Planet Networking & Communication CS-2001 User Manual page 87


IPv6 address represent itself as text string using the following three conventional
forms:
 Colon-hexadecimal form: This is the preferred form n:n:n:n:n:n:n:n. Each
n represents the hexadecimal value of one of the eight 16-bit elements of the
address. For example: 21DA:00D3:0000:2F3B:02AA:00FF:FE28:9C5A
 Compressed form: This is to simplify writing addresses that contains a
long string of zeros, use the compressed form, in which a single contiguous
sequence of 0 blocks are represented by a double-colon symbol (::). This
symbol can appear only once in an address. For example, the unicast
address FE80:0:0:0:2AA: FF: FE9A:4CA2 in compressed form is FE80::
2AA:FF:FE9A:4CA2.
 Mixed form:

IPv4-compatible addresses: The IPv4-compatible address,
0:0:0:0:0:0:w.x.y.z or ::w.x.y.z (where w.x.y.z is the dotted decimal
representation of a public IPv4 address), is used by IPv6/IPv4 nodes
that are communicating with IPv6 over an IPv4 infrastructure. When
the IPv4-compatible address is used as an IPv6 destination, the IPv6
traffic is automatically encapsulated with an IPv4 header and sent to
the destination using the IPv4 infrastructure.

IPv4-mapped addresses: The IPv4-mapped address,
0:0:0:0:0:FFFF:w.x.y.z or ::FFFF:w.x.y.z, is used to represent an
IPv4-only node to an IPv6 node, for example, ::ffff:192.0.2.128 is the
IPv4-mapped IPv6 address for IPv4 address 192.0.2.128

The leading bits in the address define the specific IPv6 address type. The
variable-length field containing these leading bits is called a Format Prefix (FP).
An IPv6 unicast address is divided into two parts. The first part contains the
address prefix (also known as subnet prefix such as 21DA:D3:0:2F3B::/64), and
the second part contains the interface identifier (MAC address).
 A concise way to express an IPv6 address/prefix combination is as follows:
ipv6-address/prefix-length. For example, an IPv6 address with a 64-bit
prefix is represented as 3FFE:FFFF:0:CD30:0:0:0:0/64 or
3FFE:FFFF:0:CD30::/64.
86
.