Subject: Re: terminology proposal: NAT+PT (or NAT64 ?)

From: Pekka Savola <[email-masked]>
Date: Thu, 15 Nov 2007 19:29:40 +0200 (EET)

On Thu, 15 Nov 2007, Rémi Després wrote:
> > unicast RPF just allows advertised prefixes, and I suspect in the
> > model you have in mind, the mapped addresses would not be advertised
> > in routing.
> The full mapped addresses would of course not be routed (128 bits long).
> But their 0/64 prefix would be.

Do you have a more specific idea how this would work?

How do you prevent folks who advertise ::/64 from sending 
packets from someone else's source address?

-- 
Pekka Savola                 "You each name yourselves king, yet the
Netcore Oy                    kingdom bleeds."
Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings

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From: Keith Moore <[email-masked]>
Date: Thu, 15 Nov 2007 17:47:50 -0500

RÃ©mi DesprÃ©s wrote:
> Keith Moore wrote :
> > one use case for v4 NATs is mapping between two networks using the
> same range of RFC 1918 addresses.  in those cases addresses get
> substituted in both directions.
>
> Substitution of both addresses seems strange to me, at least in the
> context of IETF, but I am interested in learning aboiut it.
> Would you have a reference where this usage is documented?
I've never seen anything published about it, I've only heard of it
actually being used.  Of course, it's not "in the context of IETF" as
the people who use such setups are interested in solving their immediate
problems rather than in what makes sense for the whole Internet.
> In any case, this is different from the NAT-64 case.
I don't know what you mean by NAT-64, but be assured that translations
between v4 and v6 necessarily involve address substitution in both
directions.
> The IPv6 prefix to be used, when an IPv4 source address has to be
> converted into an IPv6 address, is the mapped addres prefix ::FFFF/36.
that's simply not acceptable.

Keith