[ppml] Policy Proposal: IPv6 Assignment Size Reduction

David Williamson dlw+arin at tellme.com
Mon Oct 22 12:06:54 EDT 2007

On Mon, Oct 22, 2007 at 11:23:21AM -0400, Member Services wrote:
> ARIN received the following policy proposal. In accordance with the ARIN
> Internet Resource Policy Evaluation Process, the proposal is being
> posted to the ARIN Public Policy Mailing List (PPML) and being placed on
> ARIN's website.
> Policy Proposal Name: IPv6 Assignment Size Reduction

I am entirely against this proposal.

As others have noted, this flies in the face of existing IETF standards
and recommendations.  The vast majority of existing LLA implementations
expect the /64 boundary to be enforced, and EUI-48 isn't generally
implemented, while EUI-64 is.  (I'll also note that DHCP6 is still
primitive, to my mild annoyance.)

In addition, the current v6 environment is focused on subnets, not
hosts, which seems to be something that many people are missing.  As
Geoff Huston noted:

>The intent of the use of /56 in the efficiency metric was to provide a 
>common mechanism to measure the efficiency of end-site prefix 
>assignments irrespective of the size of individual end site assignments, 
>and explicitly not to measure the efficiency of address assignments to 
>i.e the presumption in terms of this end site prefix efficiency measure 
>is that the assignments with end-sites are not the subject of the review.

Let me expand on that.  End-sites and their efficiency are essentially
irrelevant to the overall numbering and routing scheme in v6.  Again,
hosts just don't matter, and all that counts for anything is the number
of subnets.

Personally, I think the /64 everywhere decision was pretty dumb, but it
has some advantages.  We need to stop thinking about how many hosts we
can squeeze into a network, and we can stop worrying about picking the
right subnet mask when a new network is turned up. (what if I have to
remask it later? is no longer an interesting question.)

If we collectively get out of v4 mindset, we can do some seriously
creative things in v6.  Let's not reimpose v4 restrictions on the
world, which is exactly what this proposal does.  Yes, we're not being
super efficient with number policy, but that's not what we need at this
point in time.  If, 50 years from now, we're running low on address
space, things will certainly change.  It's presumptuous of us to think
that we know how this is really going to work out over that kind of
time period, though.

Again, for clarity, I really really oppose this policy proposal.


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