Re: NAT64 in RA, draft-ietf-6man-ra-pref64

[David Farmer <[e-mail]>]

On Mon, Jul 8, 2019 at 10:49 AM Mudric, Dusan (Dusan) <[e-mail]>
wrote:

> > -----Original Message-----
> > From: Manfredi (US), Albert E <[e-mail]>
> >
> > -----Original Message-----
> > From: ipv6 <[e-mail]> On Behalf Of Mudric, Dusan (Dusan)
> >
> > > - How can DNS64 tell IPv6 only client the IP of IPv4 only client, and
> vice
> > versa?
> >
> > IPv6 to IPv4 should be straightforward, because it's a one-to-one
> > relationship. The other way around would normally not work,
> [Dusan] There is no solution for IPv4only client to reach IPv6only client?
>

I mostly say, so what! It is an unfortunate reality of today's Internet,
because of NAT44 and/or stateful firewall default deny inbound policy, many
times clients can't speak to other clients, be they IPv4 only, IPv6 only,
or even dual stack. Sometimes firewall traversal technologies can work
around this, also depending on the firewall traversal solution used
sometimes IPv4 only and IPv6 only clients will be able to talk to each
other.  My guess is that IPv4 only to IPv6 only firewall traversal would be
less effective than NAT44 client to NAT44 client firewall traversal, but it
is should still be possible in some cases.


> > but everyone
> > has been accustomed to that with IPv4 NAPT already.
> [Dusan] How IPv4 only users (e.g. Avaya IPv4 only phones) can be
> accustomed not to be able to call IPv6only users (like Apple IPv6 only
> phones)?
>

They may not be able to talk peer to peer. However, through a dual-stack
SIP or other proxies/session border controller, they could probably
complete a call.


> >The client behind the
> > NAPT initiates.
> >
> > > Is DNS64 server returning IPv4ony client address to IPv6only client,
> using
> > the A RR?
> >
> > The DNS synthesizes the IPv6 address, which has the IPv4 address
> > embedded in it.
> >
> > > - How can IPv4only client get the address of IPv6only client (or, it is
> > impossible for IPv4only client to get IPv6 address of IPv6only client)?
> >
> > That's clearly more difficult, which is why the normal course of action
> is for
> > the IPv6 client to initiate the session.
> [Dusan] What if IPv4only client needs to initiate the session to IPv6only
> client? What is the solution for that use case?
>

Many firewall traversal solutions should work in this case, but IPv4 only
client to client isn't guaranteed to work in all cases either.


> >
> > > - Do these IPv4 and IPv6 client addresses need to be pre-configured on
> the
> > translator and/or DNS64?
> >
> > For IPv4 to IPv6, if you must allow the IPv4 client to initiate the
> session, you'd
> > have to have preconfigure something.
> [Dusan] Where and how is this configuration done?
>
> >
> > Bert
>
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