Subject: Re: DSTM Considered Harmful [Re: (ngtrans) final ngtransagendaforIETF-53 in Minneapolis]

From: "Christian Huitema" <[email-masked]>
Date: Tue, 19 Mar 2002 15:11:34 -0800

> How will work, for example, a web browser with an IPv4 address in the
URL
> if you use BIS/BIA ?

The BIA would rewrite "connect AF_INET 1.2.3.4" to "connect AF_INET6
x:x:x::1.2.3.4", where x:x:x::/n is either the IPv4 mapped address
prefix (configuration less environment) or a prefix managed by a
specific NAT-PT (explicit configuration). The packets would be routed to
the NAT-PT, which would then do its stuff.

> >We may try to provide access to legacy
> >applications using a dual-stack mechanism,
> 
> then you need an IPv4 address per host and manage IPv4 routing.

Well, there are two types of dual stack mechanism: an actual dual-stack
with, for example, two types of packets running over Ethernet, and a
DSTM like mechanism, in which the IPv4 packets are sent over IPv4. In
practice, I tend to believe that you need an IPv4 address per host in
both cases. As I wrote previously, I really don't believe in time
sharing, which implies that we should be ready to give a different IPv4
address to every node, even if we use 4over6.
 
Comparing multiplex over Ethernet or using 4over6 is not a black and
white thing. 4over6 let you save the management of IPv4 in subnets and
routers, but it introduces new components (servers and tunnels), and the
transmission of IPv4 packets between two local hosts is sub-optimal;
also, if you want to support old IPv4 only hosts, you will have to give
them some "real IPv4" infrastructure. It would be very nice to have a
clear picture of the target environment before we do the evaluation.

By the way, the "port range" option is probably not compatible with any
attempt to perform local communication. Think of two 4over6 nodes that
would happen to get the same address and different ports, and then try
to communicate. The results will be interesting. So, deciding whether
"local communication between legacy IPv4 applications" belongs to the
scenario or not is really an important issue.

-- Christian Huitema

---

From: Pekka Savola <[email-masked]>
Date: Wed, 20 Mar 2002 01:32:08 +0200 (EET)

> the NAT-PT, which would then do its stuff.

Actually not (AFAIR): I brought this up in BIA last call and the response
was basically "we'll see what happens, it's experimental"; it works, as
specified, only if there is a DNS query, ie. not dotted-quad (or some
weirder) formats.

(Basically) what you're describing would be supported via extending
function & address mapper specification a bit.

I think you're mixing up BIA with NAT-PT and such though: with BIA, you 
basically don't need any NAT-PT or such.

-- 
Pekka Savola                 "Tell me of difficulties surmounted,
Netcore Oy                   not those you stumble over and fall"
Systems. Networks. Security.  -- Robert Jordan: A Crown of Swords

---

From: Brian E Carpenter <[email-masked]>
Date: Wed, 20 Mar 2002 01:34:15 +0100

Pekka Savola wrote:
...
> basically don't need any NAT-PT or such.

Indeed. The whole point of BIA is to avoid the need for a NAT-PT box;
both protocol translation and address translation take place in the
shim on the socket API.

   Brian

---

From: Myung-Ki Shin <[email-masked]>
Date: Wed, 20 Mar 2002 11:18:10 +0900

Christian Huitema wrote:

> ....

  First, I'd like to classify the problem space on transition.

   1- An IPv6 node in an IPv6 network (no IPv4 routing) wants to talk to
       an IPv4 node in legacy IPv4 Internet, (and vice versa).
   2- A legacy IPv4 application on IPv6 node (dual stack) wants to
       talk to other IPv6 destinations (and vice versa).

   Problem 1 is about connectivity (tunneling or translation),  the
solutions
   would be NAT-PT, DSTM, etc.
   Problem 2 is about application transition - the solution would be
   BIA.

   Now, there will be a situation on combination of problem 1 & 2.
   (that is, when an IPv6 node wants to talk to another IPv6 destination
   (with IPv6 native or tranlslated/mapped address) and  there is no
application
   to do so ....).
   So, we (network/node administrators) will need NAT-PT+BIA or DSTM+BIA,
etc.

   I think the "local communication between legacy IPv4 applications
   under DSTM-port option"  problem is inherent from problem 2.
   So, we can avoid the possibility by using BIA.
   For local comunication, IPv6 will be used.
   If we achieve this, DNS query results might be very important.

   Myung-Ki.

---

From: "GwangHoon Kwark" <[email-masked]>
Date: Wed, 20 Mar 2002 13:46:42 +0900

Let me introduce myself. I'm the head of R&D center in i2soft which is a co-develope company regarding transition mechanism implementation with ETRI in which Mr. Myung-Ki Shin and at. al  are engaged.

I agree with Shin. The BIA and DSTM can be co-existested for IPv4/IPv6 Coexistence within Dual stack Host  with different functionality. Each mechanism has its own mission. 

  An IPv4 appl on Dual Stack Host in IPv6 Net. <-> An IPv6 appl on Host in IPv6 Net.
      :  BIA can be used 

  An IPv4 appl on Dual Stack Host in IPv6 Net. <-> An IPv4 appl on Host in IPv4 Net.
      :  DSTM can be used

  An IPv4/IPv6 appl on Dual stack Host in IPv6 Net. <-> An IPv4 appl on Host in IPv4 Net.
      :  DSTM can be used

  An IPv4/IPv6 appl on Dual stack Host in IPv6 Net. <-> An IPv6 appl on Host in IPv6 Net.
      :  Native connnection can be used

The above mechanism gets more meaning if they are co-existed within a same host. For the exact selection, the result for DNS query is very important. 

The above mechanism is the core of our CHADH Framework which is presented by me in IPv6 International Summit, Seoul, Korea, Jul., 2001.   
Its main implementation has just finished in Windows 2000 and tested successfully currently. And has no problem regarding coexistence.

In terms of DSTM, we considered deeply on IPv4 address release mechanism to DSTM server for high IPv4 address utilization.

Gwang-Hoon Kwark

> -----Original Message-----
> From: [email-masked] [mailto:owner-
> [email-masked]]On Behalf Of Myung-Ki Shin
> Sent: Wednesday, March 20, 2002 11:18 AM
> To: Christian Huitema
> Cc: [email-masked]; Bound, Jim; Octavio Medina; Tim
> Chown; NGtrans List
> Subject: Re: DSTM Considered Harmful [Re: (ngtrans) final
> ngtransagendaforIETF-53 in Minneapolis]
> 
> 
> Christian Huitema wrote:
>