After a UE has successfully been authenticated and authorised by the 3GPP AAA Server to make use of a given non-3GPP access (over SWa/STa), ePDG (over SWm) or PDN-GW (over S6b for S2c), the 3GPP AAA Server registers its address to the HSS, unless already done. In turn, the HSS should store the address of the registered 3GPP AAA server for the given user and mark the user as registered in the 3GPP AAA Server. In the response, the HSS returns user profile data.
Step 1.
Once the UE has been successfully authenticated by the 3GPP AAA server, the 3GPP AAA Server sends a UE Registration Request (User Identity, Mobile Equipment Identity, 3GPP AAA Server address) to the HSS.
Step 2.
The HSS checks that the user is known and that the stored 3GPP AAA Server address is the same one stored for the user and that it is the same 3GPP AAA Server that previously requested authentication vectors for this same user. If this is successful, the HSS marks the 3GPP AAA Server as the registered 3GPP AAA Server for user. The HSS responds with a UE Registration Ack (User Identity, Subscription Data). The subscription data includes information to be used by the PDN GW selection function or an already selected PDN GW identity and APN if present. The subscription data shall also include an indication of MPS subscription, if the user has an MPS subscription.
The 3GPP AAA Server requests the HSS to De-Register the currently registered UE. In doing so, the 3GPP AAA Server is notifying the HSS that the UE no longer has any context in the 3GPP AAA Server. The HSS should in turn delete the registered 3GPP AAA Server address.
Step 1.
The 3GPP AAA Server sends a UE De-Registration Request (User Identity, Cause) to the HSS. The "Cause" field may take values such as Authentication-Failure, UE-Detached, Charging-System-Request, etc.
Step 2.
The HSS marks the UE as not-registered, removes the 3GPP AAA Server address previously stored for the UE and responds with a UE De-Registration Ack.
The HSS requests the 3GPP AAA Server to de-register a UE, for instance, when a subscription is withdrawn or other operator determined reasons. The 3GPP AAA Server should purge user data, set the user to not-registered and detach the UE and/or deactivate any network resources allocated to the user.
Step 1.
The HSS server sends a UE De-Registration Request (User Identity, Cause) to the 3GPP AAA Server. The "Cause" field may take values such as Subscription Withdrawn, Administrative-Reason, etc.
Step 2.
The 3GPP AAA Server marks the user as not-registered and purges any user data. It responds with a UE De-Registration Ack. In addition, the 3GPP AAA Server should initiate detach of the UE or de-activation of any network resources.
For non-emergency services, the 3GPP AAA Server updates the HSS with the PDN-GW identity of the selected PDN-GW and the APN associated with the UE's PDN Connection. For emergency services, the 3GPP AAA server may update the HSS with the PDN-GW currently in use for emergency services. This procedure only occurs when the 3GPP AAA Server has in turn successfully received the PDN-GW identity and APN (or the PDN-GW currently in use for emergency services in case of emergency services) from the PDN-GW the UE is attached to. The 3GPP AAA server should subsequently always update the HSS with the PDN-GW identity in the above-mentioned manner. This procedure is used for PDN-GW registration.
Step 1.
The 3GPP AAA Server sends a Update PDN-GW Identity Request (PDN-GW Identity, APN, User Identity) or a Update PDN-GW Identity Request (PDN-GW currently in use for emergency services) to the HSS.
The PDN-GW identity (or the PDN-GW currently in use for emergency services) is either the IP address (e.g. if the PDN-GW has a single IP address for all the mobility protocols it supports or if it only supports one mobility protocol) or the FQDN (e.g. if the PDN-GW has multiple IP addresses for the mobility protocols it supports).
Step 2.
The HSS checks that the user is known and that the stored 3GPP AAA Server name is the currently registered 3GPP AAA server for this same user. If this is successful, the HSS returns a Update PDN-GW Identity Acknowledgement.
Step 3.
Steps 3-4 are only performed if the PDN-GW identity (or the PDN-GW currently in use for emergency services) information was successfully modified in the HSS and an SGSN or MME is registered in the HSS for the same UE. In this case the HSS sends an Insert Subscriber Data message to the SGSN or MME to update the change in the SGSN or MME. If both an SGSN and an MME is registered in the HSS, and Insert Subscriber Data message is sent to each of them.
Step 4.
The SGSN or MME acknowledges by sending an Insert Subscriber Data Ack message.
In case of initial attach, or UE requested PDN connectivity in the 3GPP access, if the Request Type of the UE requested connectivity procedure does not indicate
"Emergency", the SGSN/MME updates the HSS with the PDN-GW identity of the selected PDN-GW and the APN associated with the UE's PDN connection. If a 3GPP AAA Server is registered in the HSS for the same UE, the HSS provides the updated APN and PDN-GW identity information to the 3GPP AAA Server.
If, in the case of initial attach or UE requested PDN connectivity in the 3GPP access, the Request Type of the UE requested connectivity procedure indicates
"Emergency", the SGSN/MME may update the HSS with the
"PDN-GW currently in use for emergency services". If a 3GPP AAA Server is registered in the HSS for the same UE, the HSS provides the
"PDN-GW currently in use for emergency services" to the 3GPP AAA Server.
If NBM is used for establishing connectivity in the non-3GPP access, the 3GPP AAA Server notifies the changes to the non-3GPP access network. This procedure is used for PDN-GW registration.
Step 1.
The SGSN/MME sends a Notify Request (PDN-GW Identity, APN, User Identity) or a Notify Request (PDN-GW currently in use for emergency services, User Identity) to the HSS.
Step 2.
The HSS checks that the user is known and that the stored SGSN/MME is the currently registered SGSN/MME for this same user. If this is successful, the HSS returns a Notify Response.
Step 3.
Steps 3-4 are only performed if the PDN-GW identity (or the PDN-GW currently in use for emergency services) information was successfully modified in the HSS and a 3GPP AAA Server is registered in the HSS for the same UE. In this case the HSS sends Update APN and PDN-GW Identity Request message to the 3GPP AAA Server.
Step 4.
The 3GPP AAA Server acknowledges by sending a Update APN and PDN-GW Identity Ack message.
Step 5.
If NBM is used for establishing connectivity in the non-3GPP IP access, the 3GPP AAA Server updates the ePDG/trusted non-3GPP IP access network with the new APN and PGW Identity data by sending Update APN and PDN-GW Identity message.
Step 6.
The ePDG/trusted non-3GPP IP access network acknowledges by sending Update APN and PDN-GW Identity Ack message.