Re: Link-local IPv6 addresses in the DNS

[Mark Andrews <[e-mail]>]

In message <[e-mail]>, Brian E Carpenter writes:
> On 2011-11-23 05:34, Philip Homburg wrote:
> > In your letter dated Tue, 22 Nov 2011 14:30:03 +1100 you wrote:
> >> On a related issue to link locals in URI's, we don't currently have
> >> a good method of supporting link locals in the DNS.  Sure we can
> >> add them as AAAA records but they are essentially useless as the
> >> scope information is lost.  People keep saying use LL for disconnected
> >> but it just doesn't work without more support.
> 
> Other people keep saying "use ULA for disconnected". The fact
> that you can put ULA into (er, local) DNS without any fancy
> stuff is a distinct advantage.
> 
> IMHO link-local should be used only for bootstrapping a host and
> for diagnostic purposes. I guess I could statically configure a
> printer on fe00::a%1 if I really had no choice.
> 
>    Brian

ULA has similar scope issues.  It's just that the OS don't knock
you over when you do bind(), connect(), sendto() and sendmsg()
without scope information.  You can avoid using non local ULA with
the same filtering mechanisms.

> > For disconnected operation, why not have getaddrinfo fill in the scope?
> > Just set it to the interface over which the DNS reply arrived. 
> > 
> > I have to admit that this may become a bit tricky if the DNS resolver is lo
> cal
> > or if interface information is lost in some other way.
> > 
> > 
-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
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