On Jun 5, 2013, at 09:11 , Ted Lemon <[email protected]> wrote:

> On Jun 5, 2013, at 12:04 PM, Sander Steffann <[email protected]> wrote:
>> Keep in mind that RIRs won't give you extra address space though. If you 
>> assign /56s to your users then that is what the RIR need-base calculations 
>> are based on (according to current policy).
> 
> So if the ISP says "we need a /48 per customer," the RIR is going to ask 
> "okay, but what are the details of how you will use that /48?"   I don't 
> think so.   Why are we still talking about this?
> 

From ARIN policy:

6.5.2. Initial allocation to LIRs

6.5.2.1. Size
All allocations shall be made on nibble boundaries.
In no case shall an LIR receive smaller than a /32 unless they specifically 
request a /36. In no case shall an ISP receive more than a /16 initial 
allocation.
The maximum allowable allocation shall be the smallest nibble-boundary aligned 
block that can provide an equally sized nibble-boundary aligned block to each 
of the requesters serving sites large enough to satisfy the needs of the 
requesters largest single serving site using no more than 75% of the available 
addresses. 

This calculation can be summarized as /N where N = P-(X+Y) and P is the 
organization's Provider Allocation Unit X is a multiple of 4 greater than 
4/3*serving sites and Y is a multiple of 4 greater than 4/3*end sites served by 
largest serving site.
For purposes of the calculation in (c), an end site which can justify more than 
a /48 under the end-user assignment criteria in 6.5.8 shall count as the 
appropriate number of /48s that would be assigned under that policy.
For purposes of the calculation in (c), an LIR which has subordinate LIRs shall 
make such allocations according to the same policies and criteria as ARIN. In 
such a case, the prefixes necessary for such an allocation should be treated as 
fully utilized in determining the block sizing for the parent LIR. LIRs which 
do not receive resources directly from ARIN will not be able to make such 
allocations to subordinate LIRs and subordinate LIRs which need more than a /32 
shall apply directly to ARIN.
An LIR is not required to design or deploy their network according to this 
structure. It is strictly a mechanism to determine the largest IP address block 
to which the LIR is entitled.

Note that this entire calculation is based on "Provider Assignment Units". 
These are defined as:

2.15. Provider Assignment Unit (IPv6)

When applied to IPv6 policies, the term "provider assignment unit" shall mean 
the prefix of the smallest block a given ISP assigns to end sites (recommended 
/48).


So, if you are giving out multiple /56s to your customers with different 
semantics and not a /48 to each customer, then, your PAU would be /56 and not 
/48.

Also note that if you give residential customers /56s, you will need to be able 
to justify /48s for businesses in terms of the number of /56s they need at each 
end site in order to qualify for an additional allocation. At least this is how 
ARIN policy is currently structured.

YMMV in other RIRs.

Owen

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