No. There are 2^128 or so possible IP addresses. Such an index wouldn't fit anywhere. I think you're thinking of 6to4, which maps a /64 onto every v4 address.

No. There are 2^128 or so possible IP addresses. Such an index wouldn't fit anywhere. I think you're thinking of 6to4, which maps a /64 onto every v4 address. But allocation within the /64 may still be super sparse...