Subject: RE: draft-ietf-ipngwg-addr-select-01 comments

From: Brian Zill <[email-masked]>
Date: Fri, 8 Sep 2000 20:46:05 -0700

> > Page 6, Section 3
> > 
> >    Should an additional restriction like the following be
> >    added to the candidate set of source addresses?
> > 
> >     "For IPv4 Mapped destination addresses, the set of
> >      candidate source addresses must only include IPv4 Mapped
> >      addresses. For any other destination address, the set
> >      of candidate source addresses MUST NOT include IPv4
> >      Mapped addresses."
> 
> Yes.

No :-)

In the first quoted sentence, the set of candidate source addresses must
also include IPv4 *Translated* addresses, or nodes in a SIIT cloud won't
work.  And on the other end, translators need to be able to send from IPv4
Mapped addresses to IPv4 Translated addresses.

So how about:

      "For IPv4 Mapped destination addresses, the set of
       candidate source addresses must only include IPv4
       Mapped and IPv4 Translated addresses.  For any other
       destination address, the set of candidate source
       addresses MUST NOT include IPv4 Mapped addresses."

Note I didn't change this to regulate the use of IPv4 translated addresses
as destination addresses, since a node inside a SIIT cloud should be able to
talk to other local nodes using its translated address even if the other
node has a regular (i.e. non-translated IPv4) IPv6 address.  Or at least I
believe it should.  However, I think allowing this means that for source
address selection purposes, IPv4 translated addresses should get less
preference than global addresses - they're essentially a weird kind of
site-local addresses.

But if you wanted to restrict the use of translated addresses just to
communication with the translator, you could say something like:

      "For an IPv4 Mapped or IPv4 Translated destination
       address, the set of candidate source addresses must
       only include IPv4 Mapped and IPv4 Translated addresses.
       For any other destination address, the set of candidate
       source addresses MUST NOT include IPv4 Mapped addresses
       or IPv4 Translated addresses."

But my vote's for my first one.

--Brian
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