- A. ICANN
- B. APNIC
- C. RIR
- D. ISPs
Before going forward that far it is important to note that like IPv4, the placement of the devices that will be allocated with IPv6 addresses can affect the numbers and the method of assignment.
If the IPv6 addresses in question will be used solely for the internal purposes of a business and do not need to be directly routable to the public Internet, then the
Unique Local IPv6 range (RFC 4193) and assignment method can be used; these would be the equivalent of RFC 1918 IPv4 private address ranges. If, however, the IPv6 addresses are intended to be directly routable on the public Internet, a range must be assigned (just like with IPv4) by an Internet Service Provider (ISP), or a Regional Internet Registry (RIR) if allocating for an ISP.
As of this writing, the Unique Local address range includes all addresses that fall under the FC00::/7 prefix (they begin with 1111110 in binary), while the Global
Unicast address range includes all addresses that fall under the 2000::/3 prefix (they begin with 001 in binary). Global Unicast ranges are divided by a number of different entities; at the top of these entities is Internet Corporation for Assigned Names and Numbers (ICANN) who assigns addresses to the RIRs (for all regional registries except APNIC), who will in turn assign addresses to ISPs who will in turn assign addresses to End Users (EU).