Basically what the title says. Here’s the thing: address exhaustion is a solved problem. NAT already took care of this via RFC 1631. While initially presented as a temporary fix, anyone who thinks it’s going anywhere at this point is simply wrong. Something might replace IPv4 as the default at some point, but it’s not going to be IPv6.
And then there are the downsides of IPv6:
- Not all legacy equipment likes IPv6. Yes, there’s a lot of it out there.
- “Nobody” remembers an IPv6 address. I know my IPv4 address, and I’m sure many others do too. Do you know your IPv6 address, though?
- Everything already supports IPv4
- For IPv6 to fully replace IPv4, practically everything needs to move over. De facto standards don’t change very easily. There’s a reason why QWERTY keyboards, ASCII character tables, and E-mail are still around, despite alternatives technically being “better”.
- Dealing with dual network stacks in the interim is annoying.
Sure, IPv6 is nice and all. But as an addition rather than as a replacement. I’ve disabled it by default for the past 10 years, as it tends to clutter up my ifconfig overview, and I’ve had no ill effects.
Source: Network engineer.
IPv6 isn’t just larger addresses, it was meant to totally remove the need for layer 2 / MAC addresses, bus networks, DHCP, and broadcasts. Since the plan was to get rid of the 12 byte ethernet header, the 24 byte increase in IP addresses would only be a 12 byte increase in header at the end of the day. WiFi wouldn’t need three MAC addresses in every packet. IPv6 only achieves it’s true potential with a complete switch over.
I personally don’t think that can ever happen. The opportunity to switch everyone over is absolutely long gone. IPv6 isn’t an extension of v4 or a compatible replacement, like ASCII to UTF-8. It’s more like X to Wayland. The protocol authors went “This is a mess we gotta rethink this from scratch”. But there’s so much already relying on the old protocol, and replacing it with something that doesn’t perfectly match features is difficult for little reward for users.
The increase in IPv6 nodes has mostly been due to mobile networks. The tragedy is they actually still mostly use layer 2 and bridge networking. IPv4 nor v6 can handle maintaining connections while addresses change. So they set it up so that you keep the same IP address as you travel and move between different towers. This is done with massive virtual layer 2 LANs across towers, with the IP routing happening at a central datacentre. IPv6 is simply used for the larger addresses, and none of the network/protocol simplifications it promised can be used.