[lambda]

You could never recover 10/8. Simply impossible. Due to the fact that IP address space is running out, 10/8 what everyone uses for NAT; how are you going to solve the address exhaustion problem by removing the main tool people are using to fight it?

Well before that, you could recover 18/8, MIT's prefix; how many addresses does a single university actually need, even MIT? Stanford already returned their /8 prefix. Or you could potentially recover a variety of DoD /8s, or start assigning some of the ones that are "reserved for future use" like 240/4.

Of course, an even better use of 240/4 would have been to use it as a backwards-compatible way to move to a larger address space. IPv6 should have been specified with IPv4 compatibility via NAT from the beginning, so that it could be a gradual migration. I mean, we're moving that way anyhow, but with a much more painful period in the middle in which NAT is necessary but IPv6 isn't ready yet for people who want to end the pain of NAT.

[AnthonyMouse]

> start assigning some of the ones that are "reserved for future use" like 240/4.

The 240 block is problematic because a huge amount of legacy routing equipment is hard-coded to blackhole it. The best thing for it is probably to reserve it for unspecified local use, which would allow you to use it to NAT IPv6 addresses into locally, or use as additional RFC1918-style address space, or as ORCHID-style address space for IPv4-only applications using the likes of cjdns, etc.