3.5.  Conservation
      3.6.  Fairness
      3.7.  Minimized Overhead
      3.8.  Conflict of goals

   4.  IPv6 Policy Principles
      4.1.  Address space not to be considered property
      4.2.  Routability not guaranteed
      4.3.  Minimum Allocation
      4.4.  Consideration of IPv4 Infrastructure

   5.  Policies for allocations and assignments
      5.1.  Initial allocation
         5.1.1.  Initial allocation criteria
         5.1.2.  Initial allocation size
      5.2.  Subsequent allocation
         5.2.1.  Subsequent allocation criteria
         5.2.2.  Applied HD-Ratio
         5.2.3.  Subsequent Allocation Size
      5.3.  LIR-to-ISP allocation
      5.4.  Assignment
         5.4.1.  Assignment address space size
         5.4.2.  Assignment of multiple /48s to a single end site
         5.4.3.  Assignment to operator's infrastructure
      5.5.  Registration
      5.6.  Reverse lookup
      5.7.  Existing IPv6 address space holders

   6.  References

   7.  Appendix A: HD-Ratio

   8.  Appendix B: Background information
      8.1.  Background
      8.2.  Why a joint policy
      8.3.  The size of IPv6's address space
      8.4.  Acknowledgment

1.  Introduction


1.1.  Overview

   This document describes policies for the allocation and assignment of
   globally-unique Internet Protocol Version 6 (IPv6) address space.  It
   updates and obsoletes the existing Provisional IPv6 Policies in
   effect since 1999 [RIRv6-Policies].  Policies described in this
   document are are intended to be adopted by each registry.  However,
   adoption of this document does not preclude local variations in each
   region or area.

   [RFC2373, RFC2373bis] designate 2000::/3 to be global unicast address
   space that IANA may allocate to the RIRs.  In accordance with
   [RFC2928, RFC2373bis, IAB-Request], IANA has allocated initial ranges
   of global unicast IPv6 address space from the 2001::/16 address block
   to the existing RIRs.  This document concerns the initial and
   subsequent allocations of the 2000::/3 unicast address space, for
   which RIRs formulate allocation and assignment policies.  Because end
   sites will generally be given /48 assignments [RFC 3177, RIRs-
   on-48s], the particular emphasis of this document is on policies
   relating the bits within 2000::/3 to the left of the /48 boundary.
   However, since some end sites will receive /64 and /128 assignments,
   all bits to the left of /64 are in scope.

   This policy is considered to be an interim policy.  It will be
   reviewed in the future, subject to greater experience in the
   administration of IPv6.


2.  Definitions

   The following terms and their definitions are of particular
   importance to the understanding of the goals, environment, and
   policies described in this document.

   Responsibility for management of IPv6 address spaces is distributed
   globally in accordance with the hierarchical structure shown below.


                +--------+
                |  IANA  |
                +--------+
                    |
              +-----------+
              |           |
          +--------+  +--------+
          |   RIR  |  |   RIR  |  Regional Internet
          +--------+  +--------+  Registries (APNIC, ARIN, RIPE NCC,
              |           |       plus possible future RIRs)
              |           |
              |        +-----+
              |        | NIR |     National Internet
              |        +-----+     Registries (AP region)
              |           |
         +--------+   +--------+
         |LIR/ISP |   |LIR/ISP |   Local Internet
         +--------+   +--------+   Registries (ISPs)
              |           |
        +--------+        |
        |        |        |
    +-------+  +----+   +----+
    |EU(ISP)|  | EU |   | EU |     End users
    +-------+  +----+   +----+


2.1.  Internet Registry (IR)

   An Internet Registry (IR) is an organization that is responsible for
   distributing IP address space to its members or customers and for
   registering those distributions.  IRs are classified according to
   their primary function and territorial scope within the hierarchical
   structure depicted in the figure above.


2.2.  Regional Internet Registry (RIR)

   Regional Internet Registries (RIRs) are established and authorized by
   respective regional communities, and recognized by the IANA to serve
   and represent large geographical regions.  The primary role of RIRs
   is to manage and distribute public Internet address space within
   their respective regions.


2.3.  National Internet Registry (NIR)

   A National Internet Registry (NIR) primarily allocates address space
   to its members or constituents, which are generally LIRs organized at
   a national level.  NIRs exist mostly in the Asia Pacific region.


2.4.  Local Internet Registry (LIR)

   A Local Internet Registry (LIR) is an IR that primarily assigns
   address space to the users of the network services that it provides.
   LIRs are generally ISPs, whose customers are primarily end users and
   possibly other ISPs.


2.5.  Allocate

   To allocate means to distribute address space to IRs for the purpose
   of subsequent distribution by them.


2.6.  Assign

   To assign means to delegate address space to an ISP or end-user, for
   specific use within the Internet infrastructure they operate.
   Assignments must only be made for specific purposes documented by
   specific organizations and are not to be sub-assigned to other
   parties.


2.7.  Utilization

   Unlike IPv4, IPv6 is generally assigned to end sites in fixed amounts
   (/48).  The actual usage of addresses within each assignment will be
   quite low, when compared to IPv4 assignments.  In IPv6, "utilization"
   is only measured in terms of the bits to the left of the /48
   boundary.  In other words, utilization refers to the assignment of
   /48s to end sites, and not the number of addresses assigned within
   individual /48s at those end sites.

   Throughout this document, the term utilization refers to the
   allocation of /48s to end sites, and not the number of addresses
   assigned within individual /48s within those end sites.


2.8.  HD-Ratio

   The HD-Ratio is a way of measuring the efficiency of address
   assignment [RFC 3194].  It is an adaptation of the H-Ratio originally
   defined in [RFC1715] and is expressed as follows:

                     Log (number of allocated objects)
                HD = ------------------------------------------------
                     Log (maximum number of allocatable objects)

   where (in the case of this document) the objects are IPv6 site
   addresses (/48s) assigned from an IPv6 prefix of a given size.


2.9.  End site

   An end site is defined as an end user (subscriber) who has a business
   relationship with a service provider that involves:

    - that service provider assigning address space to the end user
    - that service provider providing transit service for the end user
      to other sites
    - that service provider carrying the end user's traffic.
    - that service provider advertising an aggregate prefix route that
      contains the end user's assignment


3.  Goals of IPv6 address space management


3.1.  Goals

   IPv6 address space is a public resource that must be managed in a
   prudent manner with regards to the long-term interests of the
   internet.  Responsible address space management involves balancing a
   set of sometimes competing goals.  The following are the goals
   relevant to IPv6 address policy.


3.2.  Uniqueness

   Every assignment and/or allocation of address space must guarantee
   uniqueness worldwide.  This is an absolute requirement for ensuring
   that every public host on the Internet can be uniquely identified.


3.3.  Registration

   Internet address space must be registered in a registry database
   accessible to appropriate members of the Internet community.  This is
   necessary to ensure the uniqueness of each Internet address and to
   provide reference information for Internet troubleshooting at all
   levels, ranging from all RIRs and IRs to end users.

   The goal of registration should be applied within the context of
   reasonable privacy considerations and applicable laws.


3.4.  Aggregation

   Wherever possible, address space should be distributed in a
   hierarchical manner, according to the topology of network
   infrastructure.  This is necessary to permit the aggregation of
   routing information by ISPs, and to limit the expansion of Internet
   routing tables.

   This goal is particularly important in IPv6 addressing, where the
   size of the total address pool creates significant implications for
   both internal and external routing.

   IPv6 address policies should seek to avoid fragmentation of address
   ranges.

   Further, RIRs should apply practices that maximize the potential for
   subsequent allocations to be made contiguous with past allocations
   currently held.  However, there can be no guarantee of contiguous
   allocation.


3.5.  Conservation

   Although IPv6 provides an extremely large pool of address space,
   address policies should avoid unnecessarily wasteful practices.
   Requests for address space should be supported by appropriate
   documentation and stockpiling of unused addresses should be avoided.


3.6.  Fairness

   All policies and practices relating to the use of public address
   space should apply fairly and equitably to all existing and potential
   members of the Internet community, regardless of their location,
   nationality, size or any other factor.


3.7.  Minimized Overhead

   It is desirable to minimize the overhead associated with obtaining
   address space.  Overhead includes the need to go back to RIRs for
   additional space too frequently, the overhead associated with
   managing address space that grows through a number of small
   successive incremental expansions rather than through fewer, but
   larger, expansions.


3.8.  Conflict of goals

   The goals described above will often conflict with each other, or
   with the needs of individual IRs or end users.  All IRs evaluating
   requests for allocations and assignments must make judgments, seeking
   to balance the needs of the applicant with the needs of the Internet
   community as a whole.

   In IPv6 address policy, the goal of aggregation is considered to be
   the most important.


4.  IPv6 Policy Principles

   To address the goals described in the previous section, the policies
   in this document discuss and follow the basic principles described
   below.


4.1.  Address space not to be considered property

   It is contrary to the goals of this document and is not in the
   interests of the Internet community as a whole for address space to
   be considered freehold property.

   The policies in this document are based upon the understanding that
   globally-unique IPv6 unicast address space is licensed for use rather
   than owned.  Specifically, IP addresses will be allocated and
   assigned on a license basis, with licenses subject to renewal on a
   periodic basis.  The granting of a license is subject to specific
   conditions applied at the start or renewal of the license.

   RIRs will generally renew licenses automatically, provided requesting
   organizations are making a good-faith effort at meeting the criteria
   under which they qualified for or were granted an allocation or
   assignment.  However, in those cases where a requesting organization
   is not using the address space as intended, or is showing bad faith
   in following through on the associated obligation, RIRs reserve the
   right to not renew the license.

   Note that when a license is renewed, the new license will be
   evaluated under and governed by the applicable IPv6 address policies
   in place at the time of renewal, which may differ from the policy in
   place at the time of the original allocation or assignment.


4.2.  Routability not guaranteed

   There is no guarantee that any address allocation or assignment will
   be globally routable.

   However, RIRs must apply procedures that reduce the possibility of
   fragmented address space which may lead to a loss of routability.


4.3.  Minimum Allocation

   RIRs will apply a minimum size for IPv6 allocations, to facilitate
   prefix-based filtering.

   The minimum allocation size for IPv6 address space is /32.


4.4.  Consideration of IPv4 Infrastructure

   Where an existing IPv4 service provider requests IPv6 space for
   eventual transition of existing services to IPv6, the number of
   present IPv4 customers may be used to justify a larger request than
   would be justified if based solely on the IPv6 infrastructure.


5.  Policies for allocations and assignments


5.1.  Initial allocation


5.1.1.  Initial allocation criteria

   To qualify for an initial allocation of IPv6 address space, an
   organization must:

   a) be an LIR;
   b) not be an end site;
   c) plan to provide IPv6 connectivity to organizations to which it
      will assign /48s, by advertising that connectivity through its
      single aggregated address allocation; and
   d) have a plan for making at least 200 /48 assignments to other
      organizations within two years.


5.1.2.  Initial allocation size

   Organizations that meet the initial allocation criteria are eligible
   to receive a minimum allocation of /32.

   Organizations may qualify for an initial allocation greater than /32
   by submitting documentation that reasonably justifies the request.
   If so, the allocation size will be based on the number of existing
   users and the extent of the organization's infrastructure.


5.2.  Subsequent allocation

   Organizations that hold an existing IPv6 allocation may receive a
   subsequent allocation in accordance with the following policies.


5.2.1.  Subsequent allocation criteria

   Subsequent allocation will be provided when an organization (ISP/LIR)
   satisfies the evaluation threshold of past address utilization in
   terms of the number of sites in units of /48 assignments.  The HD-
   Ratio [RFC 3194] is used to determine the utilization thresholds that
   justify the allocation of additional address as described below.


5.2.2.  Applied HD-Ratio

   The HD-Ratio value of 0.8 is adopted as indicating an acceptable
   address utilization for justifying the allocation of additional
   address space.  Appendix A provides a table showing the number of
   assignments that are necessary to achieve an acceptable utilization
   value for a given address block size.


5.2.3.  Subsequent Allocation Size

   When an organization has achieved an acceptable utilization for its
   allocated address space, it is immediately eligible to obtain an
   additional allocation that results in a doubling of the address space
   allocated to it.  Where possible, the allocation will be made from an
   adjacent address block, meaning that its existing allocation is
   extended by one bit to the left.

   If an organization needs more address space, it must provide
   documentation justifying its requirements for a two-year period.  The
   allocation made will be based on this requirement.


5.3.  LIR-to-ISP allocation

   There is no specific policy for an organization (LIR) to allocate
   address space to subordinate ISPs.  Each LIR organization may develop
   its own policy for subordinate ISPs to encourage optimum utilization
   of the total address block allocated to the LIR.  However, all /48
   assignments to end sites are required to be registered either by the
   LIR or its subordinate ISPs in such a way that the RIR/NIR can
   properly evaluate the HD-Ratio when a subsequent allocation becomes
   necessary.


5.4.  Assignment

   LIRs must make IPv6 assignments in accordance with the following
   provisions.


5.4.1.  Assignment address space size

   Assignments are to be made in accordance with the existing guidelines
   [RFC3177,RIRs-on-48], which are summarized here as:

    - /48 in the general case, except for very large subscribers
    - /64 when it is known that one and only one subnet is needed by
      design
    - /128 when it is absolutely known that one and only one device is
      connecting.

   RIRs/NIRs are not concerned about which address size an LIR/ISP
   actually assigns.  Accordingly, RIRs/NIRs will not request the
   detailed information on IPv6 user networks as they did in IPv4,
   except for the cases described in Section 4.4 and for the purposes of
   measuring utilization as defined in this document.


5.4.2.  Assignment of multiple /48s to a single end site

   When a single end site requires an additional /48 address block, it
   must request the assignment with documentation or materials that
   justify the request.  Requests for multiple or additional /48s will
   be processed and reviewed (i.e., evaluation of justification) at the
   RIR/NIR level.

   Note: There is no experience at the present time with the assignment
   of multiple /48s to the same end site.  Having the RIR review all
   such assignments is intended to be a temporary measure until some
   experience has been gained and some common policies can be developed.
   In addition, additional work at defining policies in this space will
   likely be carried out in the near future.


5.4.3.  Assignment to operator's infrastructure

   An organization (ISP/LIR) may assign a /48 per PoP as the service
   infrastructure of an IPv6 service operator.  Each assignment to a PoP
   is regarded as one assignment regardless of the number of users using
   the PoP.  A separate assignment can be obtained for the in-house
   operations of the operator.


5.5.  Registration

   When an organization holding an IPv6 address allocation makes IPv6
   address assignments, it must register assignment information in a
   database, accessible by RIRs as appropriate (information registered
   by an RIR/NIR may be replaced by a distributed database for
   registering address management information in future).  Information
   is registered in units of assigned /48 networks.  When more than a
   /48 is assigned to an organization, the assigning organization is
   responsible for ensuring that the address space is registered in an
   RIR/NIR database.

   RIR/NIRs will use registered data to calculate the HD-Ratio at the
   time of application for subsequent allocation and to check for
   changes in assignments over time.

   IRs shall maintain systems and practices that protect the security of
   personal and commercial information that is used in request
   evaluation, but which is not required for public registration.


5.6.  Reverse lookup

   When an RIR/NIR delegates IPv6 address space to an organization, it
   also delegates the responsibility to manage the reverse lookup zone
   that corresponds to the allocated IPv6 address space.  Each
   organization should properly manage its reverse lookup zone.  When
   making an address assignment, the organization must delegate to an
   assignee organization, upon request, the responsibility to manage the
   reverse lookup zone that corresponds to the assigned address.


5.7.  Existing IPv6 address space holders

   Organizations that received /35 IPv6 allocations under the previous
   IPv6 address policy [RIRv6-Policies] are immediately entitled to have
   their allocation expanded to a /32 address block, without providing
   justification, so long as they satisfy the criteria in Section 5.1.1.
   The /32 address block will contain the already allocated smaller
   address block (one or multiple /35 address blocks in many cases) that
   was already reserved by the RIR for a subsequent allocation to the
   organization.  Requests for additional space beyond the minimum /32
   size will be evaluated as discussed elsewhere in the document.



6.  References

   [RFC1715] "The H Ratio for Address Assignment Efficiency", C.
           Huitema.
                November 1994, RFC 1715.

   [IAB-Request] "Email from IAB to IANA",
           http://www.iab.org/iab/DOCUMENTS/IPv6addressspace.txt.

   [RFC2373] "IP Version 6 Addressing Architecture", R.  Hinden, S.
           Deering.  July 1998, RFC 2373.

   [RFC2373bis] draft-ietf-ipngwg-addr-arch-v3-07.txt.

   [RFC2928] "Initial IPv6 Sub-TLA ID Assignments", R.  Hinden, S.
           Deering, R.  Fink, T.  Hain.  September 2000, RFC 2928.

   [RFC3177] "IAB/IESG Recommendations on IPv6 Address".  IAB, IESG.
           September 2001, RFC 3177.

   [RFC3194] "The H-Density Ratio for Address Assignment Efficiency An
           Update on the H ratio", A.  Durand, C.  Huitema.  November
           2001, RFC 3194.

   [RIRs-on-48]
           http://www.arin.net/library/guidelines/ipv6_initial.html,


   [RIRv6-Policies]
           http://www.arin.net/regserv/ipv6/ipv6guidelines.html,
           http://www.ripe.net/ripe/docs/ripe-196.html,

http://www.apnic.net/docs/drafts/ipv6/ipv6-policy-280599.html.


7.  Appendix A: HD-Ratio

   The HD-Ratio is not intended to replace the traditional utilization
   measurement that ISPs perform with IPv4 today.  Indeed, the HD-Ratio
   still requires counting the number of assigned objects.  The primary
   value of the HD-Ratio is its usefulness at determining reasonable
   target utilization threshold values for an address space of a given
   size.  This document uses the HD-Ratio to determine the thresholds at
   which a given allocation has achieved an acceptable level of
   utilization and the assignment of additional address space becomes
   justified.

   The utilization threshold T, expressed as a number of individual /48
   prefixes to be allocated from IPv6 prefix P, can be calculated as:

                     ((48-P)*HD)
               T =  2
   Thus, the utilization threshold for an organization requesting
   subsequent allocation of IPv6 address block is specified as a
   function of the prefix size and target HD ratio.  This utilization
   refers to the allocation of /48s to end sites, and not the
   utilization of those /48s within those end sites.  It is an address
   allocation utilization ratio and not an address assignment
   utilization ratio.

   In accordance with the recommendations of [RFC 3194], this document
   adopts an HD-Ratio of 0.8 as the utilization threshold for IPv6
   address space allocations.

   The following table provides equivalent absolute and percentage
   address utilization figures for IPv6 prefixes, corresponding to an
   HD-Ratio of 0.8

        P    48-P          Total /48s        Threshold      Util%

       48       0                   1                1     100.0%
       47       1                   2                2      87.1%
       46       2                   4                3      75.8%
       45       3                   8                5      66.0%
       44       4                  16                9      57.4%
       43       5                  32               16      50.0%
       42       6                  64               28      43.5%
       41       7                 128               49      37.9%
       40       8                 256               84      33.0%
       39       9                 512              147      28.7%
       38      10                1024              256      25.0%
       37      11                2048              446      21.8%
       36      12                4096              776      18.9%
       35      13                8192             1351      16.5%
       34      14               16384             2353      14.4%
       33      15               32768             4096      12.5%
       32      16               65536             7132      10.9%
       31      17              131072            12417       9.5%
       30      18              262144            21619       8.2%
       29      19              524288            37641       7.2%
       28      20             1048576            65536       6.3%
       27      21             2097152           114105       5.4%
       26      22             4194304           198668       4.7%
       25      23             8388608           345901       4.1%
       24      24            16777216           602249       3.6%
       23      25            33554432          1048576       3.1%
       22      26            67108864          1825677       2.7%
       21      27           134217728          3178688       2.4%
       20      28           268435456          5534417       2.1%
       19      29           536870912          9635980       1.8%
       18      30          1073741824         16777216       1.6%
       17      31          2147483648         29210830       1.4%
       16      32          4294967296         50859008       1.2%
       15      33          8589934592         88550677       1.0%
       14      34         17179869184        154175683       0.9%
       13      35         34359738368        268435456       0.8%
       12      36         68719476736        467373275       0.7%
       11      37        137438953472        813744135       0.6%
       10      38        274877906944       1416810831       0.5%
       9       39        549755813888       2466810934       0.4%
       8       40       1099511627776       4294967296       0.4%
       7       41       2199023255552       7477972398       0.3%
       6       42       4398046511104      13019906166       0.3%
       5       43       8796093022208      22668973294       0.3%
       4       44      17592186044416      39468974941       0.2%


8.  Appendix B: Background information


8.1.  Background

   The impetus for revising the 1999 Provisional IPv6 policy started
   with the APNIC meeting held in Taiwan in August 2001.  Follow-on
   discussions were held at the October, 2001 RIPE and ARIN meetings.
   During these meetings, the participants recognized an urgent need for
   more detailed, complete policies.  One result of the meetings was the
   establishment of a single mailing list to discuss a revised policy
   together with a desire to develop a general policy that all RIRs
   could use.  This document does not provide details of individual
   discussions that lead to policies described in this document;
   detailed information can be found in the individual meeting minutes
   at the www.apnic.net, www.arin.net, and www.ripe.net web sites.


8.2.  Why a joint policy

   IPv6 addresses are a public resource that must be managed with
   consideration to the long-term interests of the internet community.
   Although regional registries adopt allocation policies according to
   their own internal processes, address policies should largely be
   uniform across registries.  Having significantly varying policies in
   different regions is undesirable because it can lead to situations
   where "registry shopping" can occur as requesting organizations
   request addresses from the registry that has the most favorable
   policy for their particular desires.  This can lead to the policies
   in one region undermining the efforts of registries in other regions
   with regards to prudent stewardship of the address space.  In cases
   where regional variations from the policy are deemed necessary, the
   preferred approach is to raise the issue in the other regional
   registries in order to develop a consensus approach that all
   registries can support.


8.3.  The size of IPv6's address space

   Compared to IPv4, IPv6 has a seemingly endless amount of address
   space.  While superficially true, short-sighted and wasteful
   allocation policies could also result in the adoption of practices
   that lead to premature exhaustion of the address space.

   It should be noted that the 128-bit address space is divided into
   three logical parts, with the usage of each component managed
   differently.  The rightmost 64 bits, the Interface Identifier
   [RFC2373], will often be a globally-unique IEEE identifier (e.g., mac
   address).  Although an "inefficient" way to use the Interface
   Identifier field from the perspective of maximizing the number of
   addressable nodes, the numbering scheme was explicitly chosen to
   simplify Stateless Address Autoconfiguration [RFC2462].

   The middle 16 bits of an address indicate the subnet ID.  Per [RFC
   3177, RIRs-on-48s], this field will often be inefficiently utilized,
   but the operational benefits of a consistent width subnet field were
   deemed to be outweigh the drawbacks.

   The decisions to inefficiently utilize the bits to the right of /48
   were made under the knowledge and assumption that the bits to the
   left of /48 would be managed prudently and that if done so, will be
   adequate for the expected lifetime of IPv6 [RFC3177].


8.4.  Acknowledgment

   The initial version of this document was produced by The JPNIC IPv6
   policy drafting team consisting of Akihiro Inomata, Akinori Maemura,
   Kosuke Ito, Kuniaki Kondo, Takashi Arano, Tomohiro Fujisaki, and
   Toshiyuki Yamasaki.  Special thanks goes out to this team, who worked
   over a holiday in order to produce an initial document quickly.

   An editing team was then organized by representatives from each of
   the three RIRs (Takashi Arano, Chair of APNIC's Policy SIG, Thomas
   Narten, Chair of ARIN's IPv6 WG, and David Kessens, Chair of RIPE
   NCC's IPv6 WG).

   The editing team would like to acknowledge the contributions to this
   document of Takashi Arano, John Crain, Steve Deering, Gert Doering,
   Kosuke Ito, Richard Jimmerson, David Kessens, Mirjam Kuehne, Anne
   Lord, Jun Murai, Paul Mylotte, Thomas Narten, Ray Plzak, Dave Pratt,
   Stuart Prevost, Barbara Roseman, Gerard Ross, Paul Wilson, Cathy
   Wittbrodt and Wilfried Woeber.

   The final editing of this document was done by Thomas Narten.

## END ##






More information about the ARIN-PPML mailing list