> subscribers, if the sparse allocation is implemented? > > If the answer is around /20 or so, I guess /12 is OK for IANA-RIR > allocation size. Q: how many allocations can there be of /12s? A: 512 Q: from the view of address space conservation, is this prudent? A: possibly it is not Q: but isn't ipv6 address space effectively enormous? A: 64 bits are being used for a host identifier, so it is half as long as you think at first randy