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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:
---------------------------
ARIN:
- Adopted, awaiting implementation by staff.
RIPE:
- 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
customers.
Utilized:
(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. Allow all requesters to round their requests up to the next nibble boundary. 4. Allow LIRs to request 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 proposal. 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 ------------------------------------------------ Advantages: - 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. Disadvantages: - 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' http://www.apnic.net/policy/ipv6-address-policy#5.5
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