Section: 11.2.1.2.2 EPC based IPv4 Non Transparent access
Content: In this case: - a static or a dynamic IPv4 address belonging to the Intranet/ISP addressing space is allocated to a UE at IP-CAN session establishment. The methods of allocating IP address to the UE are specified in 3GPP TS 23.060[ General Packet Radio Service (GPRS); Service description; Stage 2 ]  [3], 3GPP TS 23.401[ General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access ]  [77] and 3GPP TS 23.402[ Architecture enhancements for non-3GPP accesses ]  [78]. The allocated IPv4 address is used for packet forwarding within the P-GW and for packet forwarding on the Intranet/ISP; - as a part of the IP-CAN session establishment, the P-GW may request user authentication from an external AAA server (i.e. RADIUS, Diameter) belonging to the Intranet/ISP; - the IPv4 address allocation to the UE may be performed based on the subscription or a local address pool, which belongs to the Intranet/ISP addressing space, provisioned in the P-GW. The IPv4 address allocation to the UE may also be done via the address allocation servers (i.e. DHCPv4, RADIUS AAA, Diameter AAA) belonging to the Intranet/ISP; - if requested by the UE at IP-CAN session establishment, the P-GW may retrieve the Protocol Configuration Options or IPv4 configuration parameters from a locally provisioned database in P-GW and/or from some external server (i.e. DHCPv4, RADIUS AAA, Diameter AAA) belonging to the Intranet/ISP; - the communication between the Packet Domain and the Intranet/ISP may be performed over any network, even an insecure network ,e.g. the Internet. In case of an insecure connection between the P-GW and the Intranet/ISP, there may be a specific security protocol in between. This security protocol is defined by mutual agreement between PLMN operator and Intranet/ISP administrator. Table 0 summarizes the IPv4 address allocation and parameter configuration use cases between the UE and the P-GW that may lead the P-GW to interwork with the external DHCPv4, RADIUS AAA and Diameter AAA servers over Sgi reference point. For detailed description of the signalling flows between the UE and the P-GW, see the references in the table. The detailed description of the signalling use cases that may be triggered between the P-GW and the external servers are specified in this document, as referenced in the table. Table 0 : IPv4 address allocation and parameter configuration use cases