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To: Guido van Rooij <guido@gvr.org>
cc: "Jordan K. Hubbard" <jkh@zippy.cdrom.com>,
        Andreas Klemm <andreas@klemm.gtn.com>, Eivind Eklund <eivind@yes.no>,
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In-reply-to: guido's message of Thu, 03 Dec 1998 19:10:01 +0100.
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Subject: Re: Can we just come to a decision on IPv6 and IPSec? 
From: Jun-ichiro itojun Itoh <itojun@iijlab.net>
Date: Fri, 04 Dec 1998 11:10:51 +0900
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>As an end user on a IPV6 system, when I do telnet foo.bar.org,
>the resolver will try if there exist an AAAA record for that host and
>talk IPV6 directly. When no such record is available, it will return
>an IPV6 mapped address (if I recall the terminology right). In that case,
>the address (again, if my memory serves me right) 
>::ffff:a.b.c.d is returned and the kernel can automatically decide that
>thta is a mapped address and put the packets to the ipv4 stack on the system
>(with address a.b.c.d) all transparent to the end user.
>
>It seems the WIDE stack can not do this (at least not now). They
>have something called 'faith' which supposedly handles this from
>userland but I think this should be handled in the kernel.
>
>I think handling this transparently is a key issue in the ipv4->v6 migrattion.

	I believe it is not.  The key point is, applications must be updated
	to be protocol family independent.  They should use getaddrinfo()
	instead of gethostbyname2().

>Does anyone know:
>1) If WIDE will deal with this in a later stadium?
>2) What the INRIA stack does?

	I don't remember correctly (as I don't use mapped address frequently),
	but if you have KAME on FreeBSD 2.2.7, some code should come with the
	kit.  There should be environment variable or flag in _res structure
	for controlling resolver's behavior.

	One thing we don't implement intentionally is automatic tunnelling
	(packets to ::10.1.1.1 automatically tunnelled over IPv6-over-IPv4
	tunnel to 10.1.1.1).

itojun

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