Figure 1 shows how to enable communication between IPv6 nodes or networks in an IPv4 environment:

Figure 1. Communicating between IPv6 nodes or networks in an IPv4 environment

Tunneling provides a way to use an existing IPv4 routing infrastructure to carry IPv6 traffic. IPv6 nodes (or networks) that are separated by IPv4 infrastructure can build a virtual link by configuring a tunnel. IPv6-over-IPv4 tunnels are modeled as single-hop. In other words, the IPv6 hop limit is decremented by 1 when an IPv6 packet traverses the tunnel. The single-hop model serves to hide the existence of a tunnel. The tunnel is opaque to the network and is not detectable by network diagnostic tools such as traceroute.

z/OS® Communications Server does not support being a tunnel endpoint. This means that the z/OS Communications Server stack must have an IPv6 interface connected to an IPv6 capable router. The router is relied on to handle all tunneling issues.

For more information, see Tunneling.