As per the above case, a router should be deployed with tunnelled uplink/external connectivity.

The decision then is how to connect the sparsely deployed hosts. Where VLANs are available, they could be used to distribute IPv6 by Layer 2 segregation to specific physical ports on the network edge. An alternative is to use ISATAP as an automatic tunnelling solution, or an internal tunnel broker. The tunnel broker and VLAN solutions are more manageable, e.g. the broker can include authentication, and thus may be preferred where a more controlled deployment is desirable.