ofile of the mobile stored in the HSS entity. During phase (D), the mobile communicates to the PGW entity the HoA and CoA in the Binding Update message of the Mobility extension of the IPv6 header. During phase (D), the PGW entity can also initiate a session with the PCRF entity to retrieve the profile of the mobile stored in the SPR entity. The PGW terminates phase (D) by issuing the Binding Acknowledgment message of the Mobility extension of the IPv6 header. At the end of phase (D), the IP tunnel S2c is established between the mobile and the PGW entity. 9.3.2. Untrusted Wi-Fi access The establishment of the S2c tunnel constitutes one of the different phases of the mobile attachment described in Figure 9.9. Wi-Fi access server Local IP address allocation IPSec security association between mobile and ePDG entity CoA address allocation Binding Update Binding Acknowledgement Figure 9.9. S2c tunnel establishment Untrusted Wi-Fi access Wi-Fi Integration to the 4G Mobile Network Phase (A) corresponds to the authentication procedure described in Chapter 6. At the end of phase (A), the untrusted Wi-Fi access has recovered the service profile of the mobile stored in the HSS entity. Untrusted Wi-Fi access provides the mobile with a Local IP Address to start Phase (B) of the procedure. Phase (B) corresponds to the procedure for establishing the SWu tunnel described in Chapter 7. At the end of phase (B), an IPSec tunnel is established between the mobile and the ePDG entity, the ePDG entity has retrieved the service profile of the mobile stored in the HSS entity and assigned the mobile its CoA. Phase (C) is the establishment of an IPSec association between the mobile and the PGW entity to protect the DSMIPv6 control messages. At the end of phase (C), the PGW entity allocated the mobile its HoA and retrieved the mobile service profile stored in the HSS entity. During phase (D), the mobile communicates to the PGW entity the HoA and CoA in the Binding Update message of the Mobility extension of the IPv6 header. During phase (D)