alt Hacker News> We can't have globally routable, unique, random-esque ID precisely because it has to be hierarchical
This is not, technically, true. We could have globally-routable, unique, random-esque IDs if every routing device in the network had the capacity to store and switch on a full table of those IDs.
I'm not saying this is feasible, mind you, just that it's not impossible.
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It isn't just storage - lookup in those tables needs to be usefully fast.
I guess it depends on what you mean by "impossible." If you only mean that it's theoretically possible, then sure, one can imagine a world where that is done. But even with IPv4's meager 32 bits of address space, it would explode TCAM requirements on routers if routers would start accepting announcements of /32s instead of the /24s that are accepted now. And /64 (or, jesus, /128) for IPv6? That's impossible.
And if anti-gravity existed, we could have flying cars.
Outside of ignoring the laws of physics, this isn’t very useful of speculation.
You would also need something like O(N²) routing update messages to keep those tables updated, instead of the current... I'm guessing it grows more like O(log N) in the number of hosts. So everyone would need vast amounts of CPU and bandwidth to keep up with the announcements.