[arin-ppml] Policy Proposal: A Modest Proposal for an Alternate IPv6 Allocation Process

Eliot Lear lear at cisco.com
Fri Jun 5 14:26:15 EDT 2009

This proposal states the following regarding sparse allocation:

> Unproven: with sparse allocation, we can allow organizations to expand
> by just changing their subnet mask so that they don't have to announce
> additional routes into the DFZ. This claim is questionable. With
> sparse allocation, we either consume much larger blocks that what we
> assign (so why not just assign the larger block?) or else we don't
> consume them in which case the org either has to renumber to expand or
> he has to announce a second route. Worse, because routes of various
> sizes are all scattered inside the same address pool, its impractical
> to detect or filter out the traffic engineering routes.

To start with, the reason users want sparse allocation is so that they 
do not have to undertake a (presumably) large renumbering exercise.  Any 
policy that requires additional renumber will encourage use of ULAs tied 
to NAT.  It is already difficult to argue against those who want to 
insulate themselves from renumbering events with ULAs.  This policy 
would be the nail in the coffin for those of us who like globally unique 
and routed addresses.

And so the question: should ARIN be encouraging use of ULAs *instead* of 
globally routable address space?


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