HP VPN Firewall Appliances Network Management Configuration Guide

676
IMPORTANT:
A
double colon can appear once or not at all in an IPv6 address. This limit allows the device to
determine how many zeros the double colon represents, and correctly convert it to zeros to restore a
128-bit IPv6 address.
An IPv6 address consists of 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 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 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 (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.
There are no broadcast addresses in IPv6. Their function is replaced by multicast addresses.
• 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.
The type of an IPv6 address is designated by the first several bits, called the format prefix. Table 77 lists
the mappings between address types and f
ormat prefixes.
Table 74 Mappings between address types and format prefixes
T
yp
e Format
p
refix (binar
y
) IPv6
p
refix 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.