[arin-ppml] Portable address space vs. IPv6 auto-numbering

[Robin Whittle]

I am replying to Paul Vixie and Ted Mittelstaedt.

Paul Vixie wrote:

> robin, thanks for this and for yesterday's message on this thread

http://lists.arin.net/pipermail/arin-ppml/2008-June/010984.html

> your explainations of the outstanding issues are clear and concise
> and i hope you will blog them somewhere so that this mailing list
> won't be the only permanent record of what you said.

Thanks very much!  Nonetheless we disagree about whether to fix the
IPv4 routing scaling problem.

I linked to this thread from the "Recent Developments" section of
the homepage for my Ivip (Internet Vastly Improved Plumbing)
map-encap proposal:

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

> most important thing i've learned is that RRG hasn't got consensus
> on whether or not to try to save IPv4.  you wrote:
>
>> If the RRG decides that it doesn't need to solve the IPv4 routing
>> scaling problem, then there is plenty of time to come up with an
>> IPv6 solution with a wider variety of potential techniques and
>> fewer backward compatibility reasons than would be the case for
>> an IPv4 solution.
>
> 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:

  If the RRG decides it doesn't need to fix the IPv4 routing
  scaling problem, then it can concentrate its energies - and
  the IETF's, if the IETF accepts the RRG's recommendation - on
  the much less urgent IPv6 scaling problem.

  IPv6 has many more technical possibilities for solving the
  problem, primarily due to its longer address length and much
  lower installed base.

  If the RRG/IETF doesn't care about the IPv4 routing scaling
  problem, then it probably has many years to solve the IPv6
  problem, because I can't see how mass migration to IPv6 is
  going to happen in the next decade.

  However, this seems like a high-pressure, high-risk venture.

  While one planet burns, the expeditionary force is supposed
  to be preparing another, significantly incompatible, but
  ultimately better planet.  I would rather a more relaxed
  mission timetable:

  I would rather fix the IPv4 problem ASAP and have more time
  to prepare a lasting alternative, especially something with
  greater ease of migration from IPv4, which means a much better
  means of communicating with the IPv4 Internet than is currently
  possible with IPv6.

NAT-PT has been buried and the replacements - NAT64 and DNS64 -
are at a very early stage of development:

http://tools.ietf.org/html/draft-ietf-v6ops-nat64-pb-statement-req-00
http://tools.ietf.org/html/draft-bagnulo-behave-nat64-00

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.

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.

Ted Mittelstaedt 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.
> 
> Standard road lane width on a modern US highway is determined
> by the width of the butts of 2 horses.  This dates back oh,
> a couple thousand years.

For the sake of the argument, I won't dispute this.

> Is standard auto and road width optimal?  I don't know.  I do
> know, though, that a hell of a lot of people have died in
> SUV rollover crashes that would have not happened if the width
> of their vehicle was, say, the width of 3 butts of horses.

Time to re-introduce the 1959 Chevrolet.  Nice and low and with
narrow window-door "A pillars" so there is no obstruction of vision.

> Backwards compatability is not always smart, and can even
> kill people.  Think unintended consequences.

<off-topic>

  Yes.  Folks in the USA drive on the wrong side of the road - in
  part, after copying the French practice of driving on the right to
  be like the proletariat who swapped from walking on the left to
  walking on the right to be safe from the landed gentry who were
  driving their carriages on the left.  Walking  on the left is the
  natural approach - most right-handed people can have their dagger
  hand ready to tackle an oncoming attacker:

http://users.pandora.be/worldstandards/driving%20on%20the%20left.htm

  This causes crashes when North Americans make understandable
  mistakes driving in countries where we still drive on the correct
  side.

</off-topic>

Sure, but IPv6 has not been needed or wanted by the vast majority of
ISPs and end-users in the 12 or so years since its inception.

Do you think it would be best to soup it up for scalable routing
while IPv4 festers, or to fix IPv4 and take a longer, more relaxed,
time to do a better job of improving IPv6 and making mass migration
more practical?

You might be interested in the possibility of applying GSE:

  http://tools.ietf.org/html/draft-ietf-ipngwg-gseaddr-00

to IPv6 (while not fixing IPv4), as is being discussed on the RRG:

http://psg.com/lists/rrg/2008/maillist.html
http://www3.tools.ietf.org/group/irtf/trac/wiki/RoutingResearchGroup

  - Robin