Re: V6 still not supported

The only far ressemblance with 6to4 is the thing that was actually nice in the
design, the automatic word in automatic tunnel. Which for the rest of us mean
s stateless. Compared to CGNATs that is huge.

Any form of communication with the current IPv4 internet requires some
sort of CGNAT. We no longer have enough IPv4 addresses to give each customer
an unique one. So some ISPs are forced to map multiple customers to a
single IPv4 address. Which results in CGNAT. Technically, A+P (address
plus port) mapping is a bit different, but for the customer that doesn't
make a lot of difference. And A+P has serious scalability problems.

Beyond that the proposal is not a tunnel and more akin to a nat64 since it all
ows v6 nodes to talk to v4 nodes. The network can be pure v4 or pure v6 if the
method is implemented as a bump in the stack at the wrong end.

You mostly ignored the routing problems I brought up. With NAT64 each ISP
is in full control over all routing. Your problem has routing aspects
that are not under control of the ISP.

Your response is also missing the capability to extend the IPv4 network a mill
ion times. Or drop it completely while maintaining IPv4 applications.

Extending IPv4 is fine (except for the installed base of IPv6). It is not fine
if the extension leads to problem in other areas, like routing.

There are other problems to consider. For example, IPv6 can be added
transparently to a network with legacy IPv4-only hosts. Hosts can get a
public IPv6 address and a RFC 1918 IPv4 address. I wonder how in your
approach such a mix of legacy and new hosts will work out.

6to4 was meant for early v6 to interconnect islands. A solution for a problem
that never really existed. Solutions without a problem aren?t usually popular.

We seem to have a different recall of history. 6to4 was extremely popular.
Popular enough that major content providers did not turn on IPv6 until
host stacks were modified to essentially kill 6to4. (in case we are talking
about different 6to4 protocols. I meant the one that interconnects with the
non-6to4 IPv6 internet. So more than just islands)

Philip Homburg wrote:

Any form of communication with the current IPv4 internet requires some
sort of CGNAT.

Any form of communication with the current IPv4/IPv6 mixed internet,
except for dual stack, also requires some sort of NAT.

Technically, A+P (address
plus port) mapping is a bit different, but for the customer that doesn't
make a lot of difference.

A+P is equivalent to end to end NAT, though end to end NAT
only needs plain IP routers behind gateways, whereas A+P
requires routers with A+P routing capability for large
(but not very large) number of hosts. As networks behind
the gateways are local and not so large, it can not be a
practical problem.

And A+P has serious scalability problems.

No, not at all.

            Masataka Ohta

Seems that we lost sync.

I would not rephrase so I made it a draft to make it easy to socialize: Yet Another Double address and Translation Technique

The goal is NOT to allow any IPv4 host to talk to any IPv6 host. For that I agree you need the traditional transition mechanisms, CG-NATs etc.

The plan has 2 phases:

- The first phase called YADA extends the reach of IPv4 using a common IPv4 space that is like an elevator shaft.

        / /
       / |------------| realm 1 /
      / /. /. /
     / / . shaft / . (current IPv4 Internet) /
    / |------------| . /
   / . . . . /
               > . | |
        / | . | | /
       / | |---------|--| realm 2 /
      / | /. | /. /
     / |/ . shaft |/ . /
    / |------------| . /
   / . . . . /
               > . | |
               > . | |
               > > .
               > > .
               . . |
               . . |
               > . | |
        / | . | | /
       / | |---------|--| realm N /
      / | / | / /
     / |/ shaft |/ /
    / |------------| /
   / /

There's more in the draft as to how forwarding happens. But only a few routers serving the shaft have to do anything and it's dead simple.

In that phase, we can now have many realms that are parallel to the IPv4 Internet of today. IPv4 acts as normal in each realm.
The phase upgrades IPv4 host to understand an IP in IP format that allows to traverse the shaft. At that time, scale is no more the issue for IPv4.

- The second phase called YATT does a stateless translation between a v4 in v4 and a v6 address. No CG-NAT.


I think this message is 4 days early.


Actually, Owen, now the day has come, I can say I love it.

No one likes tradeoffs. No one wants to compromise.

Ryland just told us we have a near perfect title for a spec that is bound to be hated.

Keep safe;


I had no idea that actually went through. That makes my morning much better knowing someone saw it hahaha. I’m all in on v6.

Thank you,
– Ryland