3gpp-analysis: IMS/SIP transition [RE: NAT-PT Applicabilty for 3GPP]

[Pekka Savola <pekkas@netcore.fi>]

Hi,

I hijacked the thread to bring up a point about IMS/SIP transition in the 
3GPP analysis document as it is now..

On Fri, 14 Nov 2003, Suresh Satapati wrote:
> This whole "subset applicability" argument stems from incorrect
> assumption that NAT-PT (RFC 2766) mandates DNS-ALG.

Maybe, maybe not..

> In the past for v4 land, ALGs have been specified in separate documents.
> For e.g. RFC 2663/3022 clearly defines the role of "NAT", and for
> DNS-ALG there is RFC 2694.

Yes, but then again, you don't need DNS-ALG in the v4<->v4 NAT, because
the destination address families are the same.  On the other hand, you
*do* need it in NAT-PT (or, you have to get the corresponding
functionality in some other way, e.g. manual configuration).

But that aside...

The critical point, I think, is whether the 3GPP analysis about IMS
interworking is written so that it recommends NAT-PT.  Personally, I don't
think we should do that.  

Instead, we should defer the problem to a SIP working group (SIPPING?) to
figure out.. because *they* will be using SIP for interaction, and they
know best which kind of solution they'd need (whether based on NAT-PT or
something else).  I don't think v6ops has the expertise to specify which
method would be most appropriate in this SIP/IMS internetworking scenario.

-- 
Pekka Savola                 "You each name yourselves king, yet the
Netcore Oy                    kingdom bleeds."
Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings