Subject: RE: (ngtrans) Last call on draft-ietf-ngtrans-dns-ops-req-02.txt

From: "Christian Huitema" <[email-masked]>
Date: Mon, 22 Oct 2001 07:45:33 -0700

> > Again, I'd say "no".  For the next very many years (unless something
> > unexpected happends) we'd be able to manage just fine with
dual-stack.
> 
> mandating a dual-stack on all v6-capable hosts might be an approach.
but
> i suspect it will not be acceptable in some application/vendor
domains.

If an IPv6 only host wants to resolve a name that is served only by IPv4
capable DNS servers, it can send the request through a protocol
translating NAT (NAT-PT), and it will receive the response. There is an
operational issue, the fact that the current NAT-PT specification
mandates an "application layer gateway" treatment of DNS packets,
automatically translating A records into AAAA records; I find that a
poor trade-off between convenience and robustness; we may need to
revisit the issue. Nevertheless, NAT-PT should provide a generic
solution for "v6 hosts discovering v4 hosts."

The opposite problem, v4 only hosts discovering services provided in v6
only domains, is somewhat harder to solve. Indeed, at some point it will
become impossible to solve simply by address translation, since 2^32 <
2^128.

-- Christian Huitema

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From: Keith Moore <[email-masked]>
Date: Mon, 22 Oct 2001 15:04:47 -0400

> translating NAT (NAT-PT), and it will receive the response.

and there are several other ways of providing an equivalent service - such 
as by going through a DNS cache that speaks both IPv6 and IPv4. 

but it sounds like you are saying that the v6 client has the burden of providing
access to v4-only DNS servers, which doesn't sound right to me.

Keith