* antli...@youngman.org.uk: > An ISP will then be allocated the next 16 bits, giving them a 32-bit > address space to allocate to their customers - each ISP will have an > address space the size of IPv4?!
ISPs can ask for several address spaces, each of which had a much, *much* larger address space than the whole of IPv4. My ISP (Deutsche Telekom) assigns /56 Subnets to Home Routers. Given that an IPv6 address encompasses 128 Bits, each household is thus provided with an address space of 2^(128-56) Bits. The whole of IPv4 spans only 2^32 Bits. Any halfway decent data center should, at least, hand out /64 Subnets for each and every hardware server and VM, free of charge. With virtu- alisation becoming mainstream, I'd prefer to have a /56 for the host server, so I can assign /64 subnets to each VM. A wider address space does not mean one makes use of every available address, of course. It just makes routing that much simpler, and there is no need for silly stuff like NAT. -Ralph
