IPv4 and IPv6 tunneling¶
This chapter describes how to configure IPv4 and IPv6 tunneling techniques.
Tunneling is a widespread technique used in networking, to resolve many problems: IPv4 / IPv6 migration, Virtual Private Networks, routing. It consists in encapsulating a layer 3 PDU (Protocol Data Unit), typically a packet, into a new layer 3 packet, by appending an IP header. Turbo IPsec provides several techniques to tunnel IP packets into new IP packets (the inner and outer IP versions may differ).
Tunneling techniques create a virtual layer 2 link (called a tunnel) between the source and destination of the encapsulating packets, and hide the network topology between these two endpoints, as if the two endpoints where directly connected. Therefore, Turbo IPsec creates a logical point-to-point interface, that appears in the list of interfaces and that can be used by other functions, notably routing.