Subject: [BEHAVE] some comments about draft-baker-behave-v4v6-translation-00

From: marcelo bagnulo braun <[email-masked]>
Date: Mon, 03 Nov 2008 11:29:28 +0100

Hi,

I have a few comments about draft-baker-behave-v4v6-translation-00

regards, marcelo

section 1. Introduction and Motivation

   o  No systems in the IPv6 domain use IPv4-mapped addresses, which is
      a lot like IPv4 NAT behavior and prevents all IPv4 systems from
      accessing servers in the IPv6 domain, or

that's not strictly true, right? I mean, you can create static mappings 
for some ports, like what it is done for nat44 nats and that would allow 
you to have some servers listiening in some ports, even if there are no 
IPv6 addresses using the IPv4-mapped format i guess.

   o  If H2 decides to connect to S1, it asks the DNS server for a AAAA
      record, and sends its datagram to the IPv6 address in the
      response.  Unknown to it, routing takes it to a translator, which
      emits an IPv4 datagram into the IPv4 domain.

suggest to remove the "unknown to it".

   o  If H1 seeks S1, is obviously gets S1's IPv4 address and
      communicates with it directly; in the same way, if H2 seeks S2, it
      gets the AAAA record and communicates directly with S2 even if the
      address it chooses happens to be a mapped IPv4 address.

Is hairpinning supported? (behave requirements says it MUST be supported 
for nat44, but i don't know if it would apply for this type of translators)

later on:

   A stateful mapping of this kind requires appropriate handling of port
   numbers and checksums, and of creation and deletion of state, as
   described in [  Internet-Draft IPv4/IPv6 Translation October 2008 
Network Address and Protocol 
   Translation from IPv6 Clients to IPv4 
Servers"'>I-D.bagnulo-behave-nat64].

there seems to be something wrong with the format here...

later on:

   o  If H4 decides to connect to S1 or S2, it asks the DNS server for a
      AAAA record, and sends its datagram to the IPv6 address in the
      response.  Unknown to it, routing takes it to a translator, which
      emits an IPv4 datagram into the IPv4 domain.  If the prefixes used
      by the translators are the same, the choice of translator is
      immaterial; if they are different, routing will take it to the
      right translator.

suggest to remove the unknown to it.
Second, i don't think the choice is inmaterial, actually it is a routing 
choice, which will take the packet to the shortest nat and will achieve 
load balancing features. I guess that the case of routing fluctuations 
where the packets of the same flow may end up in different nats should 
be considered, but maybe it is considered later on

1.3. Stateless vs Stateful Mode

   In the stateful mode, the system with the IPv4 address will be
   represented by that same address type, but the IPv6 system may use
   any [RFC4291] address except one in that range.  In this case, a
   translation table is required.

and in addition, the IPv6 nodes will chare the IPv4 addresses, 
multiplexing it either in time or using the port

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From: "Dan Wing" <[email-masked]>
Date: Mon, 3 Nov 2008 07:49:15 -0800

> Is hairpinning supported? (behave requirements says it MUST 
> be supported for nat44, but i don't know if it would apply for 
> this type of translators)

(posting as an individual)

Yes, but that would only be necessary for address referrals.

More typical, non-referred traffic between hosts in the IPv6 
domain (H2 and S2) does not go through the translator.  The IPv4
case goes without saying, but is analogous to the IPv6 case:
traffic between hosts in the IPv4 domain (H1 and S1) does not
go through the translator.  For IPv6-to-IPv6 communication
(H2 to S2) the translator is not used, even if H2 or S2 (or
both) happen to use their "mapped IPv6" address, the translator 
is still not used.  The IPv6 mapped address block does not 
have the same IPv6 prefix as the translator.

-d

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From: Xing Li <[email-masked]>
Date: Tue, 04 Nov 2008 14:04:04 +0800

> have the same IPv6 prefix as the translator.
Exactly. xing