IPv6 Addresses
Address Space

The huge IPv6 address space was divided into several groups (types of addresses) and each group associates addresses with a common characteristic. Addresses can be assigned to individual groups based on the prefix. Basic classification of addresses is in the following table.

The Basic Classification of Addresses

IPv6 notation

Address type

::/128

Unspecified Address

::1/128

Loopback

FC00::/7

Unique-Local Unicast Addresses

FE80::/10

Link-Local Unicast Addresses

FF00::/8

Multicast Addresses

Everything else

Global Unicast Addresses

Global Unicast addresses occupy the vast of majority of address space. These addresses are taken only from the prefix 2000::/3 today. Other prefixes are reserved for future use.

Anycast addresses are not taken from its own address space. They are taken from the same address space as well as Global Unicast addresses and are not syntactically distinguishable from unicast addresses.

Several small areas of address space were assigned a special meaning. The whole prefix ::/8 that is reserved for those areas is declared as unassigned. However, some addresses were taken from this prefix. They are ::0 and ::1. ::0 address is used when no IPv6 address is assigned to the interface. This address is called Unspecified. ::1 address is used as Loopback. This address is equivalent of 127.0.0.1 for IPv4.

Another group identifies the addresses with a limited range: