Ha, I guess this is one way of summarizing it :) Author here. I wanted to share more subtleties of the design, but maybe I failed.

Indeed, the starting point is sharing IP's across servers with port-ranges.

But there is more:

* awesome performance allowed by anycast.

* ability to route /32 instead of /24 per datacenter.

Generally, with this tech we can have much better IP usage density, without sacrificing reliability or performance. You can call it "global anycast-based stateless NAT" but that often implies some magic router configuration, which we don't have.

Here's one example of problems we run into - the lack of connectx() syscall on Linux - makes it hard to actually select port range to originate connections from:

https://blog.cloudflare.com/how-to-stop-running-out-of-ephem...