The network prefix (the routing prefix combined with the subnet id) is contained in the most significant 64 bits of the address. General unicast address format (routing prefix size varies) Unicast and anycast addresses are typically composed of two logical parts: a 64-bit network prefix used for routing, and a 64-bit interface identifier used to identify a host's network interface.

For each of the major addressing and routing methodologies, various address formats are recognized by dividing the 128 address bits into bit groups and using established rules for associating the values of these bit groups with special addressing features. However, the use of the all-nodes group is not recommended, and most IPv6 protocols use a dedicated link-local multicast group to avoid disturbing every interface in the network.Īn IPv6 address consists of 128 bits. Broadcast's traditional role is subsumed by multicast addressing to the all-nodes link-local multicast group ff02::1. IPv6 does not implement broadcast addressing. A packet that is sent to a multicast address is delivered to all interfaces that have joined the corresponding multicast group. Almost any unicast address can be employed as an anycast address.Ī multicast address is also used by multiple hosts that acquire the multicast address destination by participating in the multicast distribution protocol among the network routers. Anycast addresses cannot be identified easily, they have the same format as unicast addresses, and differ only by their presence in the network at multiple points. A packet sent to an anycast address is delivered to just one of the member interfaces, typically the nearest host, according to the routing protocol's definition of distance.

The Internet Protocol delivers packets sent to a unicast address to that specific interface.Īn anycast address is assigned to a group of interfaces, usually belonging to different nodes. Ī unicast address identifies a single network interface. IPv6 addresses are classified by the primary addressing and routing methodologies common in networking: unicast addressing, anycast addressing, and multicast addressing. Therefore, in comparison, IPv6 has a vastly enlarged address space. In contrast to IPv4, which defined an IP address as a 32-bit value, IPv6 addresses have a size of 128 bits.

IPv6 is the successor to the first addressing infrastructure of the Internet, Internet Protocol version 4 (IPv4). The IP address of the destination is used to make decisions about routing IP packets to other networks. IP addresses are included in the packet header to indicate the source and the destination of each packet. Label to identify a network interface of a computer or other network node Decomposition of an IPv6 address into its binary formĪn Internet Protocol Version 6 address ( IPv6 address) is a numeric label that is used to identify and locate a network interface of a computer or a network node participating in a computer network using IPv6.

Rules for compressing ipv6 addresses