Re: [v6ops] I-D Action: draft-ietf-v6ops-mobile-device-profile-17.txt - C_REC#9 464XLAT

[Tore Anderson <[e-mail]>]

* Alexandru Petrescu

> What is the name of the software that must exist inside the customer's
> device?

"CLAT". The device located in the provider's network, the "PLAT", is
really nothing but a completely standard Stateful NAT64.

> > In other words, the operator does not need to configure or provision
> > anything beyond Stateful NAT64 + DNS64 for 464XLAT to function.
> 
> But it seems to mandate "464XLAT" to exist inside the customer's
> device, for IPv4-literals, and for non-DNS-based apps.

If you want IPv4 literals to work, you'll need the CLAT, yes. However,
the operator cannot really control this - if you have a device that
supports the IPV6 APN type, but no CLAT/464XLAT support, then you can
connect to the network just fine. You'll have access to IPv4-only
websites etc. through the provider's DNS64/NAT64, but you won't have
access to IPv4 literals.

The only control the network operator has here, is that it can ensure
that all the operator-branded devices it sells in its own store do
support 464XLAT (i.e., by containing a CLAT). If you bring your own
device bought from somewhere else, however, the operator has no way of
knowing if your device contains a CLAT or not.
 
> I also heard that 464XLAT was imported into the cellular world from
> DSL IPv6 deployments.

No, 464XLAT was designed specifically for mobile networks. I've never
heard of any DSL/wireline deployment that uses it (although it is
certainly technically possible).

> I can understand that.  LTE networks bring in high bandwidth; but from
> the networking point of view there is reason to fear regression (no
> more publicly routable IPv4 addresses, no more ping 8.8.8.8, apps must
> use DNS, etc).

I think the need to support IPv4 literals and apps not using DNS
remains with LTE; the actual change is that LTE networks and devices
conform to newer 3GPP releases which include the IPV4V6 APN type.
Thus, devices and networks generally support it. Using IPV4V6, an
operator can provision the handset with both IPv4 and IPv6 addresses,
ensuring that IPv4 literals work - without requiring a CLAT. (As Nick
pointed out, RFC1918/RFC6598 exhaustion might still be an issue for
very large operators though.)

Tore