Schrödinger's IPv6 Cat (opens in new tab)

My company would only ask for IPv6 if a software doesn't support IPv6 though.

Sonic (beloved Bay Area ISP) got pestered with requests for IPv6, until they finally natively implemented it for their fiber, even though they had 6rd tunnels before.

But granted, Sonic is favored by enthusiasts, so they likely have a higher share of customers caring about such technicalities. And even then the ratio of users actively asking for it may have been tiny.

Half of AWS services aren't even available from an IPv6 endpoint, it's a clusterfuck. I'm all for carrot and stick but they are making a giant mess of it.

Source: https://docs.aws.amazon.com/vpc/latest/userguide/aws-ipv6-su... , see 'IPv6 only support' column.

Having IPv4 just for your public facing servers is a small expense, and within the private network you can still use private IPv4. The biggest pressure is to allow your servers to call out into the internet without an IPv4 address or a NAT. That's pressure on APIs, SaaS services consumed by backend servers, update servers, etc.

Maybe that's enough to remove the friction around IPv6 and make it "just work" to the point that everyone just keeps it on. Or maybe it doesn't and we get a divide where everything consumed by machines moves to IPv6 while content consumed by humans keeps preferring IPv4.

Where I work there is almost nobody with any IPv6 experience and certainly nobody willing to come forth and push for adoption. We just push the increasing cost of NAT gateways etc onto our customers.

I doubt it. People will just start setting up load balancers with SNI routing if cost becomes a problem.

You can, with several caveats, detect which hop(s) on the path perform NAT by using some trickery [1]:

> NAT devices are detected by observing a difference in the expected and actual checksum of the UDP packet that is returned as the part of the Original Datagram in the ICMP Time Exceeded message. If they differ then it indicates that a NAT device has modified the packet. This happens because the NAT device must recalculate the UDP checksum after modifying the packet (i.e. translating the source port) and so the checksum in the UDP packet that is nested in the ICMP error may not, depending on the device, match the original checksum.

[1] https://github.com/fujiapple852/trippy/releases/tag/0.11.0

Check the IP that your router receives on its WAN interface and compare it to the IP printed by internet services like Google (search for "what is my ip" and there'll be a special card among the results) or https://ipinfo.io/ip . If they're not the same (because your router's IP is a private IP like 192.168.#.# or 10.#.#.#) then your router is being NAT'd.

The most reliable way is to compare your ISP-assigned address to the response from any one of a number of services that return the caller's IP address (e.g., https://checkip.amazonaws.com/).

Aside from comparing assigned public IP addresses regularly, I think we (ipinfo) probably have this data internally, or at least we can figure it out. We are pinging and running traceroutes on every IP out there to figure out IP geolocation, so I think we should be able to tag ASNs/ISPs that use CGNAT. So, on CGNAT connections the RTT on the same IP address will be different from time to time and traceroute paths and times will be different as well.

But I'm not sure who will and how they will find this information useful. If anyone can think of a reason why CGNAT detection can be useful generally, I can pitch this to the engineers.

Check the IPv4 address on your WAN. If it's in the 100.64.0.0/10 range [0], you're on CG-NAT.

Furthermore, run

    curl ipv4.icanhazip.com

If the address you get back is different from the one on your WAN interface - assuming your Gateway is your ISP rather than, say, a VPN - you must be on CG-NAT.

[0] https://en.wikipedia.org/wiki/Carrier-grade_NAT#Shared_addre...

I don't know of any ISP that will give you a public ipv4 address for free.

More interesting is windows 11 auto configuring ipv6. Does you pc have a public ipv6 address starting with 2:: or fe80:: link local address?

Quick ipv6 crash course. Instead of DHCPv4 (there is DHCPv6 but it's optional) being required for address configuations, ipv6 uses somting called Stateless address Autoconfiguration (SLAAC). Normaly your router sends out Router advertizments packets and this tells devices about the default gateway, public prefix, dns etc... and pc will generate a public ip of (64 bit public prefix):(64 bit random number).

It seems like Windows 10 and eariler will not do ipv6 unless your router advertises it.

TL;DR learning ipv6 is easier than disabling it at this point

Eyeballing a sigmoid curve fit to the google's IPv6 charts would support that.

I feel like lots of providers in Japan are using it now. MAP-E is awful, it doesn't use typical IPv6 acquisition methods and the ipv4 address/allowed forwarding ports are calculated based on the IPv6 address (using a public/fixed table?).

The Blob is a political insult towards the civil service by senior Tory leaders, who blamed them for resisting their policies for political reasons.

It does not refer to bureaucratic friction in general, and is not a term in widespread use by the British.

Wrong. It's more about money. People who run ISPs have said they don't support IPv6 because they won't see any return on the cost. These ISPs use CGNAT and like to solve customer "issues" by selling them a static IP. They would sell far fewer static IPs and actually have to look into issues rather than dilly dally around a bit so the static IP "fixes" the issue. They like to blame issues on other nefarious customers causing shared IPs to be banned or something like that.

This talking point has been debunked since the 90s. Any device capable of doing NAT can perform the even easier task of filtering packets.

Even if you do decide to toss your router and connect directly to the internet it’s a lot less risky than it was in 1998 when Windows 95 didn’t have a firewall. I doubt IPv6 is going to make many people decide they want dumber gateway devices, however, since the cost differential hasn’t been meaningful for ages.

They can use NAT on v6 if they really want to

I can see how you might suspect that, but I got a different read from it. The constant references to the topic as the "IPv6 Cat" struck me as another in the long tradition of authors who became too attached to a clumsy and ineffective analogy they thought was good enough™ and banged it like a drum. That strikes me as an all-too-human thing to do (especially since I've been guilty of it myself before) rather than an AI artifact. I enjoyed the piece nevertheless, and I agree with its premise that market forces are not enough to continue the trend of IPv6 penetration growth and that public policy carrots and sticks are both needed and justifiable to ensure it comes to pass.

On another matter, whose brainchild is IPv6+? I haven't heard of that one before.

Indeed!

Look at these formulations: "Respecting these governance frameworks is crucial to maintaining the open, collaborative model that underpins global Internet development and its technological evolution ... collaborative approaches that engage technical communities, promote open standards, and prioritise interoperability are essential... To overcome these challenges, a strategic approach combining economic and operational incentives with collaborative governance is essential. Governments and organisations must take proactive steps to create a more supportive environment... By combining these measures, enterprises and network operators can address the barriers to IPv6 adoption while fostering collaboration between governments, industry leaders, and the technical community. This approach ensures that the transition to IPv6 remains inclusive, efficient, and aligned with the Internet’s principles of openness and innovation."

Purely LLM gibberish...:))

"seamless", appearing 5 times.

Everything is "seamless" with ChatGPT.

IPv6 is seamless, etc...

I've never seen anyone explain a "straightforward" way to extend the bits without having 90% of the same adoption difficulty. What's your idea, specifically?

Also extension mechanisms like that already exist as part of ipv6.