[ipv6-wg] IPv6 only network at RIPE 68

* Philip Homburg

> Note, I'm talking about the proposal to make the detault meeting 
> network support 464XLAT. I don't think there is any proposal to make
> the default meeting network IPv6-only (i.e. without any support for
> IPv4)

I don't think you can say that "the network support supports 464XLAT"
as 464XLAT consists of two components, of which only one (the PLAT, or
in other words the NAT64 gateway) is implemented in the network. The
other component, the CLAT, is located on the end-user device itself.

If the end-user device doesn't have a CLAT implementation, it will be
able to access the IPv4 internet using DNS64/NAT64. So, for the record,
this is the network type I would like to see be the default; IPv6-only
on the LAN itself, but with DNS64 and NAT64 service somewhere in the
upstream network. And yes, I am fully aware that this would preclude all
current Android devices from connecting to it without configuring some
manual network settings.

> But for the rest of us, just about all people at the meeting,
> 464XLAT provides access to IPv4 like any other NAT implementation.
> Anyone who is still firmly stuck in supporting just the legacy
> protocol will have no problems with such a network. It does not
> encourage any of the RIPE members to do anything.

You never know. The RIPE meeting is regularly attended by folks who are
working for the vendors and are actually in a position to do something
about various bugs. We also have a opensource wg and lots of skilled
techies which could potentially find the extra motivation they need to
actually go and fix bugs or shortcomings in open-source projects.

It's far from a certainty, of course, but if I've learned one thing from
when I was repeatedly pestering vendors to fix various «IPv6 brokenness»
issues it's that it actually has an effect to highlight an issue over
and over again if you want to see it fixed.

> Worse, suppose someone has spend a lot of time making sure that his 
> network supports IPv6 in every possible way, shows up at a RIPE 
> meeting with an Android phone and finds that he doesn't have network
> access. Not because of some IPv6 issue. No, because the network is 
> deliberately set up in a way that is incompatible with Android. Not 
> good.

If you look at Răzvan's slides at
https://ripe68.ripe.net/presentations/505-RIPE_68_Technical_Report.pdf,
you'll see that 33% of all clients were using the fallback "ripemtg-2.4"
network. Presumably they did so out of necessity - at least I can think
of no good explanation why anyone would deliberately choose a
non-default 2.4GHz network if they had the option of choosing the
default interference-free 5GHz network instead.

So at RIPE68, the network was apparently deliberately set up in a way
that was incompatible with one-third of the clients. Not good? Well,
from what I can tell, this appears to have been completely uncontroversial!

If I again look at Răzvan's slides, I see that Android was only 16% of
all the clients. So what I struggle to understand is why it would be so
terrible to set up the network in a way that is incompatible with 16% of
the clients, while at the same time setting it up in a way that is
incompatible with 33% of the clients is totally fine?

Clearly, the viability of both approaches would depend entirely on the
availability of a fallback network where the incompatible clients could
connect instead. That was in place at RIPE68, and I'm certainly not
proposing to take that away.

> Now it would be eating our own dog food if there were a RIPE BCP 
> publication that states that the best way to provide IPv4 on a modern
> wifi is NAT64. However, as far as I know, there is no such document,
> no plans for it, and I would be surprised major wifi hotspot would
> want to move to 464XLAT. But you never know.

We are talking about the RIPE meeting here, not a random wifi hotspot at
your local coffee shop or wherever. We're the ones actually insisting
that others to go do this IPv6 thing, so we should really be at the
forefront of such efforts ourselves. If the BCP you're describing is to
ever be written, we can't expect that a coffee shop, airport or whatever
will provide the deployment experience on which such a document could be
based - the RIPE meeting, on the other hand, would be a perfect fit.

Tore