When standby WLAN-GW transitions to an active state and receives data on the anchor ISA there is not a UE state on the anchor ISA. Data-triggered authentication Data-triggered subscriber creation is used to create the subscriber. To infer how the UE originally obtained the IP@ (DHCP relay versus proxy, such as AAA or GTP), the following holds:
If any GTP related parameters are returned in access-accept, then it is assumed the IP@ comes from GGSN/PGW, and the origin for the IP@ is assumed to be GTP.
If no GTP parameter is returned, and access-accept contains framed-IP, then proxy case is assumed (that is, the origin as AAA).
If no GTP parameter or framed-IP is returned, then DHCP relay is assumed. The remaining lease time is set to initial lease-time (if it was originally provided from AAA on primary WLAN-GW, it could be provided in access-accept for data-triggered auth on backup WLAN-GW). If AAA does not provide it, then it is initialized to default value of 7 days.
If authentication indicates GTP for the subscriber, then create-session-request is signaled with Handover indication. However, for dual-sack subscriber over soft-GRE, if AAA returns the SLAAC prefix in access-accept (in response to IPv4 data-triggered auth), and linking is configured, RA message is sent (unicast to client’s MAC@), and a SLAAC host is created.