A unicast address is an identifier for an interface. Packets sent to a unicast address are delivered to the node containing the interface identified by the address.

LAN unicast addresses typically have the following format:

If the site or organization needs to divide the subnet further, then the following format is used:

 

The following addresses decribes commonly used unicast addresses and their values:

Unspecified address

Indicates the absence of an address, and is never assigned to an interface. The unspecified address has the value 0:0:0:0:0:0:0:0 in the normal form or :: in the compressed form.

Loopback address

Used by a node to send IP datagrams to itself, and is typically assigned to the loopback interface. The IPv6 loopback address has the value 0:0:0:0:0:0:0:1 in the normal form or ::1 in the compressed form.

IPv6 addresses with embedded IPv4 addresses

Used in mixed IPv4 and IPv6 environments, and can be either of the following:

- IPv4-compatible IPv6 address

Used by IPv6 nodes to tunnel IPv6 packets across an IPv4 routing infrastructure. The IPv4 address is carried in the low-order 32-bits. The format of this address is as follows:

Used to represent an IPv4 address and to identify nodes that do not support IPv6 (IPv4-only nodes). It is not used in an IPv6 packet. The format of this address is as follows:

Local-use IPv6 unicast addresses

Can be either of the following:

Link-local

Used for addressing on a single link when performing address autoconfiguration, neighbor discovery, or when no routers are present. The format of this address is as follows:

Site-local

Used for sites or organizations that are not connected to the global Internet. The format of this address is as follows: