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The TCP/IP Guide  9  TCP/IP Lower-Layer (Interface, Internet and Transport) Protocols (OSI Layers 2, 3 and 4)       9  TCP/IP Internet Layer (OSI Network Layer) Protocols            9  Internet Protocol (IP/IPv4, IPng/IPv6) and IP-Related Protocols (IP NAT, IPSec, Mobile IP)                 9  Internet Protocol Version 6 (IPv6) / IP Next Generation (IPng)                      9  IPv6 Addressing

IPv6 Address and Address Notation and Prefix Representation 1 2 3 IPv6 Global Unicast Address Format

Current IPv6 Address Space Allocation Plans

The allocation of different parts of the address space still is done based on particular patterns of the first three to ten bits of the address, to allow certain categories to have more addresses than others. The elimination of the specific term denoting this is intended to convey that these bits should not be given “special attention”.

Table 60 shows the allocations of the IPv6 address space, and what fraction of the total address space each represents:

This is more complicated than the IPv4 “classful” scheme because there are so many more categories and they range greatly in size, however, most of them are unassigned at the present time.

IPv6 Address and Address Notation and Prefix Representation 1 2 3 IPv6 Global Unicast Address Format