Re: [v6ops] Status of CLAT implementation on iPhone? (IPv4 apps on IPv6-only PDP type)

Tore Anderson <> Mon, 23 February 2015 18:09 UTC

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Date: Mon, 23 Feb 2015 19:09:28 +0100
From: Tore Anderson <>
To: Ca By <>
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Subject: Re: [v6ops] Status of CLAT implementation on iPhone? (IPv4 apps on IPv6-only PDP type)
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* Ca By

> On Mon, Feb 23, 2015 at 7:16 AM, Alexandru Petrescu <
>> wrote:
> > Le 23/02/2015 15:11, Lorenzo Colitti a écrit :
> >
> >> They are also free to reuse existing implementations of clat, such as
> >>  the one that Android uses, which is BSD-licensed.
> >
> > Maybe end users will install it and it will work off-the-shelf, just
> > like every other app.
> This is not a path towards success since it requires the user to care
> about how their connectivity is achieved.

Assuming it's possible to write such an app for iOs in the first place,
couldn't you pre-load it on the handsets you sell and have it start up
automatically? If so, the user wouldn't be required to care. As I
understand it, it's common carrier practise to pre-load the handsets
with other kinds of "value add" apps anyway, right?

For example: Orange Poland's 464XLAT deployment. As I understand it,
they are *not* using DNS64, so I guess that necessarily means they
pre-configure the handsets' CLAT with their NAT64/PLAT prefix before
shipping them the customers. So if doing such custom modifications is
doable, pre-loading a CLAT app doesn't seem impossible either.

It wouldn't work for for retail handsets of course, but I understand
that in the US the majority of people buy their handsets from their
carriers rather than from retail stores anyway, so perhaps it's okay
that those relatively few customers that bring retail iPhones onto your
network either 1) get IPv4-only for now, or 2) will be asked to install
the (presumably free) CLAT app if they want Skype to work.

> It would substantially and immediately improve my IPv6 deployment, and
> restoration of a proper e2e IPv6 internet,  if Apple would release CLAT as
> part of their OS.

For the record, I'm not disagreeing that having it in iOS proper would
be the optimal solution. It just seems to me there's another viable way
forward that does not depend on Apple being the ones to implement the
CLAT. But I'm probably missing something?