On 26/nov/2013, at 10:31, Lorenzo Colitti <[email protected]> wrote:

> On Tue, Nov 26, 2013 at 5:55 PM, Doug Barton <[email protected]> wrote:
> Which uses more IPv4 addresses, a traditional IPv4 NAT or 464xlat? At the end 
> of the day the PLAT still has to talk to the v4 net.
> 
> Oh, I forgot - the answer to that question is that the traditional IPv4 NAT 
> uses much more IPv4 space. This is because the traditional IPv4 NAT needs 
> private IP addresses to number the endpoints.
> 
> If you have fewer than 10M subscribers this might not matter, but if you're, 
> say, a mobile operator with 50M subscribers, you either number endpoints 
> using RIR space, or you number them with bogon space, or you have to use 
> overlapping RFC1918 realms. RIR space is about to run out. Bogon space is 
> risky, and overlapping RFC1918 is painful for operations and causes 
> application breakage.

Well, I understand that there is value in moving towards an IPv6-only backbone, 
but, even in that case, I find it safer to provide IPv4 via DS-Lite rather than 
via 464xLAT. In my view, translating between different IP versions can only 
produce more problems.

-- 
Marco Sommani
Consiglio Nazionale delle Ricerche
Istituto di Informatica e Telematica
Via Giuseppe Moruzzi 1
56124 Pisa - Italia
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