TP-Link T1700G-28TQ User Manual page 28

Note:
Two colons (::) can be used only once in an IPv6 address, usually to represent the longest
successive hexadecimal fields of zeros. If two colons are used more than once, the device is
unable to determine how many zeros double-colons represent when converting them to zeros to
restore a 128-bit IPv6 address.
An IPv6 address consists of two parts: address prefix and interface ID. The address prefix and
the interface ID are respectively equivalent to the network ID and the host ID in an IPv4
address.
An IPv6 address prefix is represented in "IPv6 address/prefix length" format, where "IPv6
address" is an IPv6 address in any of the above-mentioned formats and "prefix length" is a
decimal number indicating how many leftmost bits from the preceding IPv6 address are used
as the address prefix.
2. IPv6 address classification
IPv6 addresses fall into three types: unicast address, multicast address, and anycast address.
Unicast address: An identifier for a single interface, on a single node. A packet that is sent

to a unicast address is delivered to the interface identified by that address.
Multicast address: An identifier for a set of interfaces (typically belonging to different nodes),

similar to an IPv4 multicast address. A packet sent to a multicast address is delivered to all
interfaces identified by that address. There are no broadcast addresses in IPv6. Their
function is superseded by multicast addresses.
Anycast address: An identifier for a set of interfaces (typically belonging to different nodes).

A packet sent to an anycast address is delivered to one of the interfaces identified by that
address (the nearest one, according to the routing protocols' measure of distance).
The type of an IPv6 address is designated by the first several bits called format prefix. The
following table lists the mappings between address types and format prefixes.
Unassigned address
Loopback address
Link-local address
Unicast
address
Site-local address
Global unicast address
(currently assigned)
Reserved type
(to be assigned in future)
Type Format Prefix (binary)
00...0 (128 bits)
00...1 (128 bits)
1111111010
1111111011
001
Other formats
18
IPv6 Prefix ID
::/128
::1/128
FE80::/10
FEC0::/10
2xxx::/4 or 3xxx::/4