idered to be rather heavy- weight, and something more suitable for personal computers than for mobile phones. (At the time, personal computer operating systems only had IPv4 support. There was debate whether normal mobile phones could even support IPv6. Interestingly, these days work is ongoing to deploy Internet of Things (IoT) with coin cell battery operated IPv6 enabled smart objects, as we describe in Section 6.5.) Full Internet connectivity was considered to be much too heavy for mobile phones, and there were questions if phones could ever be connected to the Internet the same way the personal computers were. Thus, it is logical that the 3GPP engineers had a temptation to take shortcuts in the specification, and try to optimize the IP transport, and the IP stack itself to make IP more suitable for the mobile communication. When shortcuts are taken, and if protocols are strongly optimized, there is at least a risk that the optimization would have made cellular IP incompatible with wire- line IP. This might have made 3GPP networks, at least in the early stages, incompatible with the Internet. Luckily the 3GPP community had more vision than this. Perhaps the most important principle during the 3GPP IP service standardization has been strict compatibility with standard Internet Protocol. This means that the IP stacks in the UE behave in the standard way, the network expects standard behavior, and the IP packets are transported in the same way over the network as they would in any other network. This is one of the key factors that has made the 3GPP networks successful, and the Internet access service is usable for a range of devices not imaginable at the time of the standardization. Deploying IPv6 in 3GPP Networks Configuration and Address Management The IP stack, especially the IPv6 stack, has been designed to work well in an unmanaged environment. The IP stacks try to configure themselves as autonomically as possible. However, the principle of telecommunication networks, and especially mobile telecom- municatio