[ppml] Solicing comments: IPv4 to IPv6 Migration Incentive Address Space

Scott Beuker scott.beuker at sjrb.ca
Thu Jun 28 20:27:58 EDT 2007


The most fundamental problem I have with your proposal is the
inefficiencies of automatic IPv6 assignments via translation from IPv4.
One of the benefits we should hope to achieve from a transition to IPv6
is to reduce the fragmentation of assignments in the IPv4 space. So the
status quo of having organizations apply for and receive a single IPv6
assignment from ARIN is highly desirable. As has been stated, approval
for IPv6 address space shouldn't be a stumbling block for anyone who has
IPv4 space.

In light of this, the rest of the proposal is moot, because it seems the
crux is the automatic mapping of address space. But I do applaud anyone
making an effort to move IPv6 adoption forward, and hope you will
continue your work. I just think you may need to go back to the drawing
board on this one.


Scott Beuker
Network Architect, IP Backbone
Shaw Internet Engineering

-----Original Message-----
From: ppml-bounces at arin.net [mailto:ppml-bounces at arin.net] On Behalf Of
William Herrin
Sent: Thursday, June 28, 2007 9:32 AM
To: John Paul Morrison
Cc: ppml at arin.net
Subject: Re: [ppml] Solicing comments: IPv4 to IPv6 Migration Incentive
Address Space

On 6/27/07, John Paul Morrison <jmorrison at bogomips.com> wrote:
> I do not support this proposal as it essentially duplicates the IPv6 
> address space already allocated to IPv4 users, documented in RFC 3056 
> (6to4).


  First, thank you for privately discussing 6to4's functionality with
me. You were very helpful and informative.

  You are not alone in suggesting that 6to4 might suitably replace the
Migration Incentive Space proposal, however 6to4 has several issues
which would need to be addressed before it could be considered a valid
alternative. I'd like to find if there is a consensus on ppml as to
whether those issues should be addressed in 6to4. If they should, I'll
start working on such a proposal with the intent that it replace the
Migration Incentive Space proposal. If they should not, then I would ask
that 6to4 be considered irrelevant to and dropped from the discussion.

6to4 Problem #1: Implementation of 6to4 is an optional component of the
IPv6 protocol. Devices confronted with a 2002:: address may but need not
recognize that packets to such a destination should be encapsulated in
an IPv4 packet. The Migration Incentive Space proposal is intended to
rely on only those components of IPv6 which are mandatory.

6to4 Problem #2: Its unclear whether the authors of RFC 3056 intended
that it be possilble for prefixes within 2002:: to be announced into the
global IPv6 BGP table so that all native IPv6 networks could reach such
hosts without IPv4 encapsulation. Indeed, some parts of the document
suggest that an available IPv6 route should NOT take priority over
encapsulation. For 6to4 to reasonably replace the Migration Incentive
Space, it would need to be clarified that ARIN encourages IPv4 holders
to announce an appropriately selected 2002:: route, that remote IPv6
systems should give native IPv6 routes to 2002:: destinations priorirty
over the encalsulated IPv4 route, and that ARIN intends such blocks
within 2002:: to have the same validity as any other IPv6 block they
assign or allocate.

6to4 Problem #3: Its unclear whether the authors of RFC 3056 intended
that prefixes within 2002:: continue to exist in IPv4's post-exhaustion
phase when IPv6 has become the dominant protocol. The Migration
Incentive Space is intended to be a permanant solution whose addresses
continue to see use after IPv4's end of life.

6to4 Problem #4: ARIN does not control the reverse DNS for 6to4 prefixes
associated with the IPv4 blocks which ARIN manages. It is presently
managed by the NRO, an organization in which ARIN participates (see
https://6to4.nro.net/). The documentation for 6to4 reverse dns states
that, "This password is not mandatory when the site is accessed from
inside your 6to4 source address. It is intended to prevent an arbitrary
access from locking out the domain if the address is not static. (It is
recognized that this places far less trust than normal in the
correctness of a 6to4 delegation)." For 6to4 to work as a replacement
for the Migration Incentive Space, reverse DNS for the blocks under
ARIN's authority would need to be operated with a degree of security and
access comperable to what ARIN applies to its normal delegation of
reverse DNS.

So, the question I put to you and to the others who have suggested 6to4
is this: Do we seek changes and clarifications to address these four
problems or do we drop 6to4 from consideration as an alternative to the
Migration Incentive Space proposal?

Bill Herrin

William D. Herrin                  herrin at dirtside.com  bill at herrin.us
3005 Crane Dr.                        Web: <http://bill.herrin.us/>
Falls Church, VA 22042-3004
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