4in6 is an IPv6 transition mechanism for the transmission of data packets over an IPv4 - IPv6 network.
At 4in6 the IPv4 traffic is packed into IPv6 data packets to enable IPv4 nodes to establish a tunnel through an IPv6 network. By this made encapsulation of IPv4 packets in IPv6 packets, it is possible that IPv4 nodes that do not support IPv6, yet able to communicate over an IPv6 network. From the perspective of IPv4 nodes to IPv6 infrastructure is used as the link layer (data link layer in the OSI model ).
4in6 tunnel can be configured manually or automatically with the use of other protocols such as TSP.