[ppml] Proposed Policy: IPv4 Micro-allocations for anycast services (experimental)

Member Services memsvcs at arin.net
Fri Feb 10 10:31:43 EST 2006

ARIN received the following proposed policy. In accordance with the ARIN
Internet Resource Policy Evaluation Process, the proposal is being
posted to the ARIN Public Policy Mailing List and being placed on ARIN's

The ARIN Advisory Council (AC) will review the proposal and within ten
working days may decide to:
1)  Support the proposal as is,
2)  Work with the author to clarify, divide or combine one or more
policy proposals, or
3)  Not support the policy proposal.

If the AC supports the proposal or reaches an agreement to work with the
author, then the proposal will be posted as a formal policy proposal to
the Public Policy Mailing List and it will be presented at the Public
Policy Meeting. If the AC does not support the proposal, then the author
may elect to use the petition process to advance the proposal. If the
author elects not to petition or the petition fails, then the proposed
policy will be considered closed.

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Policy Proposal Name: IPv4 Micro-allocations for anycast services

Author: David Williamson

Proposal type: new

Policy term: temporary

Policy statement:

In the NRPM IPv4 section, renumber 4.4 to 4.4.1, and add:

4.4.2 Micro-allocations for anycast services - ARIN will make
micro-allocations to organizations wishing to deploy anycast based
services, provided they meet the following criteria:

     * All of the criteria normally required to receive IPv4 space, AND
     * The organization must have multiple (at least two) discrete
       multi-homed networks.
     * The organization must advertise directly allocated networks from
       each multi-homed site.

Micro-allocations for anycast services will be no longer than a /24.
These allocations will be made out of blocks reserved for
micro-allocation purposes.  ISPs and other organizations receiving these
micro-allocations will be charged under the ISP fee schedule, while
end-users will be charged under the fee schedule for end-users.

This policy is experimental, and is limited to 16 allocations and two
years from adoption.  In addition, organizations may receive no more
than one microallocation under this policy.


There are an increasing number of anycast-based applications being
offered by service providers and other organizations.  Indeed, many
basic infrastructure services (like the DNS root servers) are already
anycast based.  (See RFC 1546 for an authoritative discussion of anycast

It's worth noting that IPv6 has anycast built into the protocol itself.
  This is a sign that there is significant community interest in anycast
as a technology, and highlights the lack of IPv4 allocation policy for

Deployment of new services is severely hampered by current IPv4
allocation policies.  For organizations that do not have legacy IP
space, justifying a /22 to serve a handful of addresses is effectively
impossible.  As many ISPs also filter routes longer than /22, it is
impractical to use a longer mask for any netblock that is utilized for
an anycast service.  This situation is also generally unfavorable to
younger organizations, while giving older organizations that do have a
surplus of legacy space a competitive advantage.

In light of this, some organizations may simply lie about their
addressing needs in order to convince an RIR or LIR that a /22 is
required, when a much smaller network would suffice.  This is not a
behavior that should be encouraged by policy.

The obvious answer is that a micro-allocation scheme needs to be created
to allow organizations deploying anycast services to acquire a network
of more appropriate size.

It is also clear that a micro-allocation policy that makes it easier for
organizations to acquire small netblocks may lead to additional improper
allocations to organizations that simply wish to acquire additional
small blocks of space.  This policy proposal attempts to address that by
requiring more stringent requirements for such allocations.

A previous policy proposal (2005-6) is similar to this proposal, but
with a few significant changes.  There was signficant negative feedback
to that policy based on a couple of key difficulties, which this
proposal attempts to address.

The primary difficulty is that an anycast network looks much like a
normal multihomed network from the outside.  This led to the consensus
belief that the earlier policy proposal would be abused by organizations
that wouldn't otherwise qualify for address space.  This proposal futher
restricts allocations such that only organizations that are already
demonstratably multihomed with direct allocations can possibly qualify.
  Such organizations will typically have little use for a small
allocation unless they really intend to use it for a specific purpose.

In addition, this policy is marked as experimental and has a sunset
clause, which will definitively prevent widespread abuse.  It is hoped
that operational experience will show that this policy is not seeing
abuse, and it can later be modified to be permanent.  In the event that
this policy is widely abused, the total damage is limited and will be
fixed in a relatively short time span.

Timetable for implementation: immediate

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