[arin-ppml] IPv6 adoption, map-encap for IPv4?

Robin Whittle rw at firstpr.com.au
Thu Jun 12 23:00:58 EDT 2008

Hi Paul,

In "Re: [arin-ppml] Portable address space vs. IPv6 auto-numbering"
you wrote:

>>> while i am not a member of RRG, if the question is drawn as
>>> clearly as that, my position would be, forget about IPv4.
>>> the internet will have many more than 2^32 devices connected
>>> to it simultaneously within our lifetimes, and i think we
>>> should preserve the option of not using NAT in future
>>> generations.
>>> therefore IPv4's growth has a glass ceiling formed by its
>>> address size, and any effort that's put into growing its
>>> routing table has a fixed return.
>> OK - quite a few people on the RRG agree with you on this.
>> Here is a more nuanced version:  ...
> i think that what quite a few people on RRG might be in agreement
> with is the first qualified statement i made, "...forget about
> IPv4."  however, the qualification is important: "if the question
> is drawn as clearly as that," which it sounds like it isn't.

The text being debated in the RRG is from co-chair Tony Li and is
quite short:


My understanding of this is that it would make it acceptable for the
RRG to work on the IPv6 problem alone, and not the IPv4 problem.  On
PP ML recently, I think Tony expressed a desire to solve the IPv6
routing scaling problem by change IPv6 (protocol, stack and I assume
applications) to support GSE, and not work on IPv4 at all.

I suggested a longer and more detailed alternative - solving the
IPv4 problem soon and then taking more time with IPv6, which has
more technical alternatives and less backwards compatibility


Tony's text has received more support than mine, though my text was
supported entirely by Bill Herrin (TRRP map-encap developer) and the
APT (map-encap) team supported fixing both IPv4 and IPv6 with the
same approach.  The remaining map-encap developers - the LISP team -
haven't commented on my text, but my understanding of their earlier
comments is that they want to fix both the IPv4 and IPv6 problems.
   So I understand that the map-encap developers in general want the
RRG to recommend a fix for IPv4.

> furthermore, what i mean by "fixed return" is that it's
> economically damned: the more effort we put into it the more
> expensive that effort will turn out to have been.  i don't know
> if the RRG folks are looking at this as an economics proposition
> but if not, there isn't really any necessary relationship between
> what i said and what they might, under different and/or synthetic
> circumstances, agree with.

The best place to debate Tony's proposal is the RRG list.

Naturally, the more effort the more cost.  My best guess is that a
great deal of effort will be put into keeping IPv4 going, because
IPv4 space will remain the only way to provide Internet services
which people find acceptable.  IPv6-only services simply don't do
what most end-users want and need.  David Conrad listed some major
reasons why most end-users and ISPs don't want IPv6:


not least because "c) Very few of the applications end users want to
run support IPv6".  While I accept what I am told about major
browsers and email programs working with IPv6 - and some games and
perhaps P2P file sharing programs - I would put it another way:

   A high a proportion of ordinary business and home end-users
   would find some application would not work as expected in an
   IPv6-only service, and/or would find that some site, some service
   etc. was not available to them.  This would cause many or most
   of them (probably the great majority) of them to be too
   dissatisfied to continue the service when they could get an IPv4
   service from a competitor.  Also, for those who remained, the
   ISP would face excessive support costs.

> i'm not just picking nits -- your "more nuanced version" does not
> represent my view correctly, it is not a restatement of any
> position i've had nor of one i can agree to.

My "more nuanced version" was an attempt to better state my
position, which I know is very different from yours.  I wasn't
expecting you to agree, but was trying to draw out the differences
in our perspectives.

>> ... Many IETF folks have had unrealistic optimism about
>> end-users wanting or needing IPv6 for over a decade. While I know
>> that IPv4 with NAT etc. falls a long way short of the ideal, I
>> still think many IETF folks are unrealistically optimistic about
>> IPv6 adoption in the next 10 years. I think there are plenty of
>> coping mechanisms for keeping IPv4 tolerable for most users in
>> that time frame and probably beyond - and these will be cheaper
>> and better for ISPs than trying to sell an IPv6-only service.
> while on the one hand i completely disagree, the bigger issue is,
> you're just saying what you think, here, whereas in your two
> previous articles you shared facts.

Apart from quoted text, everything I write is based on what I think.

I think you are most likely to identify my thoughts as facts when
you agree with them.

What I wrote above is about the future.  We have no facts about the
future.  However, I can reliably inform you that it is a fact that I
believe this about the future!

>> The transition mechanisms are not there. The IPv6 Internet
>> doesn't connect properly to the IPv4 Internet. People like the
>> IPv4 Internet because everyone is reachable via it.
> these are plain facts and i agree. (i wanted to agree to
> something here.)

Yes, I prefer to agree if it is all possible.

> as to optimism, jean camp showed some S curves in denver
> describing adoption of technology, and while a lot of folks didn't
> understand them, they were well argued and well reasoned, and they
> give *no* cause for optimism wrt IPv6. so, if provable pessimism
> about IPv6 were an argument in favour of prolonging the lifetime
> of IPv4, you'd need look no further than elmore/camp/stephens:
> http://weis2008.econinfosec.org/papers/Elmore.pdf

Thanks for pointing me to this.  I have only dipped into the text.
Figure 5 shows two S curves of adoption of IPv6 as a proportion of
ASes.  The "optimistic prediction" seems to reach 98% in 2011.  The
"best prediction" S-curve shows only a few percent in 2011, and
seems to reach 50% around 2040.  Figure 1 looks bleaker still, but
does not take account of IPv4 address depletion.  The faster and
slower rising curves are the result of increasing or decreasing the
"follower coefficient" by one standard deviation.  Figure 5 is based
on the IPv6 adoption rate after the drop caused by the end of 6bone.

> alain durand's current plan is to native V6 to their customer
> edge and backbone, and use native V6 to carry NAT'd V4, and thus
> get provide stack to the comcast customer base. apple and
> microsoft, as well as every IP-capable device designed or
> manufactured in japan, as well as most f/l/oss software,
> will all use native V6 if it's present.

OK, but I think this falls a long way short of what end-users want
and need in the next few years.

Do the major PC firewalls and anti-virus programs work fine over
IPv6-only?  What about the various IM programs, AIM, Yahoo Chat etc.
Searching adobe.com for IPv6 turns up some pages which suggest that
at least some of their apps use IPv6.  There's a bunch of shareware
and freeware that people like to use.  I wonder how much of that is
ready for IPv6 only services.  There are really strong reasons for
keeping XP and avoiding whatever else Microsoft wants us to use - so
it is a non-starter to expect customers to switch from XP.  That
would need a fix because I understand its DNS relies on IPv4.

I figure most printers etc. only support IPv4, so the customers are
going to be running IPv4 on their LANs and IPv6 to the outside
world.  I haven't tried this, but I imagine the average user is a
long way from being able to use IPv6-only, without noticing any

What about VoIP boxes and programs.  How many of these are ready for
IPv6 at all and how many can actually do calls and conferencing via
some gateway to IPv4 without any user intervention of inconvenience?

> there's a very real deployment scenario involving islands of this
> kind of dual-stack, followed by address space shortages and/or
> explosive routing table deaggregation, followed by heightened,
> agitated capital investment in more dual-stack because
> it's a way to avoid the worst pain of the shortages/explosions.

I think this optimism about early migration to IPv6-only is based on
an unrealistically bleak notion of how difficult it will be to make
much better use of IPv4 space in the next decade or two and on an
unrealistically rosy view of how many end-users won't be troubled by
apps and various Internet services, not least most web-sites, not
working via an IPv6-only service.

I don't see how you hold this optimistic view when you agree with
these statements as facts:

>> The transition mechanisms are not there. The IPv6 Internet
>> doesn't connect properly to the IPv4 Internet. People like the
>> IPv4 Internet because everyone is reachable via it.

>> I think a scalable IPv6 could be prepared, which sounds like
>> heaven to many IETF people (though I still think 128 bits is 64
>> too long) - but the main population of end-users wouldn't care,
>> since it is a different planet with almost none of their friends
>> on it yet.
> i think we're going to see IPv6 routing table bloat earlier than
> RRG's work could possibly complete,

But this is not yet a fact :)

> and that that's the real race here, and that any time spent
> prolonging IPv4's doddering old age with double- and triple-NAT is
> a dangerous distraction. the internet is not just the web, and we
> can't go on building new kinds of applications if everything has
> to be some kind of NAT or map-encap or ALG or proxy. IPv4 is
> headed for end-of-life. let's move on.

I think our discussion nicely illustrates two widely different views
about IPv6 adoption in the next five years.

If someone got a bunch of ordinary home users this year, and put
them on an IPv6-only service with state of the art NAT-PT or
whatever, and then found that 90% of them or more didn't notice much
difference, and didn't make more than one or two support calls, then
I would modify my views.

Comcast and maybe other providers have a lot riding on this
IPv6-only service model.  If it is so feasible, I would have thought
they would have done some actual trials with real users by now.
Alternatively, they might have done a careful study of exactly what
a hundred or so home and SOHO customers do with their PCs and
Internet services over a period of 3 months, and then recreated a
representative subset of this in the lab - to see how it flies with
their IPv6-only service.

There is a discussion on the RRG list about how ordinary end-users
might, and to some small extent are, adopting IPv6 such as via a
tunnel broker service, to give their home services a stable place on
the Net, albeit the IPv6 Internet.

However, many DSL modems support uPnP, and this already provides an
automated and robust method by which applications on PCs can punch
holes in the modem's NAT and so have a reasonably stable publicly
accessible UDP or TCP port.  This means they can accept incoming
communications, run a web server, game server, fully functional P2P
client/server etc.  Various dynamic DNS services makes these servers
etc. easily accessible and apparently stable to other end-users.
So it is not as if this IPv6 approach is the only way of getting a
stable public IP address for most users who are on single IP address
DSL services with NAT in the modem.

 - Robin             http://www.firstpr.com.au/ip/ivip/

  - Robin

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