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5. Automatic address configuration: To simplify the host configuration, IPv6 supports stateful
and stateless address configuration.
Stateful address configuration means that a host acquires an IPv6 address and related
information from a server (for example, DHCP server).
Stateless address configuration means that a host automatically configures an IPv6
address and related information on basis of its own link-layer address and the prefix
information advertised by a router.
In addition, a host can generate a link-local address on basis of its own link-layer address and
the default prefix (FE80::/64) to communicate with other hosts on the link.
6. Enhanced neighbor discovery mechanism: The IPv6 neighbor discovery protocol is a
group of Internet control message protocol version 6 (ICMPv6) messages that manages the
information exchange between neighbor nodes on the same link. The group of ICMPv6
messages takes the place of Address Resolution Protocol (ARP) message, Internet Control
Message Protocol version 4 (ICMPv4) router discovery message, and ICMPv4 redirection
message to provide a series of other functions.
Introduction to IPv6 address
1. IPv6 address format
An IPv6 address is represented as a series of 16-bit hexadecimals, separated by colons (:).
An IPv6 address is divided into eight groups, and the 16 bits of each group are represented by
four hexadecimal numbers which are separated by colons, for example,
2001:0d02:0000:0000:0014: 0000:0000:0095. The hexadecimal letters in IPv6 addresses are
not case-sensitive.
To simplify the representation of IPv6 addresses, zeros in IPv6 addresses can be handled as
follows:
Leading zeros in each group can be removed. For example, the above-mentioned address
can be represented in shorter format as 2001:d02:0:0:14:0:0:95.
Two colons (::) may be used to compress successive hexadecimal fields of zeros at the
beginning, middle, or end of an IPv6 address. For example, the above-mentioned address
can be represented in the shortest format as 2001:d02::14:0:0:95.
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.
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