[sig-policy] prop-098 Returned to mailing list
prop-098 Optimizing IPv6 allocation strategies (simplified), did not
reach consensus at the APNIC 32 Policy SIG. Therefore, this proposal is
being returned to the author and the Policy SIG mailing list for further
discussion.
Proposal details
----------------
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.
Proposal details including the full text of the proposal, history, and
links to mailing list discussions are available at:
http://www.apnic.net/policy/proposals/prop-098
Regards
Andy, Skeeve, and Masato
________________________________________________________________________
prop-098-v001: Optimizing IPv6 allocation strategies (simplified)
________________________________________________________________________
Author: Owen DeLong
<owen at delong dot com>
Version: 1
Date: 2 August 2011
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. Make all allocations and assignments on nibble boundaries.
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 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.
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.
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
needs.
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.
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