[arin-ppml] A modest proposal for IPv6 address allocations
gdolley at arpnetworks.com
Sun May 31 08:45:47 EDT 2009
On Sun, May 31, 2009 at 12:19:38AM -0500, 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.
> e.g. A /48 may be allocated, but the entire /24 could be left
> "internally" reserved for as long as possible.
> So if/when a recipient of a /48 allocation requests their next
> allocation, it would be preferred that the /32 will be a block that
> begins with, and contains the same address space as their /48, in
> addition to the added space.
> And if a third allocation is requested, the /24 also, would be chosen
> so as to overlap with and contain the /32.
> This has the benefit that they don't need a second advertisement, and
> never have a need to return addresses.
> If/when ARIN's allocations of V6 space ever becomes so dense that
> reserving the entire /24 in advance for recipients of /48s is no
> longer feasible, it should be the oldest-assigned /48 that are
> first "blocked" from expanding contiguously to a /24, followed by the
> oldest /32 allocations.
> With preference of the "blocking" assignments preventing contiguous
> expansions to /24 over contiguous expansions to /32.
James makes a good point.
Since the v6 space is so large, ARIN can, for example, allocate an
org a /32, but leave the neighboring /32 unallocated for as long as
possible, so if/when you need another /32, they just change your
subnet mask to a /31. No renumbering required.
I once was lucky to have this happen w/ v4. I had a /20 from ARIN,
then at some point requested another. The neighboring /20 was
available, so they just made it a /19.
Any org in the position to allocate IP space can do this . For
example, if I give a /56 to a customer, I'll pretend as if it were a
/48, so if that customer ever needed more subnets than a /56 has to
offer, I'll just change their subnet mask to a /48. They don't need
to renumber or deal with two discontiguous /56's.
Therefore, having ARIN use separate "pools" for different allocation
sizes would not be a good idea.
1. RFC 3531, "A Flexible Method for Managing the Assignment of Bits of
an IPv6 Address Block"
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
More information about the ARIN-PPML