An Internet Protocol Version 6 address (IPv6 addressing) is a numerical label that is used to identify a network interface of a computer or other network node participating in an IPv6 addressing-enabled computer network.
IP addresses serve the purpose of uniquely identifying the individual network interface(s) of a host, locating it on the network, and thus permitting the routing of IP packets between hosts. For routing, IP addresses are present in fields of the packet header where they indicate source and destination of the packet.
IPv6 addressing is the successor to the Internet’s first addressing infrastructure, Internet Protocol version 4 (IPv4). In contrast to IPv4, which defined an IP address as a 32-bit number, IPv6 addressing has a size of 128 bits, vastly expanding the addressing capability of the Internet Protocol.
IPv6 addressing is classified by the primary addressing and routing methodologies common in networking as follows
- An unicast address identifies a single network interface.
- An any cast address is assigned to a group of interfaces.
- A multicast address is also used by multiple hosts.
IPv6 addressing does not implement broadcast addressing, the use of the all-nodes group is not recommended, and most IPv6 addressing protocols use a dedicated link-local multicast group to avoid disturbing every interface in the network.