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Hi Takeuchi-san,
On Wed, Aug 04, 2010 at 12:13:24AM +0900, Sohgo Takeuchi wrote:
>
> Hi simon,
>
> From: Simon Horman <horms@xxxxxxxxxxxx>
> |
> > On Mon, Aug 02, 2010 at 06:35:49PM +0900, Sohgo Takeuchi wrote:
> >>
> >> Hi,
> >>
> >> I have been working on improving IPv6 support of ldirectord
> >> for a few weeks. I would like to hear your opinion or ideas
> >> about how to write ldirectord.conf.
> >
> > A tricky topic, thanks for thinking it through.
> >
> >> Q1. Should ldirectord support an IPv6 hostname in ldirectord.conf?
> >>
> >> A manual of ldirectord says that a hostname can be written
> >> in "virtual", "real", "fallback" and so on. Current
> >> implementation of ldirectord handles the hostname as only
> >> IPv4. It partially supports IPv6, and can write only IPv6
> >> addresses. But it does not have a way to write a hostname as
> >> IPv6. Because there is no way to distinguish between IPv4
> >> and IPv6. Should ldirectord support an IPv6 hostname in
> >> ldirectord.conf?
> >>
> >> Q2. If the answer of Q1 is yes, how do you want to write?
> >>
> >> [Candidate 1] Adding a new keyword like a "ipversion".
> >> A default value of "ipversion" is 4 (IPv4).
> >>
> >> fallback=fallback.example.com
> >> fallback6=fallback.example.com
> >> virtual=virtual.example.com:daytime
> >> real=real1.example.com:daytime gate
> >> real=10.10.10.10:daytime gate
> >>
> >> virtual=virtual.example.com:daytime
> >> ipversion=6
> >> real=real1.example.com:daytime gate
> >> real=[2001:db8::10]:daytime gate
> >>
> >> This way cannot handle a global "fallback" variable. We must
> >> have a way to distinguish between IPv4 and IPv6 when a
> >> hostname is specified in the global "fallback" variable. To
> >> achieve this, there is a way to add a new variable of
> >> "fallback6". Any other good ideas?
> >
> > This "fallback" problem seems to be the most difficult issue.
> >
> >> [Candidate 2] Adding new keywords of "virtual6" and
> >> "fallback6".
> >>
> >> "virtual6" is an IPv6 version of "virtual". If a hostname
> >> and an IP address are specified in the "virtual6" line and
> >> in its section, they are treated as an IPv6 address and the
> >> hostname will be resolved into an IPv6 address.
> >>
> >> "fallback6" is just a global variable. It cannot be
> >> specified in a virtual section. If no "fallback" in a
> >> "virtual6" section is defined, the variable of "fallback6"
> >> will be used. If "fallback" in the "virtual6" section is
> >> defined, it is treated as an IPv6 address.
> >>
> >>
> >> fallback=fallback.example.com
> >> fallback6=fallback.example.com
> >> virtual=virtual.example.com:daytime
> >> real=real1.example.com:daytime gate
> >> real=10.10.10.10:daytime gate
> >>
> >> virtual6=virtual.example.com:daytime
> >> real=real1.example.com:daytime gate
> >> real=[2001:db8::10]:daytime gate
> >>
> >> This way breaks a backward compatibility. Current ldirectord
> >> can write an IPv6 address in a "virtual" line. But this way
> >> cannot.
> >
> > I'm not particularly concerned about backwards compatibility here,
> > IPv6 for ldirectord is pretty green.
>
> That's good.
>
> >> [Candidate 3] Completely separate IPv4 and IPv6 using
> >> "hoge6" keywords.
> >>
> >> Adding new keywords which denote IPv6. These keywords can
> >> handle IPv6 only and have a name "hoge6".
> >>
> >> fallback=fallback.example.com
> >> fallback6=fallback.example.com
> >> virtual=virtual.example.com:daytime
> >> real=real1.example.com:daytime gate
> >> real=10.10.10.10:daytime gate
> >>
> >> virtual6=virtual.example.com:daytime
> >> real6=real1.example.com:daytime gate
> >> real6=[2001:db8::10]:daytime gate
> >> fallback6=localhost:daytime
> >>
> >> This way is very similar to [Candidate 2]. But it is
> >> consistent and easy to read. A demerit is a bit redundant?
> >
> > I like candidate 3. Yes, it is redundant, but it is also very clear
> > and consistent.
>
> Yes.
>
> I have implemented [candidate 3]. Now it works good.
Great, once you've finished your testing please post the patch.
> > N.B: I think that all of the proposals would fwmark services without
> > any extra magic.
>
> Oh, thank you. I have not considered fwmark. I think so too as
> you say.
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