Subject: RE: ocean: do not boil

From: Margaret Wasserman <[email-masked]>
Date: Tue, 24 Sep 2002 10:19:28 -0400

Hi Hesham,

At 05:58 AM 9/24/02, Hesham Soliman (EAB) wrote:

>   > p2p applications can be designed to use intermediaries,
>   > just like SMTP and HTTP. If I was designing an apps
>   > protocol today, I would definitely make sure it could
>   > be relayed between address spaces at applications level.
>
>=> Are we in a position to mandate this?

We're not in a position to _mandate_ anything.  However, we are
in a position to make recommendations about the best way to resolve
certain scenarios.

Say we have a scenario that runs like this:

         HostA is an IPv6-only node in an IPv6-only network in SiteA.
         HostA wants to reach ServiceB which runs on HostB in SiteB, an
         IPv4-only service on an IPv4-only node in an IPv4-only network.

Now what are the possible solutions to that scenario?

We could say that the best solution for this scenario is to install
a NAT-PT-like box at the border of SiteA, modify the resolver in
HostA (or the DNS server for SiteA) so that HostA will receive special
IPv4-mapped addresses instead of A records for IPv4-only hosts,
insert special routes to send packets to those addresses to the
NAT-PT-like box, and translate traffic to those addresses from
IPv6->IPv4 at the border of SiteA.

We could say that the NAT-PT-like box should be installed at the
border of SiteB, AAAA DNS entries should be advertised for the
IPv4-only hosts within SiteB, routes should be advertised to cause
IPv6 traffic to those addresses to come to NAT-PT-like box on the
border of SiteB, and packets will be translated from IPv6->IPv4
at that border.

Or, we could simply suggest that, if people want to reach IPv4-only
services from a given host, they should support IPv4 connectivity to
that host.  This would mean installing a dual-stack on HostA and
providing IPv4 connectivity (perhaps via NAT if IPv4 address space is
an issue) within SiteA.

We can suggest any one of these solutions, and people are, of course,
entitled to ignore us.  Given the choice between these three, though,
the third one seems simpler and less prone to introducing new
architectural and application-level issues, since the IPv4 infrastructure
would be exactly the same as what many people are using today.

Margaret

---

From: "Alper E. YEGIN" <[email-masked]>
Date: Tue, 24 Sep 2002 18:43:55 -0700

> would be exactly the same as what many people are using today.

Shouldn't we also be considering how any of these choices effect the
overall IPv6 transition of the Internet? Gradually we'd like to see IPv6
replace IPv4, right? So, if we marry the existence of an IPv6 instance
to existance of a matching IPv4 instance, how are we going to see
Internet's transition to IPv6...  If we pick the 3rd choice, we cannot
really
have IPv6-only hosts. When can we have one? Maybe as soon as
IPv6 has a critical mass and some of those hosts declare IPv4 Internet
is not worth the access...?

This choice also keeps the pressure on the IPv4 address demand and
the complexity to handle them..

I think deployment of IPv6->IPv4 (IPv6 connecting to IPv4) will
expedite the IPv6 transition of the Internet... "Co-existence" of IPv6 in
the current Internet is the must-have first step, but "transition" of
Internet
to IPv6 is the ultimate goal.. (unless we want to live with IPv4 forever,
and create an alternate/parallel universe of IPv6..)

alper

---

From: [email-masked]
Date: Wed, 25 Sep 2002 11:33:32 +0900

>and create an alternate/parallel universe of IPv6..)

	it's just like we have transitioned from closed TSS systems like
	compuserve to IP.  we will eventually see services available only
	over IPv6, IPv4 services (as a collective means) become less attractive,
	and people will less motivated to maintain their IPv4 connection.
	then IPv4 will gradually cease.
	so yes, IPv4/v6 dual stack age could be very long.  it will take
	a long time until all IPv4-capable-and-configured devices go away.

	(speaking of codebase, IPv4 code will stay forever in the kernel.
	in fact, we still have ISO/CCITT protocol stack in NetBSD and such...)

itojun

---

From: Keith Moore <[email-masked]>
Date: Tue, 24 Sep 2002 23:02:04 -0400

> Gradually we'd like to see IPv6 replace IPv4, right? 

sometimes I think this is actually a non-goal.  or at least I think
it's more constructive to think in terms of migrating different
classes of applications separately. some apps will never run
on IPv4, and some apps may run on IPv4 essentially "forever",
even though the normal case may eventually to talk to them using
IPv4-over-IPv6 tunnels over an entirely IPv6 network.

Keith