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

[Juliusz Chroboczek <[e-mail]>]

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.

-- Juliusz