[sig-policy] Prop-098 Revision 2 (redlined version showing changes from

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  • Subject: [sig-policy] Prop-098 Revision 2 (redlined version showing changes from version 1)
  • From: Owen DeLong <owen at delong dot com>
  • Date: Wed, 1 Feb 2012 14:20:56 -0800
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      prop-098-v002: Optimizing IPv6 allocation strategies (simplified)
      Author:        Owen DeLong
                      <owen at delong dot com>
      Version:       2
      Date:          1 February 2012
      1. Introduction
      This is a proposal to allow for more generous IPv6 allocations to
      service providers in order to promote better aggregation and easier
      optimization across their networks as they grow.
      2. Summary of current problem
      2.1. Many LIRs are of the errant belief that they must fit their entire
            subscriber base within a single /32 and that they cannot easily
            obtain larger allocations from their RIR or NIR.
      2.2. Many network outages have been caused by on-the-fly bit math errors
            and by aligning addressing blocks on nibble boundaries, at least
            where it makes sense, these errors can be reduced or eliminated.
      2.3. Continued proliferation of the /32 mindset described in (1) above
            will eventually lead to significant unnecessary disaggregation and
            larger IPv6 routing tables.
      2.4. The HD ratio, while a good mathematical model leaves much to be
            desired as an address administration tool. Using nibble-boundaries
            and rounding up actually yields similar results with simpler math.
      3. Situation in other RIRs:
            - Adopted, awaiting implementation by staff.
            - As RIPE NCC seems to be currently issuing generous allocations,
              the author does not currently intend to submit a proposal to
              RIPE. However, the author may subsequently submit a policy to
              align RIPE allocations on nibble boundaries.
      LACNIC and AfriNIC:
            - Author is working on proposals for these regions.
      4.  Details of the proposal
      Amend IPv6 allocation policy as follows:
      1. Add the following definitions:
            Nibble boundary: The point in a binary string where one hex digit
            ends and another begins.
            Provider Allocation Unit: The unit by which an LIRs utilization is
            measured. It is defined as the smallest reassignment unit used by
            the provider.
      2. Redefine the following terms:
            End site:
            A single structure or service delivery address, or a
            single tenant within a multi-tenant structure.
            - The intent of this definition is to provide greater clarity and
              flexibility in allowing ISPs to meet the needs of their
            (i)  A provider allocation unit shall be considered fully
                 utilized when it is assigned to an end site or allocated to a
                 customer LIR.
            (ii) The utilization percentage of a block at the LIR level is
                 calculated as the fraction of total provider assignment units
                 which have been assigned to end sites or allocated to
                 customer LIRs.
      3. Make all allocations and assignments on nibble boundaries.
      3. Allow all requesters to round their requests up to the next nibble boundary.

      4. Allow LIRs to request nibble-aligned blocks of any size greater than
          or equal to /36.
          4.1 The default minimum is /32 unless the provider specifically
              asks for a /36.
          4.2 The maximum allocation shall be the smallest nibble aligned block which allows
              the provider to accommodate 5 years of projected customer
              utilization based on assigning each customer end-site one
              provider allocation unit without exceeding a 75% utilization. If
              the provider has no allocation or assignment history, the
              provider may specify their provider allocation unit at the time
              of application.
          4.3 An LIR which has subordinate LIRs may count the required
              allocation for each subordinate LIR as fully utilized blocks of
              PAUs in the calculation for 4.2.
      5. Modify the subsequent allocation process.
           5.1 To qualify for a subsequent allocation, an LIR must meet one of
               the following two criteria:
               - 75% or more utilization of their total address space, OR
               - One or more facilities which have reached a 90% utilization of
                 the blocks allocated to those facilities and there are no
                 available blocks of sufficient size in the providers current
                 allocation(s) to expand those facilities and/or add new facilities.
           5.2 When making a subsequent allocation, APNIC will use the
               following procedure:
               Whenever possible, expand one or more existing allocations to
               the next nibble as needed.
               When the above expansion cannot meet the need, make a new
               allocation large enough to encompass all existing allocations
               plus the need justified in this request.
               Such allocation shall not exceed a /16, but, a provider may
               receive as many /16s as are required to meet their justified
               When this occurs, an LIR is encouraged to vacate their old
               allocations through attrition and return vacated space when
               feasible. The LIR is not required to vacate the space, but, it
               is encouraged. Once vacated, the space should be returned.
      	Nothing in this section shall preclude a requestor's right to expand on nibble-boundary alignments if that is desired.
      6. Allow LIRs with existing allocations to expand their allocation size
          if they are eligible for a larger block under the criteria in this
          Any LIR which received an allocation under previous policies which is
          smaller than what they are entitled to under this policy may receive
          a new initial allocation under this policy based on the procedure and
          criteria in 5.2.
      5.  Advantages and disadvantages of the proposal
            - Provides nibble-boundaries for direct allocations and for at
              least one level of network hierarchy within the LIR, reducing the
              potential for human factors errors.
            - Increases the potential for network aggregation by issuing very
              large blocks to ISPs.
            - Reduces the potential for harmful under-sized assignments to end
              users by removing any incentive to do so.
            - Simplifies the IPv6 allocation policy by removing logarithmic
              computations in favor of simple ratios.
            - Reduces the number of times any given LIR will need to return to
              APNIC for additional allocations.
            - Allows for better network planning and growth.
            - May increase IPv6 address allocation. Probable impact over 50
              years would reduce IPv6 free pool from 99.9995% to 99.62%.
      6.  Effect on APNIC Members
      APNIC LIR members will be able to obtain significantly larger blocks of
      IPv6 addresses and both receive and make their initial allocations and
      assignments on nibble boundaries to simplify human factors and network
      management while improving aggregation.
      7. Effect on NIRs
      This policy should not significantly impact NIRs.
      8. References
      [1] Section 5.5, 'Assignment', in 'APNIC IPv6 Allocation Policy'