Date: Mon, 06 Aug 2012 00:49:29 -0700 From: Doug Barton <dougb@FreeBSD.org> To: Hiroki Sato <hrs@FreeBSD.org> Cc: jhay@meraka.org.za, svn-src-head@FreeBSD.org, svn-src-all@FreeBSD.org, src-committers@FreeBSD.org, emax@FreeBSD.org Subject: Re: svn commit: r238622 - head/etc/rc.d Message-ID: <501F7709.1080408@FreeBSD.org> In-Reply-To: <20120803.142847.874617321595545142.hrs@allbsd.org> References: <CAFPOs6pM8qrR72kOtZzO90wYembNrtzw7=ig-NSfudJZA7bp6Q@mail.gmail.com> <20120803.124305.1981901625663633450.hrs@allbsd.org> <20120803042301.GA78461@zibbi.meraka.csir.co.za> <20120803.142847.874617321595545142.hrs@allbsd.org>
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On 08/02/2012 22:28, Hiroki Sato wrote:
> John Hay <jhay@meraka.org.za> wrote
> in <20120803042301.GA78461@zibbi.meraka.csir.co.za>:
>
> jh> While you guys are here, may I add a request that we go back to prefering
> jh> IPv6 when IPv6 addresses are enabled. That is the way it was from FBSD-4
> jh> up to FBSD-8. 9 is a big POLA here.
Actually all that used to be needed was ipv6_enable. I modified the rc.d
code for this prior to 9-release to make it compatible with the old
knobs (aka, expected behavior), but hrs overruled me and installed his
version instead.
> jh> The world is past World IPv6 Launch
> jh> and I think people expect that if they configure IPv6 addresses, that
> jh> would be prefered. If you configure IPv6 addresses and do not want them
> jh> prefered, you are the odd one out and should have to do something.
I agree. My proposal was that if an interface is configured for IPv4 it
should get the same treatment for IPv6. That is, if it's set up for DHCP
in IPv4 then it should automatically do SLAAC/RA in IPv6; and if it's
statically configured in v4, the user should have to configure it in v6
as well (either with a static definition or by explicitly enabling RA).
I wanted to move to a model where you could simply say ifconfig_em0=auto
and have it DTRT.
> jh> Otherwise when in the future are we going to change it?
>
> IPv4-preferred was chosen as the default because difference of the
> loopback performance was large. I am a big fun to make FreeBSD
> IPv6-capable by default and prefer IPv6, but the concern was a
> possible negative impact for people who are using only IPv4.
Hiroki, you and Bjoern made the same argument over 2 years ago. Are you
saying that nothing has been done to improve this in that whole time? If
this is such an important problem, why hasn't it been addressed?
> So, can we change it for 10.X now? We cannot use "whether IPv6
> address is configured" because ::1 is always configured in GENERIC
> kernel. The change will be "IPv6-preferred if the kernel has INET6
> support".
Aren't those 2 ways to say the same thing? There is no v6 address
configured on lo0 if there is no INET6 in the kernel.
In the current regime I think it would be sufficient to prefer v6 if the
user has configured an interface with it (see below). I did this in my
version of the code that you reverted, so you can crib from that if you
need to.
> Preferring IPv6 addresses has needed a knob in rc.conf even in 4.x:
>
> 4.X:
> ipv6_enable="YES"
Until you introduced the changes in 9, it was not necessary to configure
the address if you were using RA. Now even with RA it's necessary to do
ifconfig_em0_ipv6="inet6 accept_rtadv"
> ipv6_ifconfig_em0="2001:db8::1 prefixlen 64"
>
> 9.X and later:
> ip6addrctl_policy="ipv6_prefer"
> ifconfig_em0_ipv6="inet6 2001:db8::1 prefixlen 64"
>
> and if we change the default to ipv6_prefer, ip6addrctl_policy= line
> will be unnecessary.
But it will still be necessary to configure the interface.
John,
In regards to your desire for this to work automatically, we're not
there yet. We don't currently have a good way to build v6 into the
kernel, and configure interfaces with it, but not actually *use* v6
unless we get a network. What you described was the end goal of the
changes I put in, which were ultimately reverted.
Doug
- --
I am only one, but I am one. I cannot do everything, but I can do
something. And I will not let what I cannot do interfere with what
I can do.
-- Edward Everett Hale, (1822 - 1909)
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