[arin-ppml] Draft Policy ARIN-2019-10: Inter-RIR M&A - Seeking Community Comments

hostmaster at uneedus.com hostmaster at uneedus.com
Mon Jul 15 23:17:48 EDT 2019

I will take a stab at what this means.

I am choosing the block containing my IPv6 addresses as an example. If you 
go to the ARIN whois site and look up network NET6-2600, you will see that 
this network range is 2600::  to 260f:ffff:ffff:ffff:ffff:ffff:ffff:ffff. 
This network is otherwise stated as 2600::/12., and shows that it is 
assigned to ARIN by IANA.  IANA always assigns blocks of IPv6 addresses to 
RIR's in /12 blocks.

A link to this is https://whois.arin.net/rest/net/NET6-2600-1

This means the ENTIRE BLOCK has been assigned to ARIN, and therefore ARIN 
controls the reverse DNS of this entire block.

ARIN allocates portions of this block to LIR's or ISP's and provides a 
pointer to the DNS servers designated by the entities that have been 
allocated the IPv6 blocks contained within the larger /12 block.

If RIR transfers were permitted, ARIN would have to give control of the 
transfered addresses within this block to the RIR(s) involved and would no 
longer control the entire block. PKI also follows from top to bottom and 
may not work properly if portions of the block are assigned to different 

More generically, I would call this "ARIN giving up control of portions of 
the Reverse DNS zones to another RIR."  It breaks the block apart, thus 
the poster's term "fracturing".

I believe that ARIN should maintain control of 100% of each IPv6 block 
that it receives from IANA.  I can understand the term "fracturing" being 
used to describe what would happen to IPv6 blocks received from IANA, if 
ARIN gave up control of specific addresses contained within that block to 
another RIR.  If someone wants to receive IPv6 addresses from another RIR, 
I believe that they need to renumber into a block belonging to that RIR.

Generally ARIN (and other RIR's) use what is called "sparse allocation" 
when allocating IPv6 blocks.  This means that addresses before and after 
each allocation are left vacant, so that a specific allocation can be made 
larger without having to allocate more than one block of addresses, 
controlling the growth of the routing tables.  Instead, the existing block 
is made larger.  For example a /35 might be expanded to a /32, and this 
was done when the policy was changed to allocate ISP's a /32 by default, 
and this way the addresses continue to remain in a single block of a 
larger size.

Albert Erdmann
Network Administrator
Paradise On Line Inc.

On Tue, 16 Jul 2019, Job Snijders wrote:

> Dear Fernando,
> On Mon, Jul 15, 2019 at 08:13:12PM -0300, Fernando Frediani wrote:
>> I will comment only in one of the points, the other I believe are
>> really well explained by others and it doesn't seem good to 'rain on
>> the wet floor'.
> I'm sorry but I don't think we can skip over some of these "objections"
> without further substantiation on what the terminology actually means.
> The term "fracturing the Reverse DNS zone" was coined just a few hours
> ago and I don't think most people have any idea what it means. At least
> I don't! :-)
> I googled the term "fractured DNS", and from what I understand it is a
> term used in context of alternative DNS roots (DNS roots other than
> the ICANN/IANA root most of us use). I fail to see what "fractured DNS"
> might mean in our current context of inter-RIR IPv6 transfers.
> Kind regards,
> Job
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