IPv6 Address Formats

IPv6 addresses are 128-bit entities. IPv4 addresses are 32-bit addresses normally written as four decimal numbers (dotted decimal), one for each byte of the address.

Example: 192.1.2.34

IPv6 Node Addresses are 128-bit records represented as eight fields of up to four hexadecimal digits. A colon separates each field (:). Example: 3ffe:ffff:101::230:6eff:fe04:d9ff.

	NOTE: The symbol “::” is a special syntax that can be used as a shorthand way of representing multiple 16-bit groups of contiguous 0’s (zeros). The “::” can appear anywhere in the address; however it can only appear once in the address.

To indicate a subnetwork address, IPv6 uses subnet prefixes similar to IPv4 CIDR format. Figure 6-1 “IPv6 128-bit Addresses; HP-UX Default Prefix 64”shows a 128-bit IPv6 node address with a 64-bit subnet prefix.

Figure 6-1 IPv6 128-bit Addresses; HP-UX Default Prefix 64

An IPv6 node address and its subnet prefix length can be combined in the following format:

<IPv6-Node-Address>/<Prefix-Length>

Where <IPv6-Node-Address> is an IPv6 address and <Prefix-Length> is a decimal value specifying how many of the leftmost contiguous bits of the address compose the subnet prefix.

In Figure 6-2 “Example Prefix Length 48”, prefix length 48 specifies that the leftmost 48 bits of the IPv6 address compose the subnet prefix.

Figure 6-2 Example Prefix Length 48

Address Scope

Link-local

An IPv6 addres s used on a single link.

Global

An IPv6 address that uniquely identifies a node on the Internet such that packets can be routed to the node from any other node on the Internet.

Address Type

Unicast

Identifies a single interface. Notable unicast addresses are:

Loopback

::1 Address internal to IPv6 stack

Unspecified

:: Not a legally defined address

Anycast

Identifies a group of interfaces, possibly belonging to different nodes. A packet sent to an anycast address is delivered to only one of the interfaces in the group. Anycast addresses are currently not supported by HP-UX 11i v2 IPv6.

Multicast

Identifies a group of interfaces, possibly belonging to different nodes. A packet sent to a multicast address is delivered to all the interfaces in this group.