RE: 3gpp transition solutions, revision -02

[<Jonne.Soininen@nokia.com>]

Hi Luc,

> -----Original Message-----
> Here is my last point, 
> 
> IMS is IPv6-only ok, but IMS is a set of SIP servers.
> SIP is a control protocol that can initiate IPv4-based or 
> IPv6-based flows.
> But 3GPP specs have constrainted nodes, that use IMS SIP 
> server services, only to use IPv6 (signalling + communication 
> flows). The communications initiated by IMS (SIP) are not 
> intend to go through IMS (routing is different).
> 

IMS is not only the SIP server, etc. It comprises the whole system. That is why the media stream between the nodes is actually part of IMS as well.

> So, consider I'm using IMS services, even if:
> - I have a dual-stack node,
> - I have sufficient IPv4 public addresses (some areas are 
> still not constrainted)
> - I may just need private IPv4 address (its depends of your 
> architectures)
> - SIP protocol is efficient enough to allow you to open IPv4 
> and/or IPv6 communications,
> I can not use IPv4.
> 
> So why not using DSTM + ROHC ?

Because then you would be using IPv4 as well, and you would have to have IPv4 on your terminal. 

> Just a comment:
> A transition mechanism (whatever it is) would be necessary 
> until I wanna offer services towards other IPv4-only SIP-based system.

Yes.

> Moreover, I think that dual-stack phones are usefull to use 
> IPv4-only services not based on IMS, and those services may 
> not be disregarded. 

That is why we have the different scenarios (this is under the general scenarios). IMS is IPv6 only, but if you want to have, for example, a connection to your intranet that is IPv4 you can. However, the intranet is not part of the IMS.

Cheers,

Jonne.

> > De : Jonne.Soininen@nokia.com [mailto:Jonne.Soininen@nokia.com]
> > 
> > Hi,
> > 
> > sorry to step into the discussion so late. (I had computer 
> > trouble for a while!)
> > 
> > I would like to remind everybody that as IMS is _exclusively_ 
> > IPv6, and the NAT-PT (or a flavor of that) is just an 
> > interworking solution to a non-IMS network that supports IMS 
> > like services. (Confusing enough?;)
> > 
> > This means that IMS itself has no interworking problems, no 
> > NATs, no NAT-PTs, and no IPv4 - it is only IPv6. Thus, there 
> > are no problems inside the IMS. The NAT-PT would come to the 
> > picture if, for instance, you have to place a call to another 
> > "system" that does not support v6. (It may be that you have 
> > to do another kind of translation as well, e.g. SIP to H.323, 
> > or SIP to ISUP, or whatever.) The NAT-PT would be an 
> > interworking function to an outside world - not an internal part!
> > 
> > People seem to write all the time that with dual-stack you 
> > can fix the interworking problems of IMS. That however is not 
> > true, because you end up with normal NAT for your IPv4 
> > connections. You cannot get (at least in certain areas of the 
> > world) enough IPv4 addresses to even support it as an 
> > interworking method and to have global addresses. 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.
> > 
> > Anyways, the 3GPP specifications (as Hesham pointed out) now 
> > say that this network/system, the IMS, is exclusively IPv6. 
> > We cannot change the specs, and there is no reason for 
> > changing them - the contrary. I would propose that we 
> > concentrate now on solving the problem instead of changing 
> > the problem.
> > 
> > Cheers,
> > 
> > Jonne.
> > 
> > 
> > 
> > > -----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.
> > > 
> > > 
> > 
>