The use of a 6to4 tunnel is feasible when
- Your device is IPv6 capable and you want to access IPv6 services,
- Your provider does not support a native IPv6 network and
- You do not have access to a so-called tunnel broker who can mediate your IPv6 packets.
When using a 6to4 tunnel, the lack of support of IPv6 by the provider means the device does not receive an IPv6 address or an IPv6 prefix.
The device calculates its own unique prefix from "2002::/16" and the hexadecimal representation of its own public IPv4 address from the provider. This application only works if the device has a public IPv4 address. The device does not receive a public IPv4 address but an IPv4 address from a private address range only, for example when it accesses the Internet via UMTS and the provider supplies an IP address from its private address range, or if the device does not access the Internet directly, but is "behind" another router.
Anmerkung: Connections through a 6to4 tunnel work with relays that are selected by the IPv4 Internet provider's backbone. The device administrator has no influence on relay selection. Furthermore, the relay used can change without the administrator knowing about it. For this reason, connections via a 6to4 tunnels are suitable for test purposes only. In particular, avoid using 6to4-tunnel data connections for productive systems or for the transmission of confidential data.