[arin-ppml] A modest proposal for IPv6 address allocations

[Garry Dolley]

On Sun, May 31, 2009 at 02:42:14PM -0400, Kevin Loch wrote:
> James Hess wrote:
>> Why allocate  /32s  from a pool reserved for  /32s?
>> It would perhaps make more sense, as a matter of policy, that a
>> special allocation strategy be utilized,  that the  /48s,  /32s, and
>> /24s  are allocated from just one pool.
>> And that they be allocated in a manner  that maximizes the duration
>> during which the 2nd/3rd allocation request would be contiguous with
>> the earlier allocation.
>
> This is called "sparse allocation" method and is what APNIC uses today.  It 
> was one of the the justifications for giving each RIR blocks of /12
> instead of /23.  I would like to know why ARIN is not using this method.

I thought ARIN *was* using this method.  Or at least keeping
surrounding upper blocks free when allocating /32's.  I believe this
is the "leftmost" method per RFC 3531 [1], but I could be wrong on
that, RFC 3531 goes over my head a lot.

I did WHOIS lookups on some /32's surrounding my own and found the
following:

2607:f2e0::/32 - allocated
2607:f2e1::/32
2607:f2e2::/32
2607:f2e3::/32
2607:f2e4::/32
2607:f2e5::/32
2607:f2e6::/32
2607:f2e7::/32

2607:f2e8::/32 - allocated
2607:f2e9::/32
2607:f2ea::/32
2607:f2eb::/32
2607:f2ec::/32
2607:f2ed::/32
2607:f2ee::/32
2607:f2ef::/32

2607:f2f0::/32 - allocated
2607:f2f1::/32
2607:f2f2::/32
2607:f2f3::/32
2607:f2f4::/32
2607:f2f5::/32
2607:f2f6::/32
2607:f2f7::/32

2607:f2f8::/32 - allocated
2607:f2f9::/32
2607:f2fa::/32
2607:f2fb::/32
2607:f2fc::/32
2607:f2fd::/32
2607:f2fe::/32
2607:f2ff::/32

2607:f300::/32 - allocated
2607:f301::/32
2607:f302::/32
2607:f303::/32
2607:f304::/32
2607:f305::/32
2607:f306::/32
2607:f307::/32

2607:f307::/32 - allocated
2607:f308::/32
2607:f309::/32
2607:f30a::/32
2607:f30b::/32
2607:f30c::/32
2607:f30d::/32
2607:f30e::/32
2607:f30f::/32


The /32's not marked "allocated" don't have a WHOIS entry, so I
assume they are available.

Therefore, each /32 can potentially grow into a /29 (I *think* my
math is right on that, 3 more bits gives 7 additional /32's beyond
the initial allocation, for a total of 8 /32's).

Is this what is meant by "sparse allocation"?

Additionally,

This gives room for each /32 holder to grow by simply a subnet mask
change, thereby allowing (although not requiring) their route
announcement(s) to not necessarily grow linearly with the addition
of IP space.  I know this isn't news to anyone, but seeing how
allocation practices can have such an immediate effect on the number
of route announcements, I don't see how discussions about allocation
policies can be completely separated from routing.

As Joe Mainmon recently put it, "please put a nail into the mantra
of registries not being involved in routing."


1. RFC 3531, "A Flexible Method for Managing the Assignment of Bits
   of an IPv6 Address Block"
   http://tools.ietf.org/html/rfc3531

-- 
Garry Dolley
ARP Networks, Inc. | http://www.arpnetworks.com | (818) 206-0181
Data center, VPS, and IP Transit solutions
Member Los Angeles County REACT, Unit 336 | WQGK336
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