Operation Manual
across an IPv4 network. Such a connection between two IPv4 hosts is called a tunnel.
To achieve this, packets must include the IPv6 destination address (or the corresponding
prex) as well as the IPv4 address of the remote host at the receiving end of the tunnel.
A basic tunnel can be congured manually according to an agreement between the
hosts' administrators. This is also called static tunneling.
However, the conguration and maintenance of static tunnels is often too labor-intensive
to use them for daily communication needs. Therefore, IPv6 provides for three different
methods of dynamic tunneling:
6over4
IPv6 packets are automatically encapsulated as IPv4 packets and sent over an IPv4
network capable of multicasting. IPv6 is tricked into seeing the whole network
(Internet) as a huge local area network (LAN). This makes it possible to determine
the receiving end of the IPv4 tunnel automatically. However, this method does not
scale very well and is also hampered by the fact that IP multicasting is far from
widespread on the Internet. Therefore, it only provides a solution for smaller cor-
porate or institutional networks where multicasting can be enabled. The specica-
tions for this method are laid down in RFC 2529.
6to4
With this method, IPv4 addresses are automatically generated from IPv6 addresses,
enabling isolated IPv6 hosts to communicate over an IPv4 network. However, a
number of problems have been reported regarding the communication between
those isolated IPv6 hosts and the Internet. The method is described in RFC 3056.
IPv6 Tunnel Broker
This method relies on special servers that provide dedicated tunnels for IPv6 hosts.
It is described in RFC 3053.
21.2.4 Conguring IPv6
To congure IPv6, you normally do not need to make any changes on the individual
workstations. IPv6 is enabled by default. You can disable it during installation in the
network conguration step described in Section “Network Conguration” (Chapter 1,
Installation with YaST, ↑Start-Up). To disable or enable IPv6 on an installed system,
use the YaST Network Settings module. On the Global Options tab, check or uncheck
the Enable IPv6 option as necessary. To enable or disable IPv6 manually, edit /etc/
modprobe.d/50-ipv6.conf and restart the system. If you want to enable it tem-
Basic Networking 325