(see Section 4.5) whether the subscribed PDN Type, the requested PDN Type, and the network wide configuration matches and based on that selects what goes into the PDN Type information element in the Create Session Request GTPv2-C message (which in this example is IPv4v6). The GTPv2-C messages also contain the PCO option, the selected APN (either from the UE or from the subscription profile), the Dual Address Bearer Flag (DAF) setting, and possibly static addressing information among other information. IPv6 in 3GPP Networks 4. The PGW receives the Create Session Request message and checks whether the requested PDN Connection can be established, based on the received information and what has been configured in the PGW. At this point, the PGW may also consult external AAA or DHCP servers for address allocation and/or connection authorization (see Section 4.2.4 for more information). Based on the requested PDN Type IPv4v6, the PGW has assigned an IPv4 address and an IPv6 prefix for the PDN Connection. The PGW also generates/assigns two IIDs for the UE and the PGW itself for link-local address configuration. 5. The PGW sends the Create Session Response message via the SGW to the MME. The message contains a PDN Address Allocation information element, which carries the assigned IPv6 prefix, the assigned IID for the UE, the assigned IPv4 address, and the PDN Type (IPv4v6 in this example). The message also contains the response PCO option from the PGW to the UE, which would, for example, have the DNS server information. 6. The MME initiates the PDN Connection/default bearer activation, and sends the Acti- vate Dedicated EPS Bearer Context Request message to the UE. This NAS message contains all the previously mentioned information from the GTPv2-C message with an exception that the IPv6 prefix is not sent to the UE, only the PGW assigned IID. This step is followed by an additional signaling between the UE and the MME that is not shown in Figure 4.27. 7. The UE configures its IPv4 address, DNS server information, and the r