ISATAP is another automatic tunnelling mechanism based on the automatic creation of IPv6-in-IPv4 tunnels. As such – from a security point of view – it should not be used, if manually configured IPv6- in-IPv4 tunnels are an option. However, since ISATAP is specifically meant to be used only within a site and if correspondingly protected, it is a reasonably secure and low maintenance mechanism, to provide isolated dual-stack hosts with IPv6 connectivity to the site’s main IPv6 network and thereby global IPv6 connectivity.