Subject: RE: [Softwires] IPv4 over IPv6 in Hubs and Spokes?

From: "Durand, Alain" <[email-masked]>
Date: Wed, 18 Jan 2006 09:56:26 -0500

Tim,
 
The point is not do we want IPv4 over IPv6 tunneling or not,
this was already decided: yes, we want it.
 
The issue here is: if we take the existing diagrams describing the v6 over v4 case,
replace v4 by v6 and v6 by v4, do we cover reasonably all the cases or is there something
inherently different in the v4 over v6 case that we absolutely need to introduce another diagram?
 
I'm not sure how even the DSTM scenario you describe is any different from converse of the home PC acting
as a softwire initiator in the v6 over v4 case...
 
If you think otherwise, could you please point out the difference?
 
   - Alain.

________________________________

From: [email-masked] on behalf of Tim Chown
Sent: Tue 1/17/2006 11:12 AM
To: Softwires Mai
ling List
Subject: Re: [Softwires] IPv4 over IPv6 in Hubs and Spokes?

On Fri, Jan 13, 2006 at 09:36:48AM -0500, Durand, Alain wrote:
> 
> Unless somebody can show that there is something more that absolutely need
> to be described for the v4/vg6 case, I would suggest we stick to a minimum number of diagrams
> to keep things simple.

I think there's a case here to be made for the IPv4 in IPv6 scenario, namely
the IPv6 dominent network deployment.

There are a couple of scenarios.

1) IPv4 connectivity over an IPv6 access network:

                      +-------+   +-------------+  +--------+
                      |       |   | Softwire    |  | IPv4   |
   +-----+  +-----+   | IPv6  |---| concentrator|--| Network|=>Internet
   |Host |--| HGW |---|       |   +-------------+  +--------+
   +-----+  +-----+   |Network|
                      +-------+
                   _ _ _ _ _ _ _ _
                  () _ _ _ _ _ _ _()
                   "softwire"
   |--------------||--------------||-------------------------|
      Dual stack      IPv6 only         IPv4 or dual stack
    (Or IPv4 only
        host)

I think this isn't exactly common yet.

2) IPv4 connectivity over an IPv6 site network

This is more 'contentious' because it is a little different to what has
been discussed already.   It's the problem space that DSTM currently
solves and - if people feel DSTM isn't an ideal solution - we should
cater for a better solution with softwires.

So the scenario would be something like this:

                      +-------+   +-------------+  +--------+
                      |       |   | Softwire    |  | IPv4   |
   +-----+            | IPv6  |---| concentrator|--| Network|=>Internet
   |Host |------------|       |   +-------------+  +--------+
   +-----+            |Network|
                      +-------+
           _ _ _ _ _ _ _ _ _ _ _ _
         ()_ _ _ _ _ _ _ _ _ _ _ _()
                   "softwire"
   |-------||---------------------||-------------------------|
     Dual stack      IPv6 only         IPv6 or dual stack
    
In the DSTM case, the concentrator would be the DSTM tunnel server,
with the host running a DSTM client for address acquisition and tunnel
handling for the IPv4 application running to an external IPv4 target,
i.e. the classic use of DSTM for dual-stack hosts on an IPv6-only network
to talk to IPv4-only nodes on the external Internet.

Or has this been discussed and deemed out of scope?

Tim

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---

From: Tim Chown <[email-masked]>
Date: Wed, 18 Jan 2006 15:28:07 +0000

> this was already decided: yes, we want it.

Understood.
  
> inherently different in the v4 over v6 case that we absolutely need to introduce another diagram?

Sorry, I was catching up on a few dozen mails, and was responding to the
call for a 4-in-6 example (because the three used were all 6-in-4).
  
> as a softwire initiator in the v6 over v4 case...

Well, there is not necessarily a HGW device present as there would be in a
home environment.  The 'DSTM scenario' tunnels directly from the host to 
the concentrator.  

If the three figures are kept for the hub section, perhaps reverse the
4/6-ness of example 2 and remove the HGW to indicate we are interested in
a host-based solution in a v6 dominant network (as called for in the
ent-analysis/scenario documents)?

Note I'm not making a case for DSTM, simply that DSTM 'solves' a current
scenario and for interoperability's sake it would be nice if the softwire
solution (which may or may not reuse components that DSTM uses like TSP)
catered for it.

I'm currently open-minded about the mesh scenario, but I do share some of 
Pekka's concerns.

Tim