H3C Technologies H3C S10500 Series Switches - Manual (Page 112)

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Hierarchical address structure
IPv6 uses hierarchical address structure to speed up route lookups and reduce the IPv6 routing table size
through route aggregation.
Address autoconfiguration
To simplify host configuration, IPv6 supports stateful and stateless address autoconfiguration.
• Stateful address autoconfiguration enables a host to acquire an IPv6 address and other
configuration information from a server (for example, a DHCP server).
• Stateless address autoconfiguration enables a host to automatically generate an IPv6 address and
other configuration information by using its link-layer address and the prefix information advertised
by a router.
To communicate with other hosts on the same link, a host automatically generates a link-local address
based on its link-layer address and the link-local address prefix (FE80::/10).
Built-in security
IPv6 defines extension headers to support IPsec. IPsec provides end-to-end security for network security
solutions and enhances interoperability among different IPv6 applications.
QoS support
The Flow Label field in the IPv6 header allows the device to label the packets and facilitates the special
handling of a flow.
Enhanced neighbor discovery mechanism
The IPv6 neighbor discovery protocol is implemented through a group of Internet Control Message
Protocol version 6 (ICMPv6) messages to manage the information exchange among neighboring nodes
on the same link. The group of ICMPv6 messages replaces Address Resolution Protocol (ARP) messages,
Internet Control Message Protocol version 4 (ICMPv4) Router Discovery messages, and ICMPv4 Redirect
messages and provides a series of other functions.
Flexible extension headers
IPv6 eliminates the Options field in the header and introduces optional extension headers to provide
scalability and improve efficiency. The Options field in the IPv4 packet header contains a maximum of
40 bytes, whereas the IPv6 extension headers are restricted to the maximum size of IPv6 packets only.
IPv6 addresses
IPv6 address format
An IPv6 address is represented as a set of 16-bit hexadecimals separated by colons. An IPv6 address is
divided into eight groups, and each 16-bit group is represented by four hexadecimal numbers, for
example, 2001:0000:130F:0000:0000:09C0:876A:130B.
To simplify the representation of IPv6 addresses, you can handle zeros in IPv6 addresses by using the
following methods.
• The leading zeros in each group can be removed. For example, the previous address can be
represented in a shorter format as 2001:0:130F:0:0:9C0:876A:130B.
• If an IPv6 address contains two or more consecutive groups of zeros, they can be replaced by a
double colon (::). For example, the previous address can be represented in the shortest format as
2001:0:130F::9C0:876A:130B.