[arin-ppml] 2010-8: Rework of IPv6 assignment criteria

[David Farmer]

The following is a major rewrite of 2010-8: Rework of IPv6 assignment 
criteria, based on input received at the last ARIN meeting and other 
discussions;  I'm interested in feedback

Thanks

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6.5.8. Direct assignments from ARIN to end-user organizations

6.5.8.1 Criteria

Organizations may justify an initial assignment for addressing devices 
directly attached to their own network infrastructure, with an intent 
for the addresses to begin operational use within 12 months, by meeting 
one of the following criteria:

a. Having a previously justified IPv4 end-user assignment from ARIN or 
one of its predecessor registries, or;

b. Currently being IPv6 Multihomed or immediately becoming IPv6 
Multihomed and using an assigned valid global AS number, or;

c. By having a network consisting of a total of 1000 or more hosts, or;

d. By providing a reasonable technical justification indicating why IPv6 
addresses from an ISP or other LIR are unsuitable.

Examples of justifications for why addresses from an ISP or other LIR 
may be unsuitable include, but are not limited to:

• An organization that operates infrastructure critical to life safety 
or the functioning of society can justify the need for an assignment 
based on the fact that renumbering would have a broader than expected 
impact than simply the number of hosts directly involved. These would 
include: hospitals, fire fighting, police, emergency response, power or 
energy distribution, water or waste treatment, traffic management and 
control, etc…
• Regardless of the number of hosts directly involved, an organization 
can justify the need for an assignment if renumbering would affect 1000 
or more individuals either internal or external to the organization.
• An organization with a network not connected to the Internet can 
justify the need for an assignment by documenting a need for guaranteed 
uniqueness, beyond the statistical uniqueness provided by ULA (see RFC 
4193).
• An organization with a network not connected to the Internet, such as 
a VPN overlay network, can justify the need for an assignment if they 
require authoritative delegation of reverse DNS.

6.5.8.2. Initial assignment size

Organizations that meet at least one of the initial assignment criteria 
above are eligible to receive a minimum assignment of /48. Requests for 
larger initial assignments, reasonably justified with supporting 
documentation, will be evaluated based on the number of sites and the 
number of subnets needed to support a site.

Organizations may request up to a /48 for each site in their network. If 
an organization elects for smaller prefixes for some sites, these will 
be aggregated into an equivalent number of whole /48 prefixes.

In the rare case where more than a /48 is justified for an individual 
site, ARIN will evaluate such requests using the 0.94 HD-Ratio metric of 
the number of /64 subnets to determine a justified number of equivalent 
/48 prefixes. Example: it is necessary to justify 33,689 subnets to 
receive a second /48 for an individual site.

The overall initial assignment size will be rounded up to the next 
nibble boundary using the following table, based on the number of /48 
equivalents justified above:

One and only one /48 equivalent justified, receives a /48 initial 
assignment;
More than 1 but less than or equal to 10 /48 equivalents justified, 
receives a /44 initial assignment;
More than 10 but less than or equal to 100 /48 equivalents justified, 
receives a /40 initial assignment;
More than 100 but less than or equal to 1,500 /48 equivalents justified, 
receives a /36 initial assignment;
More than 1,500 /48 equivalents justified, receives a /32 initial 
assignment or larger.

In cases where more than 1,500 /48 equivalents are justified an initial 
assignment of /32 will be made, unless a larger initial assignment is 
justified using the 0.94 HD-Ratio of the number of /48 equivalents 
rounded up to the next nibble boundary.

Each initial assignment, up to at least /40, will receive a reservation 
for growth of at least the next nibble boundary beyond the initial 
assignment. Such reservations are not guaranteed and ARIN, in its sole 
discretion, may assign them to other organizations at any time. ARIN, in 
its sole discretion, may make larger reservation based on an 
organization’s growth projections.

6.5.8.3 Subsequent assignments

For organizations with a /48 assignment, a subsequent assignment is 
justified when the utilization of 33,689 /64 subnets can be demonstrated 
for a single site, or when additional sties are added to an 
organization’s network.

For organizations with larger assignments, a subsequent assignment is 
justified when the 0.94 HD-Ratio of the number of /48 equivalents is 
exceeded:

For an assignment of /44, a utilization of 14 or more /48 equivalents is 
necessary to justify a subsequent assignment;
For an assignment of /40, a utilization of 184 or more /48 equivalents 
is necessary to justify a subsequent assignment;
For an assignment of /36, a utilization of 2487 or more /48 equivalents 
is necessary to justify a subsequent assignment.

When possible, subsequent assignments will be made from contiguous 
adjacent address blocks. If the current assignment is within an 
available contiguous reservation, then the new assignment will be made 
from within the reservation with the total assignment sized at the next 
nibble boundary. If a contiguous reservation is not available, then a 
separate new assignment sized at the next nibble boundary will be made.

When a new non-contiguous assignment is made, ARIN, in its sole 
discretion, may make a reservation for growth of at least the next 
nibble boundary. Such reservations are not guaranteed and ARIN, in its 
sole discretion, may assign them to other organizations at any time.

Rationale:

This proposal provides a complete rework of the IPv6 end-user assignment 
criteria, removing the dependency on IPv4 policy, and providing clear 
guidance in requesting larger initial assignments.

The following general concepts are included:

• Previously justified IPv4 resources may be used to justify the need 
for IPv6 resources.
• Internet multihoming is sufficient justification for an ipv6 end-user 
assignment in and of itself.
• Other end-users must justify why an ISP or LIR assignment is not 
sufficient for their needs.
• Organizations with multiple sites are allowed to request a /48 for 
each site.
• Providing a sufficiently large initial assignments and reservations 
will reduce route table growth caused by subsequent assignments.
• While HD-Ratio is not eliminated, it is not necessary for most 
end-users to understand the details of the HD-Ratio.