RE: 3gpp transition solutions, revision -02

[<Jonne.Soininen@nokia.com>]

Hi Brian,
> (BC) And if that is the case, the IWU that does this 
> translation can be dual
> stacked, with its IPv6 stack talking to IMS and its IPv4 stack talking
> to the legacy system. If you do that, NAT-PT isn't needed.

OK, for the SIP signalling part you have to use an IWU (or a NAT-PT with a SIP ALG, which I guess would be the same thing, right?). As Jasminko pointed out there is also the "media stream" (SIP only negotiates the session e.g. VoIP - the data goes end-to-end). There NAT-PT (or a mutation of that) could be used.

> > In addition, you end up having a dual-stack in your phones 
> until the end of time or to the point where the last 
> _possible_ IPv4 device in the world would be extinct! These 
> are just some of the reasons why 3GPP decided to have IPv6 only IMS.
> 
> (BC) Which was an excellent decision.

I think so too!

> 
> Now, what's the answer to Keith's point below? 
> 

If I got it right, the question was if NAT-PT is sufficient. No, you need application level gateways in many cases (like in your IWU). But this is "business as usual" in NATed environments. Though, I hope the NAT-PT for the media stream can be pretty basic.

Cheers,

Jonne.

>   Brian
> 
> > 
> > > -----Original Message-----
> > > From: ext Keith Moore [mailto:moore@cs.utk.edu]
> > > Sent: Thursday, November 07, 2002 9:21 AM
> > > To: BELOEIL Luc FTRD/DMI/CAE
> > > Cc: Brian E Carpenter; Hesham Soliman (EAB); v6ops@ops.ietf.org
> > > Subject: Re: 3gpp transition solutions, revision -02
> > >
> > >
> > > > For SIP-based services an application proxy is not sufficient.
> > >
> > > and NAT-PT is sufficient?  from my limited knowledge of SIP I
> > > find this
> > > surprising.
> > >
> > > however I don't see a huge problem with using NAT-PT only for
> > > a specific
> > > set of well-defined services on networks with known 
> characteristics;
> > > presumably it can be adapted as needed to accomodate 
> those services.
> > >
> > > the imposition of NAT-PT on other services is of course a
> > > separate question.
> > >
> > >
> 
> -- 
> - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
> Brian E Carpenter 
> Distinguished Engineer, Internet Standards & Technology, IBM 
> On assignment at the IBM Zurich Laboratory, Switzerland
> 
>