[arin-ppml] 2010-8: Rework of IPv6 assignment criteria
farmer at umn.edu
Fri Aug 20 17:25:14 EDT 2010
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
6.5.8. Direct assignments from ARIN to end-user organizations
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
• 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
• 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.
184.108.40.206. 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
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.
220.127.116.11 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
For organizations with larger assignments, a subsequent assignment is
justified when the 0.94 HD-Ratio of the number of /48 equivalents is
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.
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
• 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.
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