legacy /8

Paul Vixie vixie at isc.org
Mon Apr 12 02:23:48 CDT 2010

> From: David Conrad <drc at virtualized.org>
> Date: Sun, 11 Apr 2010 13:52:24 -1000
> On Apr 11, 2010, at 10:57 AM, Paul Vixie wrote:
> > ... i'd like to pick the easiest problem and for that reason i'm urging
> > dual-stack ipv4/ipv6 for all networks new or old.
> Is anyone arguing against this?

yes.  plenty of people have accused ipv6 of being a solution in search of
a problem.  on this very mailing list within the last 72 hours i've seen
another person assert that "ipv6 isn't needed."  while i tend to agree
with tony li who of ipv6 famously said it was "too little and too soon" we
have been Overtaken By Events and we now have to deploy it "or else".  the
only way we're going to do that is with widescale dual-stack, either
native dual-stack (which is generally easy since ipv6 address space is
cheap and plentiful) or dual-stack-lite (which is ipv4-NAT ipv6-native
with aggregated encap/decap at the POP or edge) or with any other method
(or trick) that comes to mind or seems attractive.

what we can't do is presume that any form of "ipv4 steady state forever" or
"wait for something better than ipv6 before abandoning ipv4" is practical,
or that these would be less expensive (in both direct cost, indirect cost,
and network/market stability) than "dual-stack now, ipv6-mostly soon, and
ipv6-only eventually".

> The problem is what happens when there isn't sufficient IPv4 to do dual
> stack.

that problem has many low hanging solutions, some of which mark andrews
gave in his response to your note.  one popular address allocation policy
proposal is reserving the last IPv4 /8 for use in IPv6 deployment, for
example as public-facing dual-stack-lite gateways.

which brings me to the subject of address allocation policies, and meetings
that happen periodically to discuss same.  one such address allocator is
ARIN (American Registry for Internet Numbers) and one such public policy
meeting is next week in toronto.  details of this meeting can be found at:


and anyone, not just from the ARIN service region and not just ARIN members,
can attend.  there are also remote participation options, see above web page.
Paul Vixie
Chairman, ARIN BoT

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