From owner-freebsd-ports  Fri Jan  7  7: 3:10 2000
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To: asami@FreeBSD.ORG
Cc: freebsd-ports@FreeBSD.ORG, committers@FreeBSD.ORG
Cc: sumikawa@ebina.hitachi.co.jp
Subject: Re: IPv6-enable ports
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asami> That sounds fine, but what about packages?  They will all be built
asami> without IPv6 support, right?

I think It should synchronize default kernel configuration. If kernel
is enabled IPv6 in default, the packages should be build with IPv6
support.


asami> Or is IPv6 support downwards compatible with IPv4?  In that case I can
asami> set USE_INET6 in the build environment and be done with it.

Almost of applications work fine, but downwards compatibility is
depends on each implementations in general.

In IPv4/IPv6-mixed world, a typical host is assigned several IPv4/IPv6
addresses. In this case, applications must try to connect all of
address of the host until it make a success as below.

foreach an address from candidates {
	try to connect an address;
	if (failed)
		next;
	else
		break;
}

This is too general explanation. Getaddrinfo() loop is used
concretely. See, http://www.kame.net/newsletter/19980604/.

However, it is possible that some of applications give up in first
trying. These programs quit right now, when a non-IPv6 kernel fails to
connect to an IPv6 host. It will be inconvenience for IPv4 users.

It's a kind of bug. But many programers have no experience of address
family independent programming.


Anyway, this releasing discussion is another issue, I believe. I'll go
ahead.

---
Munechika SUMIKAWA @ KAME Project / FreeBSD.org


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