Re: [homenet] In-network connectivity and HNCP: IPv6 ULA

I think the local ULA should be used for all intra-ULA connections. We had
a debate about this about four years ago, and apparently the text in the
HNCP spec reflects the outcome of that discussion, but I think we
understand  the problem better now and we should fix this. The current SHNA
doc requires the dnssd naming implementation to filter out GUAs when
answering requests on the local networks. THis was intended to ensure that
internal connections would survive the loss of the GUA.

On Thu, Jul 19, 2018 at 7:09 AM Brian E Carpenter <
brian.e.carpenter@gmail.com> wrote:

> On 19/07/2018 21:57, Juliusz Chroboczek wrote:
> > I've re-read Section 6.5 of 7788, and it looks like I was wrong.  Sorry,
> > I should not be writing technical mails in the middle of the night.
> >
> > As far as I can tell from the wording of 6.5:
> >
> >   - creating ULA is SHOULD if there's no global IPv6, MUST NOT otherwise;
> >   - creating private IPv4 is MAY if there's no global IPv4, MUST NOT
> otherwise.
> >
> > If my reading is correct, that sucks.  I don't see how the MAY can be
> > implemented, since there's no obvious way to distinguish global from
> local
> > IPv4, and if you don't implement the MAY, then you'll lose local IPv4
> > whenever your IPv4 provider has a glitch, as you described.
> >
> >> if you have a connection over IPv4 and suddenly your IPv4 network is
> >> deconfigured, your connection will hang.
> >
> > The point Brian and I are trying to make is that you should have no
> > intra-Homenet IPv4 traffic -- your applications should prefer IPv6 to
> > IPv4, and and there should always be IPv6 in your Homenet.
> >
> > Unfortunately, our point is made moot by the first MUST NOT above, since
> > the ULA becomes deprecated whenever there's global IPv6.
>
> Yes, that should perhaps be revisited. But deprecated means: not to be used
> for *new* connections, which shouldn't kill existing connections.
>
>    Brian
>
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