3Com 4210 PWR Configuration Manual page 528

526 C 46: IP 6 M
HAPTER V
Introduction to IPv6
Address
C
ANGEMENT ONFIGURATION
Hierarchical address structure
IPv6 adopts the hierarchical address structure to quicken route search and reduce
the system source occupied by the IPv6 routing table by means of route
aggregation.
Automatic address configuration
To simplify the host configuration, IPv6 supports stateful address configuration
and stateless address configuration.
Stateful address configuration means that a host acquires an IPv6 address and
■
related information from the server (for example, DHCP server).
Stateless address configuration means that the host automatically configures
■
an IPv6 address and related information based on its own link-layer address
and the prefix information issued by the router.
In addition, a host can automatically generate a link-local address based on its
own link-layer address and the default prefix (FE80::/64) to communicate with
other hosts on the link.
Built-in security
IPv6 uses IPSec as its standard extension header to provide end-to-end security.
This feature provides a standard for network security solutions and improves the
interoperability between different IPv6 applications.
Support for QoS
The Flow Label field in the IPv6 header allows the device to label packets in a flow
and provide special handling for these packets.
Enhanced neighbor discovery mechanism
The IPv6 neighbor discovery protocol is implemented by a group of Internet
control message protocol version 6 (ICMPv6) messages. The IPv6 neighbor
discovery protocol manages message exchange between neighbor nodes (nodes
on the same link). The group of ICMPv6 messages takes the place of address
resolution protocol (ARP), Internet control message protocol version 4 (ICMPv4),
and ICMPv4 redirect messages to provide a series of other functions.
Flexible extension headers
IPv6 cancels the Options field in IPv4 packets but introduces multiple extension
headers. In this way, IPv6 enhances the flexibility greatly to provide scalability for IP
while improving the processing efficiency. The Options field in IPv4 packets
contains only 40 bytes, while the size of IPv6 extension headers is restricted by that
of IPv6 packets.
IPv6 addresses
An IPv6 address is represented as a series of 16-bit hexadecimals, separated by
colons. An IPv6 address is divided into eight groups, 16 bits of each group are
represented by four hexadecimal numbers which are separated by colons, for
example, 2001:0000:130F:0000:0000:09C0:876A:130B.
To simplify the representation of IPv6 addresses, zeros in IPv6 addresses can be
handled as follows: