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.
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: