HP Serviceguard manual IPv6 Network Support, IPv6 Address Types

H IPv6 Network Support

This appendix describes some of the characteristics of IPv6 network addresses. Topics:

•IPv6 Address Types

•Network Configuration Restrictions

•Local Primary/Standby LAN Patterns

•IPv6 Relocatable Address and Duplicate Address Detection Feature (page 381)

IPv6 Address Types

Several IPv6 types of addressing schemes are specified in the RFC 2373 (IPv6 Addressing Architecture). IPv6 addresses are 128-bit identifiers for interfaces and sets of interfaces. There are various address formats for IPv6 defined by the RFC 2373. IPv6 addresses are broadly classified as follows:

The following table explains the three types of IPv6 address types: unicast, anycast, and multicast.

Table 16 IPv6 Address Types

Unicast	An address for a single interface. A packet sent to a unicast address is delivered to the interface
	identified by that address.
Anycast	An address for a set of interfaces. In most cases these interfaces belong to different nodes. A
	packet sent to an anycast address is delivered to one of these interfaces identified by the address.
	Since the standards for using anycast addresses is still evolving, they are not supported in HP-UX
	as of now.
Multicast	An address for a set of interfaces (typically belonging to different nodes). A packet sent to a
	multicast address will be delivered to all interfaces identified by that address.

Unlike IPv4, there are no broadcast addresses in IPv6 because their functions are superseded by multicast.

Textual Representation of IPv6 Addresses

There are three conventional forms for representing IPv6 addresses as text strings:

•The first form is x:x:x:x:x:x:x:x, where x’s are the hexadecimal values of eight 16-bit pieces of the 128-bit address. Example:

2001:fecd:ba23:cd1f:dcb1:1010:9234:4088.

•Some of the IPv6 addresses may contain a long strings of zero bits. In order to make it easy for representing such addresses textually a special syntax is available. The use of “::” indicates that there are multiple groups of 16-bits of zeros. The “::” can appear only once in an address and it can be used to compress the leading, trailing, or contiguous sixteen-bit zeroes in an address. Example:

fec0:1:0:0:0:0:0:1234 can be represented as fec0:1::1234.

•When dealing with a mixed environment of IPv4 and IPv6 nodes there is an alternative form of IPv6 address that will be used. It is x:x:x:x:x:x:d.d.d.d, where 'x's are the hexadecimal values of higher order 96 bits of IPv6 address and the 'd's are the decimal values of the 32-bit lower order bits. Typically IPv4 Mapped IPv6 addresses and IPv4 Compatible IPv6 addresses will be represented in this notation. These addresses will be discussed in later sections.

Examples:

0:0:0:0:0:0:10.1.2.3 and

::10.11.3.123

378 IPv6 Network Support