IPv6 addresses

The IPv6 address is a computer address that is unique in the network. The 128-bit long IPv6 address takes the form of eight colon-separated address fields each of which contains 2 bytes of the IPv6 address in hexadecimal form (“colon notation”), e.g.:

FEDC:BA98:7654:3210:FEDC:BA98:7654:3210

Leading zeros can be omitted. Thus, for example

1080:0000:0000:0000:0008:0800:200C:417A

and

1080:0:0:0:8:800:200C:417A

are equivalent.

The string “::” continues to represent a continuous series of “0000” strings.
This may occur at most once within an IPv6 address.
Thus the above example could also be represented as follows:

1080::8:800:200C:417A

Unlike IPv4, IPv6 does not support broadcast addressing. Instead, multicast addresses, which always start with X’FF‘, are used for many protocol functions (e.g. “Neighbor Discovery”).

Predefined IPv6 addresses

IPv6 address	Meaning
::1	Loopback address
::<IPv4-address>	IPv4-compatible IPv6 address (tunnelling) Only “dotted decimal notation” is permitted in order to represent the IPv4 address.
::FFFF:<IPv4-address>	IPv4-mapped IPv6 address (pure IPv4 node) Only “dotted decimal notation” is permitted in order to represent the IPv4 address.
FF02::1	“Link-Local” multicast address: all routers and end systems at a subnetwork

IPv6 address prefixes

The left-hand part of the IPv6 address consists of a variable-length IPv6 address prefix. The length of the IPv6 address prefix is represented as follows:

IPv6-address/IPv6-prefix length

Here the prefix length is specified as a number of bits in decimal form.
  

The address

12AB:0000:0000:CD30:0123:4567:89AB:CDEF

with the 60-bit IPv6 prefix

12AB00000000CD3

can therefore be represented as

12AB::CD30:123:4567:89AB:CDEF/60

Predefined IPv6 address prefixes

Prefix	Name	Comment
FE80/10	Link-Local prefix	Communication within a subnet
FEC0/10	Site-Local prefix	Communication within a range
FF02::1:FF/104	Solicited Node Multicast Address	The multicast address assigned to every IPv6 unicast address

Supported input/output formats

IPv6 addresses must be entered in “colon notation”. In the case of local IPv6 addresses, it is also necessary to specify the prefix length.
In both cases, leading zeros can be omitted.
When specifying “IPv4-compatible IPv6 addresses”, any leading zeros must be omitted and the IPv4 address must be specified in “dotted decimal notation”.

BCAM always outputs IPv6 address in “colon notation”. It also outputs local IPv6 addresses together with their prefix but suppresses leading zeros.