[notdonspaulding]

To the best of my knowledge, Comcast is running dual-stack v4 and v6. The GP was talking about running a purely v6 network, and pointing out that it wasn't yet feasible. Your example of Comcast doesn't really fit the bill because Comcast already has a v4 network to all of their customers, and they are not migrating customers to a solely-v6 network.

This is the chicken-and-egg problem that all new networks are facing with regard to IPv6 adoption. In order to have a usable network, you have to support IPv4 to all endpoints. But once you have v4 at all endpoints, the incentive to run v6 is greatly diminished.

As always, v6 needs a "killer app" that Grandma wants to use that is unavailable over the v4 internet, and then network administrators could use the actual demand from their customers as a justification for moving to v6. Unfortunately, at the moment, the list of v4-only must-have apps is still greater than the list of v6-only must-have apps.

[throw0101a]

> The GP was talking about running a purely v6 network, and pointing out that it wasn't yet feasible.

Amusingly that's how mobile/smartphones are supposedly run: the devices get IPv6-only, and if they need to hit an IPv4-only address they are CGNATed.

* https://www.internetsociety.org/resources/deploy360/2014/cas...

* https://blogs.akamai.com/2016/06/preparing-for-ipv6-only-mob...

[exhilaration]

Ah, so that explains it. I just switched from Sprint (which always gave me an IPv4 address) to T-Mobile (which gives me an IPv6 address).

[jaywalk]

My Verizon iPhone has both a public IPv4 address and a public IPv6 address.

They certainly could be using CGNAT, but that seems like a weird way to do it.

[throw0101a]

> My Verizon iPhone has both a public IPv4 address and a public IPv6 address.

How are you able to tell with IPv4? You cannot run ifconfig on an iPhone, so how are you determining that?

[kalleboo]

There are apps like "Network Analyzer" that give you this info. (My MVNO puts me behind CGNAT, no IPv6)

[briffle]

Seriously? On Android it's just settings->about phone

[wPfMiPmvaXQxERm]

Really? My Verizon Android gets RFC6598 space.

[jaywalk]

Holy cow, I don't know how I was never aware of RFC6598. When I saw the address starting with 100, I simply assumed it was an actual routable IP.

[wmf]

v6 with DS-Lite/464/MAP is going to be cheaper than v4-only because it allows the ISP to sell off (or not buy) most of their v4 addresses while also using less equipment. T-Mobile has already adopted this architecture.