4.3.2 PCEF –Initiated IP-CAN Session Modification (PCC Rule Provisioning in PULL Mode)

29.2133GPPPolicy and charging control signalling flows and Quality of Service (QoS) parameter mappingRelease 17TS

4.3.2.1 PCEF-initiated IP-CAN Session Modification. AF located in HPLMN.

This flow shows the provisioning of PCC Rules and/or authorized QoS triggered by the PCEF.

Figure 4.3.2.1.1: PCEF-initiated IP-CAN Session Modification. AF in HPLMN.

1. For case 2a and 2b, the BBERF may initiate Gateway Control and QoS rules request procedure described in subclause 4.4.2.

2. 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 (case 1), a new IP-CAN bearer establishment signalling (case 1), due to a specific event (e.g. UE requested PDN connectivity in all cases) or an internal trigger(e.g. if the PCEF supports Application Detection and Control feature, the start/stop of application traffic event that matches with one or more activated PCC rules for application detection and control that do not contain the Mute-Notification AVP has been detected by the PCEF).

3. The PCEF informs the H-PCRF about the IP-CAN session modification for non-roaming case and Home Routed roaming scenario. The PCEF sends a CCR command to the H-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. For an IP-CAN Session modification where an existing IP-CAN bearer is terminated, the PCEF supplies the affected PCC rule name(s), their status set to inactive, the rule failure code and, if available, the RAN/NAS/TWAN/Untrusted WLAN cause(s) within the Charging-Rule-Report AVP. In the case where the UE initiates a resource modification request procedure, the PCEF includes the Packet-Filter-Information AVP, Packet-Filter-Operation AVP and QoS-Information AVP, if applicable. In the case of PCEF supporting Application Detection and Control feature, when the start or stop of the application’s traffic, identified by TDF-Application-Identifier, is detected, if PCRF has previously subscribed to the APPLICATION_START/APPLICATION_STOP Event-Triggers, the PCEF shall report the information regarding the detected application’s traffic in the Application-Detection-Information AVP in the CCR command. If NBIFOM applies to the IP-CAN session, if one of the conditions specified in subclause 4.5.25.2 of 3GPP TS 29.212 [9] applies, the PCEF informs the PCRF accordingly making use of the applicable event trigger, i.e. "ADDITION_OF_ACCESS", " REMOVAL_OF_ACCESS", "UNAVAILIBILITY_OF_ACCESS", "AVAILIBILITY_OF_ACCESS" or "ROUTING_RULE_CHANGE".

When the UE is roaming in a Visited Access case, steps 3a ~ 3c are executed instead of step 3:

3a. The PCEF sends a Diameter CCR to the V-PCRF to request PCC/ADD Rules for the roaming user. The parameters listed in step 3 are applicable here.

3b. The V-PCRF stores the information received in the Diameter CCR from the PCEF.

3c. The V-PCRF sends a CCR command with the CC-Request-Type AVP set to “UPDATE_REQUEST” to the H-PCRF. The V-PCRF includes the Subsession-Enforcement-Info AVP and the assigned S9 subsession identifier within Subsession-Id AVP. The Subsession-Operation AVP is set to the value “MODIFICATION”.

4. If the H-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) and PCC Rules information.

NOTE 1: For steps 4 and 5: The details associated with the Sp reference point are not specified in this Release. The SPR’s relation to existing subscriber databases is not specified in this Release.

6. If the AF requested a notification of the corresponding event, the H-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 H-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.

7. If step 6 takes place, the AF may take the application specific procedure (e.g. for IMS refer to 3GPP TS 23.228 [59], replies with a Diameter RAA and may provide updated service information within. Additionally, the AF may terminate the Rx session as per subclause 4.3.1.2.3.

8-11. If all service data flows for an AF session are deleted, the AF session is terminated. If the session modification affected a sponsored data flow and the H-PCRF detects the UE is roaming with home routed case, the H-PCRF initiates the AF session termination.

If the IP-CAN session is associated with a sponsor, usage thresholds were provided by the AF earlier, and the H-PCRF has usage data that has not yet been reported to the AF, the H-PCRF informs the AF, in step 11, about the resources that have been consumed by the user since the last report.

If RAN-NAS-Cause feature is supported and RAN/NAS/TWAN/Untrusted WLAN cause(s) and/or access network information were received in step 3, the H-PCRF sends this information to the AF in step 11.

NOTE 2: Initial/intermediate/Final Spending Limit Report Request can be triggered at any time after this if PCRF, based on policy decisions, find the need to initialize, modify, or deactivate spending limit reporting for the subscriber according to subclause 4.7.1/2/3 respectively.

12. The H-PCRF selects or generates PCC Rule(s) to be installed. The H-PCRF may also identify existing PCC rules that need to be modified or removed. In the case of VPLMN supporting Application Detection and Control feature for solicited application reporting, some of those PCC Rules may be used for application detection and control. The PCC Rules may relate to any of the matching AF sessions or may exist in the PCRF without matching to any AF session. The H-PCRF may also make a policy decision by deriving an authorized QoS and by deciding whether service data flows described in the PCC Rules are to be enabled or disabled. The H-PCRF may also update the ADC decisions and select the ADC rules to be installed, modified or removed for the IP-CAN session in the non-roaming case. If the NBIFOM applies to the IP-CAN session, the PCRF can also make a decision of NBIFOM as defined in subclause 4.5.25.2 of 3GPP TS 29.212 [9].

13. For the non-roaming case, and for the case when the UE is roaming in a Home Routed scenario, the H-PCRF provisions the PCC Rules to the PCEF using CCA command. The H-PCRF also provides the selected Bearer Control Mode, if changed and applicable for the IP-CAN type. The PCRF may also provide a new list of event triggers for which the PCRF requires to be notified. The PCRF may provide QoS information within the APN-AMBR AVP and the Default-EPS-Bearer-QoS AVP. In the case of PCEF supporting Application Detection and Control feature, the H-PCRF may provision the PCC rules for application detection and control to the PCEF.

When the UE is roaming in a Visited Access, steps 13a ~13c are executed instead of step 13:

13a. The H-PCRF sends a Diameter CCA to the V-PCRF including the PCC Rules to be provisioned within the Subsession-Decision AVP, along with the S9 subsession identifier as received in step 3b within the Subsession-Id AVP. Other parameters listed in step 9 are also applicable here.

13b. The V-PCRF validates the QoS parameters requested within the PCC Rules and enforces visited operator policies regarding QoS authorization requested by the H-PCRF as indicated by the roaming agreements. In case of TDF, the V-PCRF extracts and validates the ADC rules from the PCC rules received from the H-PCRF according to the local policy and roaming agreements if provided by the H-PCRF.

NOTE: If the V-PCRF rejects provisioned PCC rules received from the H-PCRF, the remaining steps in this call flow are not followed. Instead, the V-PCRF shall notify the H-PCRF by sending a Diameter CCR, including the Experimental-Result-Code AVP set to the value PCC_RULE_EVENT, identify the failed PCC rules as specified in 3GPP TS 29.215 [22], and additionally may provide the acceptable QoS Information for the service.

13c. The V-PCRF provisions PCC rules to the PCEF by using CCA command. The parameters listed in step 13a are applicable here.

13d. In case of TDF, solicited application reporting, the V-PCRF provisions the ADC rules to the TDF as defined in subclause 4.6.3.2. In case of TDF, unsolicited application reporting, the V-PCRF initiates the TDF session termination as defined in clause 4.6.2 if the PCEF reported the UE_IP_ADDRESS_RELEASE to the V-PCRF and there is an active Ipv4 address related TDF session for that IP-CAN session.

14. In case of TDF, solicited application reporting, the H-PCRF provisions the ADC rules to the TDF as defined in subclause 4.6.3.2. In case of TDF, unsolicited application reporting, the H-PCRF initiates the TDF session termination as defined in subclause 4.6.2 if the PCEF reported the UE_IP_ADDRESS_RELEASE to the H-PCRF and there is an active Ipv4 address related TDF session for that IP-CAN session.

15. The PCEF installs, modifies or removes the provided PCC Rules. The PCEF also enforces the authorized QoS and enables or disables service flows according to the flow status of the corresponding PCC Rules. In the case of PCEF supporting Application Detection and Control feature, the PCEF enforces application detection and control.

16. If traffic steering control over St applies, if the PCRF determines that the traffic steering control information needs to be provisioned for the IP-CAN session; the PCRF initiates the St session establishment procedure according to the subclause 4.9.2. If the PCRF determines that the traffic steering control information provisioned to the TSSF needs to be updated, the PCRF initiates the St session modification procedure according to the subclause 4.9.3. If the PCRF determines that the traffic steering control information is not needed for the IP-CAN session any more, the PCRF initiates the St session termination procedure according to the subclause 4.9.2.

17. The PCEF may initiate IP-CAN session signalling or acknowledges any IP‑CAN Session signalling for IP-CAN Session modification received in step 2.

18. If the PCRF requested to confirm that the resources associated to a PCC Rule have been successfully allocated or the resource release procedure has concluded, the PCEF-initiated IP-CAN session modification procedure is performed again starting from step 3.

19. For case 2a and 2b, the PCRF may initiate Gateway Control and QoS rules Provision procedure described in subclause 4.4.3.

4.3.2.2 PCEF-initiated IP-CAN Session Modification, AF located in the VPLMN

Figure 4.3.2.2.1: PCEF-initiated IP-CAN Session Modification, AF in VPLMN. If the AF resides in the VPLMN, the V‑PCRF proxies the AF session signalling over S9 between the V-AF and the H‑PCRF.

1. Steps 1 to 5 in figure 4.3.2.1.1 are executed.

When all PCC Rules related to a particular AF session are removed, the H-PCRF initiates the AF session termination procedure. For each AF session bound to the modified IP-CAN session that is being removed, steps 2-9 are executed instead of steps 10-13:

2. The H-PCRF indicates the session abort to the V-PCRF by sending a Diameter ASR to the V-PCRF.

3. The V-PCRF proxies the Diameter ASR command to the V-AF.

4. The V-AF responds by sending a Diameter ASA command to the V-PCRF.

5. The V-PCRF proxies the ASA command to the H-PCRF.

6. The V-AF sends a Diameter STR command to the V-PCRF to indicate that the session has been terminated.

7. The V-PCRF proxies the Diameter STR command to the H-PCRF.

8. The V-PCRF proxies the Diameter STA command to the V-AF.

9. The H-PCRF responds by sending a Diameter STA command.

When the H-PCRF receives event triggers related to specific actions that the AF has subscribed to, the H-PCRF initiates the AF session modification procedure to notify the AF of these specific actions. For each Afsession bound to the modified IP-CAN session that has subscribed to these specific actions, steps 10-13 are executed instead of steps 2-9:

10. If the H-PCRF is notified of an event in the access network that has to be notified to the V-AF for an AF session, the H-PCRF informs of the event by sending a RAR command to the V-PCRF.

11. The V-PCRF proxies the RAR command to the V-AF.

12. The V-AF responds by sending a RAA command to the V-PCRF.

13. The V-PCRF proxies the RAA to the H-PCRF.

14. Steps 12 to 18 in figure 4.3.2.1.1 are executed.