HP 6125G HP 6125G & 6125G/XG Blade Switches Layer 3 - IP Services Conf - Page 89

IPv6 address types, Unicast addresses

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An IPv6 address prefix is written in IPv6-address/prefix-length notation where the IPv6-address is represented in any of the formats previously mentioned and the prefix-length is a decimal number indicating how many leftmost bits of the IPv6 address comprises the address prefix. IPv6 address types IPv6 addresses fall into 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 (typically 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 (typically 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, the format prefix. Table 5 lists the mappings between address types and format prefixes. Table 5 Mappings between address types and format prefixes Type Format prefix (binary) IPv6 prefix ID Unspecified address 00...0 (128 bits) ::/128 Unicast address Loopback address Link-local address Site-local address 00...1 (128 bits) 1111111010 1111111011 ::1/128 FE80::/10 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 comprise global unicast addresses, link-local unicast addresses, site-local unicast addresses, the loopback address, and the unspecified address. • 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). 81

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81
An IPv6 address prefix is written in IPv6-address/prefix-length notation where the IPv6-address is
represented in any of the formats previously mentioned and the prefix-length is a decimal number
indicating how many leftmost bits of the IPv6 address comprises the address prefix.
IPv6 address types
IPv6 addresses fall into 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 (typically 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 (typically 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, the format prefix.
Table 5
lists the
mappings between address types and format prefixes.
Table 5
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 comprise global unicast addresses, link-local unicast addresses, site-local unicast
addresses, the loopback address, and the unspecified address.
•
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).