IPv6 was built for a world with 64 bit machines. That's why the address is basically two 64 bit chunks, the first being the global network and the second being

IPv6 was built for a world with 64 bit machines. That's why the address is basically two 64 bit chunks, the first being the global network and the second being the local network. This is why you never allocate an IPv6 network smaller than a /64, so router manufacturers can optimize their hardware to only have to examine the half of the packet that the current routing step cares about.