[ppml] Policy Proposal 2005-8: Proposal to amend ARIN IPv6 assignment and utilisation requirement - revised text
gih at apnic.net
Mon Mar 13 16:36:59 EST 2006
The HD ratio is calculated as the ratio of the log of the number of
allocated 'objects' divided by the log of the maximum number of allocatable
If you have been assigned a /32 then the number of allocatable units of /56
is 24 bits, or 16,777216 allocatable objects
If you assigned a single /48 then you have assigned 8 bits, or 256
Your HD ratio for the assignment efficiency an address block with a single
/48 assignment is log(256) / log(16777216) = 0.33333
The proposed HD metric to consider a block fully utilised is 0.94.
This implies that a /32 would be considered fully utilised if you had
allocated 24,154 /48s to end sites, or if you allocated 6,183,424 /56s to
end sites, or 1,582,956,544 /64s to end sites
A more detailed example may see you allocating 2,000 /48s, 2,000,000 /56s
and 10,000,000 /64s - in /56 units this corresponds to 512,000, 2,000,000
and 39,062.5 /56 units respectively. Their total is 2,551,062.5, and the
corresponding HD ratio for a /32 address block with this allocation spread
At 06:15 AM 14/03/2006, Scott Leibrand wrote:
>I think I support this proposal, but I have a couple questions about the
>change to "the use of a /56 as the unit quantity in the calculation of the
>ISP or LIR's end site allocation efficiency." Specifically, will
>assignment of a /48 to a customer automatically count as 256 fully
>utilized /56's for these purposes? What about the allocation of 128
>/64's? Would that count as a fully utilized or fully unutilized /56? Or
>can it be counted as what it is, a half-utilized /56?
>I guess I'm just trying to tease out the implications on an ISPs ability
>to get more space from using different assignment sizes for different
>On 03/13/06 at 1:54pm -0500, Member Services <memsvcs at arin.net> wrote:
> > Policy Proposal 2005-8: Proposal to amend ARIN IPv6 assignment and
> > utilisation requirement has been revised by the authors. This proposal
> > is open for discussion on this mailing list and will be on the agenda at
> > the upcoming ARIN Public Policy Meeting.
> > The current policy proposal text is provided below and is also available
> > at: http://www.arin.net/policy/proposals/2005_8.html
> > Regards,
> > Member Services
> > American Registry for Internet Numbers (ARIN)
> > ### * ###
> > Policy Proposal 2005-8: Proposal to amend ARIN IPv6 assignment and
> > utilisation requirement
> > Authors: Lea Roberts and Thomas Narten
> > Proposal Version: 2 (10-Mar-2006)
> > Proposal type: modify
> > Policy term: permanent
> > Policy statement:
> > This proposal would amend the IPv6 address allocation policies (ARIN's
> > NRPM, section 6) regarding the definition of the default size of End
> > Site assignments and the threshold value for End Site allocation
> > efficiency, no longer assuming the fixed values for End Site assignments
> > established by RFC3177. Many references to "/48" will need to be
> > replaced by "End Site assignment".
> > for example, section 220.127.116.11 should be replaced as follows:
> > 18.104.22.168. Assignment address space size
> > End Users are assigned an End Site assignment from their LIR or
> > ISP. The exact size of the assignment is a local decision for the
> > LIR or ISP to make, using a minimum value of a /64 (when only one
> > subnet is anticipated for the End Site) up to the normal maximum
> > of /48, except in cases of extra large end sites where a larger
> > assignment can be justified.
> > The following guidelines may be useful (but they are only guidelines):
> > - /64 when it is known that one and only one subnet is needed
> > - /56 for small sites, those expected to need only a few subnets
> > over the next 5 years.
> > - /48 for larger sites
> > For end sites to whom reverse DNS will be delegated, the LIR/ISP
> > should consider making an assignment on a nibble (4-bit) boundary
> > to simplify reverse lookup delegation.
> > 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 6.4.4 and for the
> > purposes of measuring utilization as defined in this document.
> > also, section 6.9 will need to be replaced:
> > 6.9. IPv6 Reassignments policy
> > The size of IPv6 address assignments to End Sites is to be
> > determined by the ISP/LIR.
> > ISPs and LIRs may choose whether to make changes to their
> > procedures for assigning address blocks to End Sites. The threshold
> > End Site allocation efficiency level is between 20% to 50% for most
> > ISPs and LIRs when based on a 0.94 HD Ratio. ISPs and LIRs will
> > need to operate address plans according to this target level of End
> > Site allocation efficiency.
> > there's a need to change ARIN NRPM IPv6 Utilization:
> > The ARIN NRPM Section 6.7 will be amended so its IPv6 allocation
> > utilization criteria will reflect the use of a /56 as the unit
> > quantity in the calculation of the ISP or LIR's end site allocation
> > efficiency.
> > 8. Rationale:
> > The current IPv6 Address Allocation and Assignment Policy (section 6 of
> > ARIN's NRPM) indicates that end sites should be allocated a /48 as a
> > uniform allocation unit if using more than one host or one subnet.
> > This proposal alters the existing policy regarding LIR and ISP
> > assignments to End Sites to allow the unit of assignment to be an LIR or
> > ISP decision.
> > In assessing the address utilization efficiency for ISPs or LIRs, the
> > definition of an End Site for the purposes of the calculation of ISP or
> > LIR End Site allocation efficiency, is to be made according to a /56 size.
> > This measure, if undertaken generally by all RIRs, in conjunction with
> > the further measures undertaken by the addressing community regarding
> > increasing the HD ratio to 0.94, would increase the anticipated useful
> > lifetime of IPv6 to encompass a period in excess of 100 years, in which
> > case no further allocation policy changes would be anticipated.
> > A more detailed rationale is available in Geoff Huston's presentation on
> > the subject, at RIPE 50, which can be found at:
> > ------------------------------------------------------------------------
> > Appendix A. References
> > This material is not formally part of the Policy Proposal. It is
> > included here for informational purposes.
> > 1. The IPv6 Address Plan - Geoff Huston
> > http://www.potaroo.net/ispcol/2005-07/ipv6size.html
> > 2. Internet Draft: Issues Related to the Management of IPv6 Address
> > Space - Thomas Narten
> > [unfortunately, the ID expired, so use the URL:
> > 3. Internet Draft: IPv6 Address Allocation to End Sites - Thomas Narten,
> > Geoff Huston & Lea Roberts
> > Timetable for implementation: upon adoption
> > _______________________________________________
> > PPML mailing list
> > PPML at arin.net
> > http://lists.arin.net/mailman/listinfo/ppml
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