R21xx-HP FlexFabric 11900 Layer 3 IP Services Configuration Guide

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• If an IPv6 address contains two or more consecutive groups of zeros, they can be replaced by a
double colon (::). For example, the above address can be represented in the shortest format as
2001:0:130F::9C0:876A:130B.
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.
An IPv6 address prefix is written in IPv6-address/prefix-length notation, where 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 interface among the interfaces
identified by that address. The nearest interface is chosen according to the routing protocol'
measure of distance.
The type of an IPv6 address is designated by the first several bits, called the format prefix. Table 6 list
s
the mappings between address types and format prefixes.
Table 6 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
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.