1-2
Figure 1-1 Comparison between IPv4 header format and IPv6 header format
Adequate address space
The source IPv6 address and the destination IPv6 address are both 128 bits (16 bytes) long. IPv6 can
provide 3.4 x 1038 addresses to completely meet the requirements of hierarchical address division as
well as allocation of public and private addresses.
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.
z Stateful address configuration means that a host acquires an IPv6 address and related information
from the server (for example, DHCP server).
z 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.