"DNS-4to6 automatic mapping" - No more DNS-ALGs & 6then4 DNS queries

["despres.remi" <despres.remi@laposte.net>]

Currently proposed solutions for IPv6-only to IPv4-only connectivity
include some specific DNS processing, at the application layer, outside
the DNS itself : DNS-ALGs in various NAT-PTs; duplicated DNS queries
(IPv6 and IPv4) in IPv6-capable applications and/or stacks).

The result is significant complexity (with timers in particular),
additional traffic across the network, and potential operational
problems with DNS ALGs.

Also, one can see on the Web recommendations that IPv6 capable
applications, Firefox in particular, should DISABLE IPv6 (!!!).
The reason is that DNS queries to reach IPv4-only hosts are in two steps
instead of one : one for an IPv6 address, failing most of the time, and,
only then, one for an IPv4 address, succeeding most of the time.

All this is UNFORTUNATE but, being avoidable as shown below, IMHO SHOULD BE
AVOIDED in the future).

For this, let's specify that a next release of the DNS sotware (BIND and
others) will have to include a DNS-4to6 AUTOMATIC MAPPING.
With it, an IPv6 RR is automatically created, within the DNS, for each
existing IPv4 RR, using for this the *mapped address format* of RFC 2373.
There is no scalability issue, this being a "one-time" processing.
Deployment of this DNS automatic mapping is simply the deployment of a
new release of the DNS software (a fairly wellknown process).

Then :
- IPv6-only applications on dual stacks will work using IPv4 transport
without knowing about it.(The answer to their IPv6 request is in fact an
IPv4 address, in the format recognized by the lower layer dual stack to select IPv4 transport).
- IPv4-IPv6 applications will no longer need a second DNS query to reach
IPv4-only hosts.

This seems to me as simple and effective as a Columbus egg.
If this is wrong, please describe why.
And if this is right, how could this proceed in Vancouver? (I cannot be
there).

Regards.

Rémi


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