IPv6 increases the number of network address
bits from 32 (IPv4) to 128 bits, which provides more unique IP addresses to support more
network devices.
An IPv6 address consists of 8 fields of 16-bit
hexadecimal values separated by colons (:).
IPv6 address format
As shown in the figure, HHHH is a 16-bit
hexadecimal value. H is a 4-bit hexadecimal value. The following is an example of an
IPv6 address: 2001:0000:0000:0200:002D:D0FF:FE48:4672.
An IPv6 address can include hexadecimal fields
of zeros. To make the address manageable, you can:
Omit the leading zeros. For example,
2001:0:0:200:2D:D0FF:FE48:4672.
Compress the successive groups of zeros at the
beginning, middle, or end of an IPv6 address to two colons (::) once per address.
For example, 2001::200:2D:D0FF:FE48:4672.
When specifying an IPv6 address in a command
syntax, consider the following:
You can use the two colons (::) only once in
the address to represent the longest successive hexadecimal fields of zeros.
The hexadecimal letters in IPv6 addresses are not case-sensitive.
As shown in the figure, the IPv6 network prefix
consists of the left-most bits of the address. As with an IPv4 address, you can specify
the IPv6 prefix using the prefix/prefix-length format, for which the following rules
apply.
The prefix parameter is specified as 16-bit hexadecimal values separated by a
colon.
The prefix-length parameter is specified as a decimal value that indicates the
network portion of the IPV6 address.
The following is an example of an IPv6 prefix:
2001:DB8:49EA:D088::/64.
