The interface ID is generally set to 64 bits in the EUI-64 format, and is generated by automatically manipulating the MAC address of the interface. Three types of addresses Unicast - identifier for a single interface. Multicast - identifier for a set of interfaces. A packet sent to multicast address is delivered to all members of the set. All multicast addresses begin with FF , and the fourth address place defines the addresses scope.
Permanent addresses are multicast addresses with a defined meaning.
Non-permanent multicast addresses can be created from a reserved address space, equal in size to IPv4's total address space. Anycast - identifier for a set of interfaces. Unicast addresses that have been assigned to more than one interface, and interface ID is set to zero. Within that subnet, each interface must be identified by a unique unicast address. Scope Scope defines the area in which a unicast address is valid.