AF Session Establishment (AF initiated)
1. The AF receives an internal or external trigger to set-up a new AF session and provides Service Information. The AF identifies the Service Information needed (e.g. IP address of the IP flow (s), port numbers to be used, information on media types, etc).
2. The AF provides the Service Information to the PCRF by sending a Diameter AAR for a new Rx Diameter session. If this AF session is associated with a sponsor, Sponsor-Identity AVP and the Application-Service-Provider-Identity AVP are included in Sponsored-Connectivity-Data AVP. If usage thresholds are to be associated with this sponsored AF session, then Granted-Service-Unit AVP is included in Sponsored-Connectivity-Data AVP.
3. The PCRF stores the received Service Information.
4. If the PCRF requires subscription related information and does not have it, the PCRF sends a request to the SPR in order to receive the information.
5. The SPR replies with the subscription related information containing the information about the allowed service(s), QoS information and PCC Rules information
6. If the AF session is associated with a sponsor, The PCRF identifies the affected established IP-CAN Session(s) using the information previously received from the PCEF and the Service Information received from the AF.
7. The PCRF sends a Diameter AAA to the AF. The PCRF indicates whether the support for UE IP address/mask in the TFT filter is available in the IP-CAN session.
8. The PCRF interacts with the PCEF for PCRF-Initiated IP-CAN Session Modification via RAR/RAA.
AF Session Establishment (AF initiated)
1. The AF receives an internal or external trigger to modify an existing AF session and provide related Service Information.
2. The AF identifies the Service Information needed (e.g. IP address of the IP flow(s), port numbers to be used, information on media types, etc.).
3. The AF provides the Service Information to the PCRF by sending a Diameter AAR for the existing Rx Diameter session corresponding to the modified AF session. If this AF session is associated with a sponsor, Sponsor-Identity AVP and Application-Service-Provider-Identity are included in Sponsored-Connectivity-Data AVP. If application usage thresholds are to be associated with this sponsored AF session, then Granted-Service-Unit AVP is included in Sponsored-Connectivity-Data AVP.
4. The PCRF stores the received Service Information.
5. The PCRF identifies the affected established IP-CAN Session(s) using the information previously received from the PCEF and the Service Information received from the AF.
6. The PCRF sends a Diameter AAA to the AF.
7. The PCRF interacts with the PCEF via RAR/RAA.
AF Session Termination (AF initiated)
1. The AF receives an internal or external trigger for a session release.
2. The AF sends a session termination request, Diameter STR, to the PCRF to request the removal of the session. The AF can request access network information within the STR by adding a Required-Access-Info AVP.
3. The PCRF identifies the affected IP-CAN Session where PCC Rules and, if available, QoS Rules for the IP flow(s) of this AF session are installed. These PCC/QoS Rules need to be removed.
If the AF did not request access network information, and if no usage thresholds due to an AF session associated with a sponsor were provided that relate to the installed PCC rules, step 4a applies. Otherwise step 4b applies.
4a. The PCRF sends Diameter STA, session termination answer, to the AF.
4b. The PCRF sends Diameter STA, session termination answer, to the AF and includes access network information obtained in steps 5,6,7.
5. The PCRF interacts with the PCEF via RAR/RAA.
PCEF Initiated IP-CAN Session Modification
1. The PCEF may receive a request for IP‑CAN Session modification. The IP-CAN session modification can be initiated upon receiving UE-initiated resource modification request, a new IP-CAN bearer establishment signalling , due to a specific event (e.g. UE requested PDN connectivity in all cases) or an internal trigger.
2. The PCEF informs the PCRF about the IP-CAN session modification for non-roaming case and Home Routed roaming scenario. The PCEF sends a CCR command to the PCRF including the CC-Request-Type AVP set to the value “UPDATE_REQUEST”. For an IP-CAN Session modification where an existing IP-CAN bearer is modified, the PCEF supplies the specific event that caused the IP-CAN Session modification within the Event-Trigger AVP and the PCC rule name(s) and their status within the Charging-Rule-Report AVP.
3-4. If the AF requested a notification of the corresponding event, the PCRF sends a Diameter RAR with the Specific-Action AVP set to indicate the event that caused the request. If the session modification affected a sponsored data flow and the PCRF detects that the usage threshold provided by the AF has been reached, this message includes the accumulated usage in the Used-Service-Unit AVP within the Sponsored-Connectivity-Data AVP and the Specific-Action AVP set to the value USAGE_REPORT.
5-6. If step 6 takes place, the AF may take the application specific procedure (e.g. for IMS refer to 3GPP TS 23.228[x], replies with a Diameter RAA and may provide updated service information within.
7-8. The PCRF selects or generates PCC Rule(s) to be installed. The PCRF may also identify existing PCC rules that need to be modified or removed. For the non-roaming case, and for the case when the UE is roaming in a Home Routed scenario, the PCRF provisions the PCC Rules to the PCEF using CCA command.
PCEF Initiated IP-CAN Termination
1. The PCEF detects that the termination of an IP-CAN Session or bearer is required.
2. The PCEF sends a CCR to the PCRF, indicating the IP-CAN Session termination. The PCEF requests the termination of the Gx session using the CC-Request-Type AVP set to the value TERMINATION_REQUEST. If the usage monitoring is enabled, the PCEF informs the PCRF about the resources that have been consumed by the user since the last report. If the Required-Access-Info AVP is included in any PCC Rule, the PCEF informs the PCRF about the access network information.
3. The PCRF identifies the AF sessions that are bound to IP flows of the removed IP-CAN Session.
4. The PCRF acknowledges the Gx session termination by sending a CCA to the PCEF.
5. The PCRF indicates the session abort to the AF by sending an ASR to the AF.
6. The AF responds by sending an ASA to the PCRF.
7. The AF sends an STR to the PCRF to indicate that the session has been terminated.
8. The PCRF responds by sending an STA to the AF. If the provided PCC rules are related to an AF session associated with a sponsor, usage thresholds were provided by the AF earlier, and the PCRF has usage data that has not yet been reported to the AF, the PCRF informs the AF about the resources that have been consumed by the user since the last report. If the AF requested the PCRF to report access network information in step 7, the PCRF informs the AF about the access network information.
