Configured tunneling refers to IPv6 over IPv4 tunneling, where the IPv4 tunnel endpoint address is determined by configuration information for the encapsulating node. The tunnels can be unidirectional or bidirectional. Bidirectional configured tunnels act similarly as virtual point-to-point links. For each tunnel, the encapsulating node must store the tunnel endpoint address. When an IPv6 packet is transmitted over a tunnel, the tunnel endpoint address configured for that tunnel is used as the destination address for the encapsulating IPv4 header.

Routing information for the encapsulating node usually determines which packets to tunnel. This is typically done by way of a routing table, which directs packets based on their destination address using the prefix mask and match technique.

Configured tunnels can be host-host, host-router, or router-router. Host-host tunnels allow two IPv6/IPv4 nodes to send IPv6 packets directly to one another without going through an intermediate IPv6 router. This can be useful if the applications need to take advantage of IPv6 features that are not available in IPv4.

An IPv6/IPv4 host that is connected to datalinks with no IPv6 routers can use a configured tunnel to reach an IPv6 router. This tunnel allows the host to communicate with the rest of the IPv6 Internet. If the IPv4 address of an IPv6/IPv4 router bordering the IPv6 backbone is known, this can be used as the tunnel endpoint address, and can be used as an IPv6 default route. This default route is used only if a more specific route is not known.

Configured tunnels can also be used between routers, allowing isolated IPv6 networks to be connected by way of an IPv4 backbone. This connectivity can be accomplished by arranging tunnels directly with each IPv6 site to which connectivity is needed, but more typically it is done by arranging a tunnel into a larger IPv6 routing infrastructure that can guarantee connectivity to all IPv6 user site networks. One example of this type of IPv6 routing infrastructure is the 6bone.

When using configured tunnels, a peering relationship must be established between the two IPv6 sites. This requires establishing a technical relationship with the peer and working through the various low-level details of how to configure tunnels between the two sites, including answering questions such as what peering protocol is used (presumably, an IPv6-capable version of BGP4).