Subject: Re: (ngtrans) RE:

From: Francis Dupont <[email-masked]>
Date: Thu, 14 Sep 2000 19:16:14 +0200

In your previous mail you wrote:

   If there is HTML again then please don't shoot me !

=> there is... Should try a BSD (:-)!
   
   Ok here is exactly what I'm asking about. How do they get routed
   through the HA ?

=> the TEP knows the MN IPv6 address then follows the common rules
for sending a packet to a IPv6 destination (lookup binding cache,
looup destination cache, ...). There is nothing special but the
TEP is likely to be detected/known as a correspondent then routing
is likely to be optimized (ie. the binding cache lookup will succeed).

   Does the Border router or TEP know that this IPv4
   address should be routed to subnet X where the MN's HA is ? 

=> Ah! You should reread the DSTM draft. The TEP encapsulates
IPv4 traffic to the MN into IPv6. The communication between the MN and
the TEP is done by a IPv4 over IPv6 tunnel.

   Because the DSTM draft does not really say how the IPv6-IPv4
   mapping should be done.

=> there is no mapping nor translation. All nodes have a global IPv6
address (at least). A global IPv4 address and a TEP is allocated to
an IPv6 node which needs to communicate with an IPv4 only node.
There is *no* relationship between addresses, the IPv4 address
is just pick up from a pool (this pool can (and will) be smaller
than the number of nodes then scenario 2 has a DOS attack).

   If it only maps it to the COA of the IPv6 node which is what will
   be seen in outgoing packets then it is not very reliable.

=> the IPv4 layer has no knowledge of mobility. The TEP uses the
Home Address of the MN. The COA is only in the binding cache and
is optional (known -> optimized, unknown -> not optimized, ie.
triangular routing via the HA).
I said to George his idea is trivial, should I have said it is too simple (:-)?

   Also in the scenario I mentioned earlier you would
   have to force the IPv6 MN in the foreign domain to reverse tunnel
   through the "home" TEP so that the home TEP would know the mapping.
    
=> no reverse tunnel...

   There is very little in the draft about that.

=> there is very little because there is nothing to explain.

   So that's why I think there are some open issues here

=> there is no issue, only freedom.

   and they depend on two things:
   
   - How does the IPv6 MN acquire the address in a foreign domain
   (Home AIIH vs Foreign AIIH)
   
=> it MAY use a home AIIH or it MAY use a foreign AIIH. The second
one is easier because the proposed tool is DHCPv6 which is a local tool.
The second is a bit harder because current DHCPv6 doesn't work but
you can imagine another way to do it (use AAA for instance).

   - How does the TEP maps the IPv4 and IPv6 addresses.

=> I don't understand your question. The word "map" has too many meanings.

   This has to be done in a reliable way. I don't think it should be
   "guessed" based on the source address in the IPv6 packet.

=> if your problem is the tunnel parameters at the TEP side then there are
two main ways to do it:
 - the TEP is configured by the AIIH server (this is needed in some cases)
 - the TEP gets the addresses from incoming packets from the tunnel (cheap
   because the TEP has to decapsulated them but there is a security issue
   if this is done blindly. I have to add something in the current draft).
The second case is the standard one for scenario 1 with an external
destination (internal destination is special: the TEP is the destination).

Regards

[email-masked]

---

From: "Hesham Soliman (EPA)" <[email-masked]>
Date: Fri, 15 Sep 2000 02:37:46 +1100

If there is HTML again then please don't shoot me !
I'm working on it, I'm using a certain product that
works sometimes !!! No naming :)

   Ok, let me explain properly what I meant. My question
   is: If an IPv6 MN is in a foreign domain. can it request
   an IPv4 address from it's home domain ? ie. Home AIIH ?

=> it can do what it wants. I think there are three policies:
 - local (ie. foreign domain). Simple but perhaps too simple.
 - home (ie. home domain/AIIH). Not hard, this can be a good
   or a bad choice...
 - close to the peer. Harder but the best if there is only one peer.
   (of course the knowledge of what/where the peer is is needed).

Yes I agree with all that. But my question is below:

   If the answer is yes, then how do IPv4 packets addressed to
   that IPv4 address get routed to the IPv6 MN's subnet in the 
   foreign domain ?

=> they are routed according to IPv4 routing to the TEP, then
they are IPv6 routed to the MN through the HA (if not optimized) 

Ok here is exactly what I'm asking about. How do they get routed
through the HA ? Does the Border router or TEP know that this IPv4
address should be routed to subnet X where the MN's HA is ? 
Because the DSTM draft does not really say how the IPv6-IPv4
mapping should be done. If it only maps it to the COA of the IPv6
node which is what will be seen in outgoing packets then it is not
very reliable. Also in the scenario I mentioned earlier you would
have to force the IPv6 MN in the foreign domain to reverse tunnel
through the "home" TEP so that the home TEP would know the mapping.
 
There is very little in the draft about that. So that's why I think 
there are some open issues here and they depend on two things:

- How does the TEP maps the IPv4 and IPv6 addresses. This has
to be done in a reliable way. I don't think it should be "guessed"
based on the source address in the IPv6 packet.