Section: 4.4.8 PDN GW's associated AAA Server
Content: The PDN Gateway may interact with a AAA server over the SGi interface. This AAA Server may maintain information associated with UE access to the EPC and provide authorization and other network services. This AAA Server could be a RADIUS or Diameter Server in an external PDN network, as defined in TS 29.061[ Interworking between the Public Land Mobile Network (PLMN) supporting packet based services and Packet Data Networks (PDN) ]  [38]. This AAA Server is logically separate from the HSS and the 3GPP AAA Server.