H3C Technologies H3C S12500 Series Switches - Manual (Page 148)

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An IPv6 address consists of two parts: an address prefix and an interface ID, which are equivalent to the
network ID and the host ID of an IPv4 address respectively.
An IPv6 address prefix is written in IPv6-address/prefix-length notation where the IPv6-address is
represented in any of the formats above and the prefix-length is a decimal number indicating how many
leftmost bits of the IPv6 address are the address prefix.
IPv6 address types
IPv6 addresses include the following types:
• Unicast address—An identifier for a single interface, similar to an IPv4 unicast address. A packet
sent to a unicast address is delivered to the interface identified by that address.
• Multicast address—An identifier for a set of interfaces (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.
• Anycast address—An identifier for a set of interfaces (belonging to different nodes). A packet sent
to an anycast address is delivered to the nearest one of the interfaces identified by that address. The
nearest interface is chosen according to the routing protocols' measure of distance.
NOTE:
There are no broadcast addresses in IPv6. Their function is replaced by multicast addresses.
The type of an IPv6 address is designated by the first several bits called the format prefix. Table 7 lists the
mappings between address types and format prefixes.
Table 7 Mappings between address types and format prefixes
Type Format prefix (binary) IPv6 prefix ID
Unicast
address
Unspecified address 00...0 (128 bits) ::/128
Loopback address 00...1 (128 bits) ::1/128
Link-local address 1111111010 FE80::/10
Site-local address 1111111011 FEC0::/10
Global unicast address Other forms N/A
Multicast address 11111111 FF00::/8
Anycast address
Anycast addresses use the unicast address space and have the
identical structure of unicast addresses.
Unicast addresses
Unicast addresses include the following types:
• Global unicast addresses, equivalent to public IPv4 addresses, are provided for network service
providers. This type of address allows efficient prefix aggregation to restrict the number of global
routing entries.
• Link-local addresses are used for communication among link-local nodes for neighbor discovery
and stateless autoconfiguration. Packets with link-local source or destination addresses are not
forwarded to other links.
• Site-local unicast addresses are similar to private IPv4 addresses. Packets with site-local source or
destination addresses are not forwarded out of the local site (or a private network).