Re: IPv4 flag day

[Arie Vayner via NANOG <nanog () lists nanog org>]

John,

> NAT overload/IP masquerade/PAT all work with IPv6 too.  So number your
> local LANs in ULA, and do that all you want.  Modulo some address
> selection issues, this works quite well.

> So -- we have parity in IPv4/6 if we can just get an RFC out the door
> that defines how NAT should be done to avoid 20 years of creating
> middleware that takes care of corner cases.

I totally agree! This is the real gap I was alluding to.
I believe that the path of least resistance for IPv6 in Enterprise space is
to make IPv6 "feel the same as IPv4" for the average sysadmin.

Tnx
Arie

On Tue, Jun 16, 2026 at 8:43 PM John Osmon via NANOG <nanog () lists nanog org>
wrote:

> On Tue, Jun 16, 2026 at 06:23:37PM -0700, Matthew Petach via NANOG wrote:
>
> [... lots of "NATv4 is simple, IPv6 is complex" elided...]
>
>
> > For small networks, IPv6 fails to provide any significant benefit beyond
> > what people are already experiencing in IPv4 networks behind NAT devices,
> > and we're collectively trying to gaslight each other and the rest of the
> > world into thinking it does.
>
> By "small networks" you really mean "any network where proxy access to
> the Internet is sufficient."  There's a lot of those.  Some of them are
> rather large.  The devices behind the NAT aren't on the Internet -- the
> NAT is, and it proxies for them.
>
> NAT overload/IP masquerade/PAT all work with IPv6 too.  So number your
> local LANs in ULA, and do that all you want.  Modulo some address
> selection issues, this works quite well.
>
> So -- we have parity in IPv4/6 if we can just get an RFC out the door
> that defines how NAT should be done to avoid 20 years of creating
> middleware that takes care of corner cases.
>
>
> > I sincerely hope to be convinced otherwise.  :/
>
> I won't try to convince you of anything.  I'll agree that you're right.
>
> We gave up trying to give every host a unique address -- proxies were
> sufficient for them to get to the services they really wanted.
>
> However -- we WILL run into a day in the future where the IPv4 address
> space isn't sufficient to number all of the required service/proxy
> endpoints.  So we SHOULD be perfecting the alternatives.
>
>
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