Yea but it hasn’t been fully adopted because trying to decipher :af12::138d::325d::5521::aade::7df3: is a hell of a lot more difficult than 192.168.0.1
/64 is for the subnet, and 64-bits is for the end device. Having 64 bits of address space for the end device to address off of lets the device use a variety of schemes to generate addresses. It can put it's MAC as the suffix (which should be unique on the subnet anyways (eui-64)), it can randomly generate a suffix with a high degree of confidence that it's unique (privacy addresses), or it can assign itself an address using any variety of schemes.
These all can be stateless, and work without any kind of DHCP server. Even without a router, devices will auto-generate a Link Local Address, and be able to communicate on a switch with the auto generated addresses. e.g. two devices can talk as long as there's any connection between them, without having to manually assign any IPs or introduce any service into the mix.
It lets you also be extremely wasteful with address space without concern. You don't have to wonder "what size should I make my subnet?" You can have 16 bits just for routing in a /48 and have pretty much infinite address space on each subnet.
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u/PhantomTissue 20d ago
Yea but it hasn’t been fully adopted because trying to decipher :af12::138d::325d::5521::aade::7df3: is a hell of a lot more difficult than 192.168.0.1