Which approach can you use to implement IPv6-over-IPv4 tunneling?

The correct approach for implementing IPv6-over-IPv4 tunneling is through the use of IPsec. IPsec allows for the encapsulation of IPv6 packets within IPv4 packets, providing a secure method for transmitting data over an IPv4 infrastructure. This tunneling method preserves the integrity and confidentiality of the IPv6 traffic, making it ideal for secure communications.

Other approaches have notable characteristics, but they do not directly facilitate the tunneling of IPv6 packets over an IPv4 network as efficiently or securely as IPsec. For instance, IPv4-compatible addressing mainly refers to a method of addressing that allows IPv6 nodes to communicate with IPv4 nodes but does not inherently provide tunneling capabilities. Dual-stack implementations enable devices to handle both IPv4 and IPv6 natively without encapsulating packets, thus not addressing the specific requirement for tunneling. Finally, 6PE (IPv6 Provider Edge) is a method used for enabling IPv6 traffic across an MPLS network but is more specialized and does not focus on direct tunneling in an IPsec context.