T-Mobile’s path to IPv6 Only

What people said

MrRadar · 2017-06 · Recommendation

It's interesting how his chart deflects somewhere around 80%, since at the 2017 Rocky Mountain IPv6 Summit that's about where T-Mobile US (who probably have the highest penetration of IPv6-capable endpoints of any ISP) noted their transition started slowing drastically.[0] The main reasons are that the remaining devices are old (e.g. 3G phones), have limited capabilities/needs (e.g. embedded IoT devices which just need to phone home once in a while), or are using odd configurations (e.g. for some reason T-Mobile doesn't currently support IPv6 for tethering). Another good talk from that conference is about how Carrier Grade NATs are (amazingly) even worse in practice than they sound in theory[1]. During the Q&A portion one of the audience members points out that as technologies like CGN become required to provide IPv4 service it will cause the cost of supporting IPv4 to rise over time and naturally push ISPs to kill IPv4 as the use of v4 drops while the costs to support it do not. I can also recommend a short talk by Cloudflare about their experience serving IPv6 traffic[2] and another on the history and future of IPv6[3]. [0] [VIDEO] [1] [LINK] [2] [LINK] [3] [LINK]

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throw0101a · 2025-11 · Reference

> Isn’t essentially the entire US on CG-NAT for IPv4 on mobile data? T-Mobile, for one, has had their handsets IPv6-only for a few years, so if your Android/iOS does a DNS lookup and gets an AAAA record back, it will skip CG-NAT. T-Mobile presenting at NANOG in 2018 on IPv6: * [LINK] And Rocky Mountain IPv6 Taskforce in 2017: * [VIDEO] Further data: > Chances are if you use the Internet on your smartphone, you are connecting via IPv6. According to the Internet Society’s 2018 State of IPv6 Deployment,[1] 80% of smartphones in the US on the major cellular network operators use IPv6 and major mobile networks are driving IPv6 adoption with Verizon Wireless at 84%, Sprint at 70%, T-Mobile USA at 93%, and AT&T Wireless at 57%. Plus, some mobile networks are taking the step to run IPv6-only to simplify network operations and reduce costs. * [LINK] Though some folks aren't happy with the implementation: > But from my own experience, neither T-Mobile nor AT&T allows inbound traffic to the phone's IPv6 address. This negates some of the advantages of having a globally routable IPv6 address. * [LINK]

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throw0101d · 2025-08 · Reference

Trying to re-engine a 747 in mid-air is a challenging operation. > So IPv6 is about 30 years old, and the testimony being shared is the chair of the group spending years of research and millions of dollars, finally launching ipv6 corporate lans in 2023. And how many years of research and millions of dollars was spent in the 1990s on IPv4? People used to use workstations as routers (e.g., see SunOS routeadm(1M)) and DNS caching servers before a lot of money was poured into ASICs for routing (and switching). There are all sorts of dumbass things with IPv4: how much time has been wasted on engineering solutions around NAT (e.g., STUN/TURN/ICE)? But because IPv4 just happens to be the default we accept them as 'normal' and anything that is different is treated as 'abnormal'. > You're not selling me on it's viability. I'm not sure how it's not viable given there are mobile telco networks with tens (hundreds?) of millions of people getting only IPv6 addresses on their devices. * [VIDEO] * [LINK] There are some folks who (a) were lucky enough to get in early on the IPv4 address land rush, or (b) are rich enough to be able to purchase IPv4 addresses, but there are also (c) plenty of folks who are left with scraps for IPv4 connectivity. The fact that you happen to fall into (a) or (b) does not mean you get to dismiss the folks in (c) who need IPv6, as otherwise they'd have no connectivity at all.

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