RE: 3gpp-analysis: Recommendation on tunneling in the UE

["Karim El-Malki (HF/EAB)" <karim.el-malki@ericsson.com>]

 > Consider rewording:
 > =====
 >     However, the UE may attach to a 3GPP network, in which 
 > the Serving
 >     GPRS Support Node (SGSN), the GGSN, and the Home 
 > Location Register
 >     (HLR) support IPv4 PDP contexts, but do not support IPv6 PDP
 >     contexts. This may happen in early phases of IPv6 deployment.
 > 
 >     In theory, the user's own 3GPP operator might not 
 > support IPv6 at 
 >     all.  However, such scenario is considered out of scope of this 
 >     document; the considerations for Unmanaged networks would apply
 >     [UNMANSCEN] [UNMANAN].

There are some differences between unmanaged and 3gpp. For example the
"gateway" (when it runs NAT) in Unmanaged scenarios puts some restrictions
on the mechanisms that can be used. The same case does not apply to a
3gpp UE (which is not going to run NAT). So cases which Unmanaged considers
of limited applicability are instead applicable here (e.g. single private
v4 host connected to v6 ISP over a v4-only gateway/connection). IMO we should
qualify the above statement further by saying that the 3gpp scenarios involve
single priv. v4 host + ipv4 gateway cases, therefore some of the solutions
which are recommended in Unmanaged are not equally recommended here. However
on the other hand that seems to be a reason for considering them in the 3gpp
analysis doc in the first place...

 > 
 >     Presupposing some form of IPv6 support, there are two cases
 >     to consider when the visited network does not support IPv6 PDP 
 >     contexts:
 > 
 >        1. The UE is used as a "modem" with e.g. a laptop computer.
 >           The UE does not have to even support IPv6 PDP contexts,
 >           and all the transition issues are dealt with by the
 >           supporting equipment.
 > 
 >        2. The UE is used independently, running IPv6 applications,
 >           and would desire IPv6 connectivity.
 > 
 >     In both cases, it may be desirable to be able to create a tunnel
 >     between the UE (or the supporting equipment) and the user's 3GPP
 >     operator's IPv6 equipment.
 > 
 >     A way to easily manage the setup of a simple configured tunnel 
 >     would be sufficient, unless the basic IPv6 deployment in visited
 >     networks could be assumed and no tunneling would be 
 > needed at all.
 
I don't think it is feasible to assume that we can easily set up
configured tunnels in UEs without any user intervention. It would
certainly need some automated mechanism which is probably what you mean
by "easily manage the setup". Without having to specify a new one there
are existing mechanisms for this that can make things easier and more
transparent to users. I think it makes sense to refer to ISATAP as an
existing solution that addresses this problem. I would suggest to add
to the end of the parag above:

   A 3GPP operator that provides individual hosts with private IPv4
   addresses could install an ISATAP router for example, so that each
   of these hosts could obtain a globally routable IPv6 address.

/Karim