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That's fair enough, in which case ipv6 is really only a /76 (having more than 1000 hosts on a subnet isn't a great thing, even with no broadcast and arp and other traffic, and /76 allows 4000 on a /64)

Those fanboys going "we'll never run out of 2^128 IPs" are being disingenuous when about 2^59 of them have been burnt straight away (I'd guess most subnets have less than 30 devices)

2^64 subnets is a reasonable number, but when they are handed out like candy that number dwindles quickly. ARIN is allocating the equivalent of a /15 every year. That's fine if it's a constant allocation, there's 100,000 years worth, but if that rate grows, the space will be eaten in a matter of a few decades.




It's not being burnt, there are two useful things we're doing with the 64-bit network size:

* Sparse networks. 64 bits is too big to feasibly do a brute force scan on, which reduces how often servers get exploited by random network attacks. * SEND secures NDP by using those 64 bits for a public key

Reducing network sizes to 12 bits would destroy both advantages.




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