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Comment by crims0n | Hacker News Reader

Obligatory IPv6 is an academic solution to an engineering problem.

It was developed by the IETF in a working group led by engineers from Cisco and Nokia. It’s approximately as far from an academic solution as you can get.

An engineer would have preferred to add an additional byte (255.255.255.255.255) if the issue was really about addressing.

Exactly like we did with telephone numbers.

No. IPv6 is significantly easier to subnet. I can tell you the start and finish of 2a07:ffdd::/29 from the top of my head (it's 2a07:ffd8:: - 2a07:ffdf:ffff.....), because there's a nibble boundary every 4 bits, which makes it trivial.

IPv6 has 31 nibble boundaries. IPv4 has 3.

Do me a 10.15.121.75/19 from the top of your head.

I would choose working with IPv6 addresses over IPv4 any time of day.

Engineers added 12 additional bytes requiring the switch to a hexadecimal notation, because 255.255.255.255.255.255.255.255.255.255.255.255.255.255.255.255 would be a little bit too long.

No it isn't.

Not literally no, but the spirit of the sentiment is true. Have been in some flavor of networking for the past decade, there is a reason it hasn’t been universally adopted despite being ratified 25 years ago.

We can say that IPv6 is universally adopted for mobile networks.

But does it universally go IPv6 to IPv6 or IPv6 to an NAT64 gateway? Isn't CGNAT also popular for mobile networks?

Most of the traffic in mobile operator networks I'm aware of is IPv6 to IPv6, for very obvious reason - people watching youtube, facebook et al, and they are IPv6 enabled for over 10+ years. Of course one need to provide IPv4 reach-ability as well, details are varies from network to network, 464XLAT is being a popular one.

The big reason mobile networks use IPv6 is that they are new and don't have the IPv4 allocations of legacy providers. They could have gone CGNAT, but IPv6 with 464XLAT is better. Mobile networks are easier to use IPv6 than home networks since there is no customer gateway to worry about and 464XLAT software is included on device.

It's "popular" in that it's widely deployed, but I think it's fairly unpopular in that people really don't enjoy operating it. When I worked for a high traffic website, I was told people would occasionally reach out like "hey can we just ipv6-peer with y'all so our users don't have to talk to you over our cgnat. it's putting a ton of load on the cgnat gateway".

No one who operates a CGNAT enjoys it or wants to operate a CGNAT. I'd wager that most mobile network traffic is native IPv6 to IPv6 because all of the super high volume FAANG et al websites are operating IPv6.

CGNAT is a set of hacks on top of another set of hacks. You can keep stacking NAT on top of NAT for near-infinite amount of IP addresses, but what you can't do is you can't multiply the number of ports.

Before I switched ISPs, my home ISP was using CGNAT with no IPv6. It was trivial to completely screw up the connectivity for myself (and probably a lot of other users) by simply running a BitTorrent client with connection limit disabled.

Popular? Yes. A good solution? Definitely not.

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