[arin-ppml] Why should we do Proposal 121

Owen DeLong owen at delong.com
Thu Dec 9 11:21:50 EST 2010

On Dec 9, 2010, at 6:15 AM, William Herrin wrote:

> On Wed, Dec 8, 2010 at 8:04 PM, Owen DeLong <owen at delong.com> wrote:
>> 1.      Current IPv6 policy is being interpreted to the detriment of ISPs that
>>        have subordinate ISPs. Subordinate ISPs should be able to get PA
>>        space from their upstreams equivalent to what they would be able
>>        to get directly from ARIN. Currently, ARIN is not allowing for the
>>        possibility that an ISP would reallocate /32s (or larger) to their
>>        subordinate ISPs.
> Hi Owen,
> Can you suggest a scenario in which a a subordinate /32 allocation is
> unambiguously appropriate on the technical merits versus the same ARIN
> allocation directly to the subordinate ISP? It seems to me like you
> might have to make some unwarranted assumptions to get there.
I'm not sure I understand the question. It is my opinion that the policy for
space that an ISP can reallocate to a subordinate ISP should be identical
to the policy governing what space ARIN can allocate to that same ISP.
Either the policy is good stewardship of the address space or it is not. If
it is not good policy, then, we should change the ARIN policy. If it is good
policy, then the ISP should be able to make the reallocation if that is
where the other ISP prefers to get their space.
>> 2.      HD Ratio is confusing to people and of dubious value vs. basing
>>        utilization on simple ratios.
> Agree 100%. In addition to being cryptic, ARIN's HD ratio is a
> misapplication of the relevant research. The math has been modified in
> a way inconsistent with what little empirical data supports the
> original observations. It should go away.
>> 3.      A large number of historic outages have been the direct result
>>        of people being generally bad at bitmath. By moving allocations
>>        to nibble boundaries, we can reduce the likelihood of these
>>        errors by removing complex bitmath from most network deployments.
> Agree 100%. There are many good reasons for limiting the bit
> boundaries on which allocations are made and the nibble is a natural
> boundary for IPv6.
>> 4.      The current complexity of getting allocations larger than /32 from
>>        ARIN is resulting in many providers choosing, instead, to shrink
>>        the size of assignments they give to end sites to less than /48.
>>        If this practice becomes wide spread, it will likely reduce possible
>>        innovations in the SOHO realm because vendors will generally
>>        implement to the lowest common denominator.
> I don't personally find a reduction from /48 a compelling argument. If
> anything, a more reasonable recommendation than /48 would tend to help
> folks avoid foolish mistakes like /64... which actually could create
> the lowest-common-denominator effect you fear.
Personally, I don't think that /48 is unreasonable. However, I will point
out that proposal 121 does not prevent ISPs from choosing to give
out less than  a /48, it merely sets an upper bound at /48 and makes
it easy for the ISP to get sufficient space to allow for /48s if they choose.

Is there a reason you think /48s are "unreasonable"? Personally, I think
they are quite reasonable.


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