[governance] IPv4 - IPv6 incompatiblity (was Re: Towards Singapore)

John Curran jcurran at istaff.org
Fri Jun 17 07:27:37 EDT 2011

Paul -
  Excellent points.  I also go to great length to stress how the protocols
  that we use everyday (such as http for web and smtp for email) run without
  change over IPv4 and IPv6 equally well and that this interoperability was
  an explicit design goal.  Further, we planned that IPv4 and IPv6 services
  can run together over your existing Internet equipment at the same time.
  The petro and electric cars on the same roads is a good analogy; I'm sure
  I'll be making use of it in explanations going forward.


On Jun 17, 2011, at 2:44 AM, Paul Wilson wrote:

> Norbert, Izumi, all,
> Unfortunately, this "backwards compatibility" issue has been widely misunderstood and misrepresented.  Personally, I'm tired of dealing with journalists who have been told that v4 and v6 are like "oil and water" and don't mix, and who ask if IPv6 users need to buy different services, different cables, different equipment, different email address, etc etc to stay online.  It takes quite some explaining to undo that bundle of misconceptions!
> Yes, at one level v4 and v6 are incompatible, naturally, because they are Different Protocols; but above and below the IP protocol level, they are perfectly "compatible" - they run side by side on the same wires, through the same equipment, and on the same services as each other; and they support the same applications, which work in the same way, to the extent that users don't even need to know.
> I've promoted an analogy between the v4-v6 transition and the transition from oil to electricity in our transport system.  And it works for this discussion as well:  you don't try to plug your volkswagon beetle into the mains - because oil and electrons certainly don't mix - but that old car is still perfectly "compatible" with the latest electric one: it drives on the same roads, uses the same rules and the same controls; and carries the same passengers in the same way.
> As for "backward compatibility" I suggest to be careful what you ask for here, because that is always a temporary benefit, and often a long-term curse. MS Windows users have suffered vast costs and complexities for many years, just so that a few MS-DOS applications could keep running; and then there's the old  QWERTY keyboard.
> On the other hand, we might remember the complaints surrounding Apple's change to OSX, a completely new and incompatible operating system (well, being based on Unix, a completely OLD operating system).  But does anyone care about that any more?  No, it's been properly forgotten, just as IPv4 will be when the big transition is done.
> I admit to blissful ignorance of the blow-by-blow disputes and politics of the development of IPNG in its various early flavours; and I don't care much to go back there.  But I can certainly imagine that if IPv6 were shackled with tricks to have it interconnect directly with IPv4, at the IP level, then in a few years time, and for decades afterwards, we'd all be cursing the developers for their shortsightedness.
> My view is that the only significant sin of the IPv6 developers, at least the only one which is relevant here, is to have underestimated the coming success of the Internet.  It is that success which allowed the Internet to grow so vast and to become so very cheap, the major factors which conspire to make the IPv6 transition much harder than anyone thought.
> Thanks.
> ________________________________________________________________________
> Paul Wilson, Director-General, APNIC                      <dg at apnic.net>
> http://www.apnic.net                                     +61 7 3858 3100
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