h exactly one IPv4 address. This PDN Type is commonly referred as the IPv4-only bearer or IPv4-only PDN Connection. The PDN Type IPv4 has been part of the 3GPP specifications since the first release of 3GPP specifications [8]. PDN Type IPv6 - the PDN Connection is associated with exactly one IPv6 prefix with a /64 prefix length. This PDN Type is commonly referred as the IPv6-only bearer or IPv6- only PDN Connection. The PDN Type IPv6 has been part of the 3GPP specifications effectively since 3GPP Release-99 [8]. PDN Type IPv4v6 - the PDN Connection is associated with both an IPv4 address and an IPv6 prefix. This PDN Type is also commonly referred as a dual-stack bearer or a dual-stack PDN Connection. The PDN Type IPv4v6 has been part of the 3GPP specifications since the 3GPP Release-8 for EPS (i.e. for S5/S8-interfaces and S4- interfaces) [15, 16] and since Release-9 for GPRS (i.e. for Gn/Gp-interfaces) [8, 15] (For an unknown reason EPC and GPRS had an unfortunate feature disparity regarding PDN Type IPv4v6. The GPRS got to the same level only in 3GPP Release-9.) Only the negotiated type of traffic can be transported over the PDN Connection. Furthermore, it is a common practice to apply ingress filtering to prohibit a UE from sending IP packets with a different source addresses than that associated with the PDN Connection [17]. There are, however, mobile router solutions where a complete IPv4 subnet is statically routed to a network behind the UE. Such solutions are vendor specific and not covered by 3GPP standards. The strict separation of PDN Types and the restriction of one IPv4 address and/or IPv6 prefix per PDN Connection has caused a significant increase in the amount of concurrent PDN Connections per UE. For example, if a UE that conforms to 3GPP pre- Release-8 standards wants to have dual-stack connectivity, it basically has to create two concurrent PDN Connections: one of PDN Type IPv4 and another of PDN Type IPv6. Furthermore, when there is a need to separate traffic and provide differentiated routing 