Subject: RE: (ngtrans) draft-wiljakka-3gpp-ipv6-transition-00.txt

From: "Karim El-Malki (EAB)" <[email-masked]>
Date: Fri, 19 Jul 2002 04:23:48 +0200

Hi Luc,

IMS only allows IPv6 connectivity (PDP Contexts).
It's not possible to activate an IMS IPv4 PDP Context,
therefore we need translation for the case where an
IMS (SIP-based) IPv6 host communicates with an IPv4 host.

/Karim

-----Original Message-----
From: BELOEIL Luc FTRD/DMI/CAE
To: [email-masked]; [email-masked]; [email-masked]
Cc: [email-masked]; MARTIQUET Nicolas FTRD/DMR/ISS
Sent: 2002-07-19 01:58
Subject: RE: (ngtrans) draft-wiljakka-3gpp-ipv6-transition-00.txt

Hi all, 

I'm happy to see a draft that proposes the use of native connection each
time needed.

Moreover I totally agree that UE must be dual-stack (in first phases)
and that IPv4 connectivity (IPv4 PDP context) should not be always-on.

But, I do not feel at ease with section 4.1 (dual-stack UE) in addition
with section 5.2. (UE connecting to a node in an IPv4 network through
IMS). I see a case which seems not to be addressed in the draft.

Consider a dual-stack UE with IPv6-only connectivity (because of IPv4
addresses scarcity) that initiates a communication through IMS (with
SIP) towards another node named C. Consider C is IPv4-only and outside
the operator network. Don't you think that an IPv4 PDP context should be
initiated (by UE or network) so as to allow a native end-to-end
connection ?

Could you help me ?

Luc

-----Message d'origine-----
De : [email-masked] [mailto:[email-masked]]
Envoyé : mercredi 17 juillet 2002 07:13
À : [email-masked]; [email-masked]
Cc : [email-masked]
Objet : RE: (ngtrans) draft-wiljakka-3gpp-ipv6-transition-00.txt

Hi all!

I also think that the issue is in wording and we are happy to clarify
that in the next revision. :-)

We are no way prefering NAT over tunneling. Just because tunneling
remains the end-to-end nature of the communication. However, translation
may be needed in some cases, like in IMS scenario 1.

And about tunneling: what I meant was that if you consider GPRS scenario
2 (or actually scenario 1, where the UE has dual stack capability), I
prefer doing "IPv6 in IPv4" tunneling in the network (the encapsulating
node could be e.g. GGSN or edge router), not in the UE. If you make
tunneling in the network, you can just activate IPv6 PDP context.

What Karim commented about the case that if a dual stack UE is
connecting to a network in which the GGSN does not support IPv6, it is a
relevant thing to make "IPv6 in IPv4" tunneling in the UE and just
activate IPv4 PDP context. That scenario is also very shortly documented
in GPRS scenario 1. 

Best Regards,
		-Juha W.-

-----Original Message-----
From: ext Erik Nordmark [mailto:[email-masked]]
Sent: 17 July, 2002 12:32
To: Karim El-Malki (EAB)
Cc: 'Erik Nordmark '; [email-masked] '
Subject: RE: (ngtrans) draft-wiljakka-3gpp-ipv6-transition-00.txt

> Maybe we need to look at the doc again to clarify this
> but we do have cases where tunnelling from the UE is preferred
> e.g. accessing IPv6-only services (i.e. IMS) when you're roaming
> into a network which only supports IPv4 connections (PDP Contexts).
> There are also cases where translation looks like the way to go
> e.g. Communicating with an IPv4 node when using an IPv6-only
> service (IMS) which mandates IPv6-only connections.
> The recommendations probably need clarifying if they give
> that impression, but regarding the tunnelling I think it was
> meant to prefer the native connection (without tunnelling or
> translation) rather than always recommending against tunnelling
> and for translation.

Thanks. In that case I think the issue is with the wording in the
document.

  Erik

---

From: Brian E Carpenter <[email-masked]>
Date: Fri, 19 Jul 2002 09:47:39 +0200

And how will this work for apps with no ALG available?

   Brian

---

From: Pekka Savola <[email-masked]>
Date: Fri, 19 Jul 2002 14:41:00 +0300 (EEST)

> IMS (SIP-based) IPv6 host communicates with an IPv4 host.

Why does a **SIP-based** IPv6 host need to communicate with an IPv4 host?

You'll just open a huge can of worms wrt. NAT, etc.

Wouldn't it be much simpler to either:
 1) just add a SIP-only ALG, or
 2) (preferably) require that SIP terminals IMS talks with support IPv6?

Some people have also expressed the interest to enable being able to call 
from IPv4-only SIP phones to IPv6 3GPP equipment.  Is this _really_ a 
problem we want to spend much time on solving?  I think the solution 
should be blindingly obvious here.

-- 
Pekka Savola                 "Tell me of difficulties surmounted,
Netcore Oy                   not those you stumble over and fall"
Systems. Networks. Security.  -- Robert Jordan: A Crown of Swords