Mans Nilsson wrote:
With proper layering, network addresses including IP ones, certainly, uniquely identify *hosts*.
However, with proper layering, *applications* only require uniqueness of IP+Port, which is enough for the worldwide IPv4 network.
As a result, NAT won the battle against IPv6.
IPv6 addresses are free but useless.
With all due respect, you think about networks. I use and build networks. And my experience is that IP+port is not enough.
Certainly, local uniqueness of IP addresses to identify hosts is required even in private networks behind NAT. But, because of layering, that's all. I do have extensive experiences to use and build networks with proper layering in mind.
We cope, because a lot of technical debt is amassed in corporate and ISP / access provider networks that won't change.
Sounds like abstract nonsense.
We don't cope because NAT is good. Hardly a workday goes past without me thinking "If I could address this computer uniquely I'd go home earlier and with less grey hair".
The reality is that application servers only need globally unique and stable IP+Ports. You can address application servers with them.
We must do better.
As IPv6 is worse than IPv4 with NAT, feel free to propose a new network protocol. Masataka Ohta