Novell LINUX ENTERPRISE SERVER 10 SP2 - INSTALLATION AND ADMINISTRATION Installation Manual page 578

site-local
As a completely new feature introduced with IPv6, each network interface normally
gets several IP addresses, with the advantage that several networks can be accessed
through the same interface. One of these networks can be configured completely auto-
matically using the MAC and a known prefix with the result that all hosts on the local
network can be reached as soon as IPv6 is enabled (using the link-local address). With
the MAC forming part of it, any IP address used in the world is unique. The only variable
parts of the address are those specifying the site topology and the public topology, de-
pending on the actual network in which the host is currently operating.
For a host to go back and forth between different networks, it needs at least two address-
es. One of them, the home address, not only contains the interface ID but also an iden-
tifier of the home network to which it normally belongs (and the corresponding prefix).
The home address is a static address and, as such, it does not normally change. Still,
all packets destined to the mobile host can be delivered to it, regardless of whether it
operates in the home network or somewhere outside. This is made possible by the
completely new features introduced with IPv6, such as stateless autoconfiguration and
neighbor discovery. In addition to its home address, a mobile host gets one or more
additional addresses that belong to the foreign networks where it is roaming. These are
called care-of addresses. The home network has a facility that forwards any packets
destined to the host when it is roaming outside. In an IPv6 environment, this task is
performed by the home agent, which takes all packets destined to the home address and
relays them through a tunnel. On the other hand, those packets destined to the care-of
address are directly transferred to the mobile host without any special detours.
560 Installation and Administration
and the interface ID of the network card, with the middle part consisting of
zero bytes. Addresses of this type are used during automatic configuration to
communicate with other hosts belonging to the same subnetwork.
Packets with this type of address may be routed to other subnetworks, but not
to the wider Internet—they must remain inside the organization's own network.
Such addresses are used for intranets and are an equivalent of the private address
space defined by IPv4. They contain a special prefix (fec0::/10), the inter-
face ID, and a 16 bit field specifying the subnetwork ID. Again, the rest is
filled with zero bytes.