An IPv6 address is made up of 128 bits divided into eight fields. Addresses can be represented using one of two formats:
The standard form is x:x:x:x:x:x:x:x where "x" represents one of the eight 16-bit fields of the address. Leading zeros can be dropped, but not trailing zeros. At least one digit is required in each field.
The compressed form uses "::" to indicate one or more consecutive fields containing zeros. The "::" can be used only once in an address.
The following are all valid IPv6 addresses:
BEA9:A032:0:0:4367:8A9C:0:847
BEA9:A032::4367:8A9C:0:847
A variable number of bits in an IPv6 address identify the subnet prefix. The remaining bits are the node's interface identifier, which must be unique across the link. The notation used for a prefix is similar to the CIDR notation used with IPv4: <IPv6 address>/<prefix length>, where prefix length is a decimal value identifying how many of the leftmost contiguous bits of the address represent the prefix.
Address compression can be used in a prefix, and a node's address and subnet prefix can be combined in one statement. The prefix AB83:0:32:EF6 can be identified as shown in the following examples:
AB83:0:32:EF60:0:0:0:0/60
AB83:0:32:EF60::/60
AB83:0:32:EF60::19D:4873/60
AB:06:A3:00
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NOTE: Supports assigning unique IPv6 prefix per individual mobile by incrementing IPv6-Prefix. |
An IPv6 node can have several different types of addresses assigned to each of its interfaces.
A unicast address is an identifier for a single interface on a single node. A packet sent to a unicast address is delivered to the interface specified. Special prefixes can be used for unicast addresses in a private network.
FE80::/10 identifies a link-local unicast address.
FEC0::/10 identifies a site-local unicast address
An anycast address is an identifier for a set of interfaces, typically routers, on a link. It is formed by the subnet prefix combined with zeros for the interface identifier. A packet sent to an anycast address is delivered to the closest (in terms of routing) interface.
A multicast address is similar to an anycast address in that it identifies a set of interfaces, but a multicast can contain hosts and routers. A packet sent to a multicast address is delivered to all interfaces identified by that address.
The first 64 bits and the last 32 bits of the starting IPv6 address must be unique for each address pool. For example, if the starting address for the eth1 pool is 1080::10:0:0:A31:1, 1080::10 (1080:0:0:10) cannot be used in the first four fields for addresses in any other pool, and the 7th and 8th fields must be configured so that none of the addresses in one pool share these values with an address in another pool.