The world in which IPv6 was a good design (2017)

> Now, if only we could get jumbogram more widely deployed. Thats older than V6 is and still struggling to break the 1500 byte MTU limit.

Really, we barely hit 1500. Look at mss for popular websites, most people drop from 1500, because 1500 has problems in enough places. Does http/3 even send 1500 byte packets ever?

One major problem is most servers (Linux all versions, I think, FreeBSD before about 2000 and after something like 2019) always send the interface mss with a syn+ack. You get meaningfully better results by sending the lesser of the interface mss and the received mss; there are enough broken systems out there that don't communicate the real MTU to end systems[1], don't send enough ICMP needs frags, try to cover it up by manipulating mss in syns, but don't manipulate mss in syn+ack. Windows and iOS (and presumably mac) do a pretty good job of detecting pmtud blackholes, but it's often disabled on servers and I can't remember where Android is these days; I know it used to ship with the option compiled in but disabled and no way to enable.

Of course, packet sizing is actually a hard problem. Larger packets are good for faster links but bad for slower links.

[1] which is hard, because I don't know how you get windows to use MTU from dhcp; it doesn't request it, so it won't use it. This is a problem too.

The author would have liked Xerox Network Services. The Xerox plan was that devices had a 48-bit Ethernet address, and local area networks had a 32-bit network ID. Routing was by network ID until the packet hit the final LAN. No need for IP-level addressing.

Early Stanford and PARC routers could route XNS packets, but this died out some time in the 1980s.

Yes, it's a common idea but relies on a misunderstanding - it would have required exactly the same difficulty as switching to IPv6, because there's no way to make an 'ipv4 with more bits' compatible with regular IPv4 software or hardware, without changing to a dual stack arrangement (which requires replacing all the packet processing hardware in big routers that relies on the layout of the IP header) - exactly the same problem we had with IPv6.

Is it such a myth, though?

IPv6 still causes troubles in deployment.

For example, Android phones (still!!!) don't support stateful DHCPv6. Moreover, DHCPv6 was designed by idiots and out of many options for DUIDs it doesn't allow the most logical one: a user-specified host name.

PMTU in IPv6 is even _more_ broken than in V4 because extension headers just plain don't work in the wide Internet.

AWS will start charging for most IPV4 addresses next year [1]. And I'd expect other cloud providers to follow AWS' lead here.

This could provide the needed push for the Industry to switch.

[1] https://aws.amazon.com/blogs/aws/new-aws-public-ipv4-address...