On Tue, Nov 22, 2011 at 3:52 PM, Brian E Carpenter < brian.e.carpen...@gmail.com> wrote:
> 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. > > This is a distinctly different problem than the one that kicked off the link- local discussion. In the web browser case, you know the link-local destination address of the server a priori but it only has validity with respect to a particular link, and there's no way to indicate the zone index to the browser (assuming multi-homed client here). The once- existing capability was removed because there is no RFC support for it. The DNS case seems like a server-side issue. In the case of link- local adresses stored in AAAA records, the zone index would seem to indicate the corresponding interface with respect to the *server* (assuming a multi-homed server here). What's more, the DNS server would need to keep track of the interface on which the query arrived and only respond with a link-local address if the client and server are on the same interface. Some additional observations: - If you want to stay with link-local addresses then perhaps multicast DNS is the best solution for you. - If you want to stay with unicast DNS, then ULAs have the advantage of being routable and the problem goes away. - If you want to stay with link-local addresses *and* DNS, then perhaps you need to engage dnsext WG to discuss the server-side issues. -K- Brian > > > > > 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 > local > > or if interface information is lost in some other way. > > > > >
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