ss for the client than the client used in sending the request. In this case, the client has to talk also to the inner, newly detected, NAT, in order to have the rules set correctly all the way from the client to the Internet. A specific Recursive PCP solution proposal for this scenario has been published [97]. This kind of scenario could appear, for example, if a UE is participating in a double translation scheme: a PCP client on a computer using tethering with a UE to access the Internet could first detect the outer NAT on the network, a NAT64, and then the inner NAT, a NAT46, on the UE. The client on the computer may need to create mappings to both NAT46 and NAT64 to have the full path covered. 6.4.6 Relation to IPv6 Transition Even though the main need for PCP is in the IPv4-only domain, where IPv4 address shortage is complicating deployments and perhaps some more lifetime for IPv4 can be bought with PCP, there is also clear use in IPv6: Firewall control: The need for firewalls continues to exist when the Internet moves from IPv4 to IPv6. While some 3GPP deployments may manage without firewalls, others Future of IPv6 in 3GPP Networks will use them. Hence there continues to be the need for controlling session timeouts and to allow selected incoming connections to get through. NAT64 control: The IPv6-only deployment with NAT64 is happening - see Section 5.4.3. UEs will have a need to manage NAT timeouts for IPv4-only destinations, and also for allowing incoming connections from the IPv4-only peers. IPv6 NAT control: Although IPv6-to-IPv6 NAT is a heresy, even without port translation, the world has a bad habit of going in unwanted directions. If these entities were to become a reality, port control needs would be there for IPv6 just as they are today for IPv4. Internet of Things The Internet of Things (IoT) is a topic that has been discussed for decades, often with different names but with more or less in the same context, for example: Machine-to- Machine (M2M) type of communications, smart homes, and ubiquitous