Re: operationally (if not yet WG) related

[Erik Nordmark <Erik.Nordmark@eng.sun.com>]

> 
> >>"We recommend DNS administrators DO NOT use mapped IPv6 addresses with
> >>opcode 28 <type AAAA> resource records in ANY zone file."
> >
> >	I agree 120%.

I also agree with Bill's suggestion for DNS operation.

> 	more words:
> 	from what RFC2553 3.7 says, IPv4 mapped addresses are not supposed to
> 	appear on the wire.  they are OS-internal representation of IPv4 peers
> 	on top of AF_INET6 socket.  they are not supposed to appear in the wild
> 	like AAAA records.

I think it would make sense to figure out whether it makes sense to
extend the restriction on the IPv4-mapped address format to other places
where it would appear in essentially textual form.

While IPv4-mapped addresses are quite useful in the API I have not seen
any need to have them appear in textual format e.g. in configuration files.
Thus instead of having configuration files (or other textual literal addresses)
use ::ffff:a.b.c.d they should just use a.b.c.d.

It makes sense discussing the general (non-DNS specific) issue in ipng.
For example, I can envision getting implementors modify 
getnameinfo and inet_ntop to always present an IPv4-mapped address
as the IPv4 address i.e. without the leading "::ffff:" text.
That would help prevent these addresses appearing in undesired places
in the future.
(Of course, one could also entertain having getaddrinfo/inet_pton refuse
to *parse* such addresses but that might be more difficult to introduce
immediately.)

  Erik