Subject: RE: comments on draft-durand-v6ops-assisted-tunneling-requirement s-00 .txt

From: "Karim El-Malki (HF/EAB)" <[email-masked]>
Date: Thu, 15 Apr 2004 19:39:40 +0200

>>
>> There are no NATs in mobile phones today since there is no use
>> for them and I sure hope never to see them. I think most people
>> would agree.
>
>Let me disagree.
>The scenario is a remote location or road warrior where the only 
>possible/realistic
>connectivity is through 3GPP/3GPP2. That may be an intermittent case 
>when 802.11
>is not available.
>I'd like to get a 3GPP network attachment on a computer 
>(PCMCIA/PCI/USB/Bluetooth...)
>or 802.11 access point and run a NAT there. It would act as a router 
>for the rest of my network.
>Now, any device within my network that desire to get IPv6 connectivity
>will have to go through that NAT.

You wouldn't need or want a NAT for that.
We are recommending that there should be IPv6 support (native
if possible otherwise tunnelled) by the 3GPP/2 operator. That's
the essence of the 3GPP analysis draft. So you can make your
terminal/laptop into an IPv6 mobile router (tunnelling or native
to the 3gpp/2 operator) and not get into the NAT headache. Since
there is a better solution than NAT I think we should use it.

/Karim

---

From: Alain Durand <[email-masked]>
Date: Thu, 15 Apr 2004 10:43:46 -0700

> You wouldn't need or want a NAT for that.

Yes I want it for my IPv4 connections.

> there is a better solution than NAT I think we should use it.

Of course, but I though we were talking about the case where the 3GPP
ISP was not (yet) offering IPv6 service.

	- Alain.

---

From: Fred Templin <[email-masked]>
Date: Thu, 15 Apr 2004 10:55:48 -0700

> Yes I want it for my IPv4 connections.

I'm OK with this, as long as you clearly distinguish
"IPv4 connections" from IPv6-in-IPv4 tunneling.

Fred
[email-masked]

---

From: Alain Durand <[email-masked]>
Date: Thu, 15 Apr 2004 10:59:43 -0700

> "IPv4 connections" from IPv6-in-IPv4 tunneling.

??? Please elaborate.

	- Alain.

---

From: Fred Templin <[email-masked]>
Date: Thu, 15 Apr 2004 11:16:35 -0700

>> "IPv4 connections" from IPv6-in-IPv4 tunneling.

Only that, from the perspective of IPv6-in-IPv4 tunneling, it
would be nice if any "NATs" behaved more like an ND Proxy.

This would not be the same thing as an "IPv6 NAT", which
I hope we will never see.

Fred
[email-masked]

---

From: Alain Durand <[email-masked]>
Date: Thu, 15 Apr 2004 11:40:58 -0700

> I hope we will never see.

Note that I'm not advocating for IPv6 NAT here. I'm saying that
IPv4 NAT is almost everywhere and during the transition to
IPv6, in the phase where the ISPs do not yet support full
native IPv6 in the access network, we must take into account
that IPv4 NAT may be in the way.

	- Alain.

---

From: Alain Durand <[email-masked]>
Date: Thu, 15 Apr 2004 11:59:51 -0700

> would be nice if any "NATs" behaved more like an ND Proxy.

Essentially, you are saying it would be better to use the IPv4 NAT box 
as
your v6 access router.
I agree.
Except that it may not always be possible.

	- Alain.

---

From: Alain Durand <[email-masked]>
Date: Thu, 15 Apr 2004 13:01:01 -0700

On Apr 15, 2004, at 12:04 PM, Fred Templin wrote:

>  All I'm saying is that explicit NAT traversal
> mechanisms should be used only as a last-resort, and unencumbered
> IPv6-in-IPv4 tunneling (or, better yet, native IPv6) should be used
> instead whenever possible.

Once again we are in agreement. This is absolutely compatible
with section 6.3:

6.3 NAT Considerations

    The assisted tunnel established by the protocol to be designed must
    work with the existing infrastructure, in particular it must be
    compatible with the various customer premise equipments available
    today.  This means that, in particular, the tunnels must be able to
    traverse one or many NAT boxes of different kinds. There is no
    requirement for any particular NAT traversal technology. However, as
    NAT traversal usually requires an extra layer of encapsulation, the
    tunnel set-up protocol must be able to detect automatically the
    presence of one or more NAT boxes in the path.

I will add text that spells out that when no NAT is present,
simple IPv6/IPv4 encapsulation MUST be used. It seemed obvious to
me, but apparently it will be better to clarify.

	- Alain.

---

From: Fred Templin <[email-masked]>
Date: Thu, 15 Apr 2004 12:04:23 -0700

Alain Durand wrote:

> Note that I'm not advocating for IPv6 NAT here.

I wasn't intending to imply that, but I'm glad to hear you say it.

> I'm saying that

Speaking generally w/o looking at specific scenarios (e.g., 3GPP/2),
I would have to agree. All I'm saying is that explicit NAT traversal
mechanisms should be used only as a last-resort, and unencumbered
IPv6-in-IPv4 tunneling (or, better yet, native IPv6) should be used
instead whenever possible.

Fred
[email-masked]