4.5.1 Non-Roaming and Home Routed cases

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

4.5.1.1 New Gateway Control Session Establishment

The following signalling flow describes an example of a new BBERF initiating a GW control session establishment associated with an existing IP-CAN session.

Figure 4.5.1.1.1: Gateway Control Session Establishment during BBERF relocation

1. The target BBERF receives a message or indication to establish a Gateway Control session

2. The target BBERF initiates a Gateway Control session with the H-PCRF by sending a CCR using the CC-Request-Type AVP set to the value INITIAL_REQUEST to the H-PCRF. The target BBERF provides information as detailed in clause 4a.5.1 of 3GPP TS 29.212 [9].

When the UE is roaming, the following steps are executed instead of step 2:

2a. The target BBERF initiates a Gateway Control session with the V-PCRF by sending a CCR using the CC-Request-Type AVP set to the value INITIAL_REQUEST to the V-PCRF. The target BBERF provides information as detailed in clause 4a.5.1 of 3GPP TS 29.212 [9].

2b. The V-PCRF determines based on the UE identity information that the request is for a roaming user. The V-PCRF checks whether the V-PCRF is required to send the request to the H-PCRF based on the roaming agreements.

2c. For case 2a:

– The V-PCRF sends a CCR to the H-PCRF with the CC-Request-Type AVP set to the value UPDATE_REQUEST. The V-PCRF includes in the CCR the information received in step 2a. The V-PCRF includes the BBERF identity by including the AN-GW-Address AVP at command level.

For case 2b:

– If the Session-Linking-Indicator AVP is not received, or it indicates SESSION_LINKING_IMMEDIATE, the V-PCRF sends the CCR command to the H-PCRF with the CC-Request-Type AVP set to the value UPDATE_REQUEST. The V-PCRF includes the Subsession-Enforcement-Info AVP within the CCR command with allocated S9 subsession identifier assigned by the V-PCRF for this PDN connection within the Subsession-Id AVP, the Subsession-Operation AVP set to the value MODIFICATION, the BBERF identity within AN-GW-Address AVP.

– If the Session-Linking-Indicator AVP is received indicating that the session linking has to be deferred, the V-PCRF sends a CCR to the H-PCRF with the CC-Request-Type AVP set to the value UPDATE_REQUEST. The V-PCRF includes the Subsession-Enforcement-Info AVP within the CCR with a new S9 subsession identifier assigned by the V-PCRF to this Gateway Control Session within the Subsession-Id AVP, the Subsession-Operation AVP set to the value ESTABLISHMENT and the Session-Linking-Indicator AVP set to the value “SESSION_LINKING_DEFERRED”.

3. The H-PCRF stores the information received in the Diameter CCR.

4. If the Session-Linking-Indicator AVP was received indicating that the session linking has to be deferred, the linking between the Gateway Control Session and the Gx session shall be deferred. Otherwise, based on the information received the H-PCRF identifies multiple BBERF sessions for a particular IP-CAN session.

5. The H-PCRF derives applicable PCC/QoS rules based on the BCM mode as defined in clause 4a.5.7 of 3GPP TS 29.212 [9].

6. The H-PCRF stores the selected QoS Rules and PCC Rules. For non-roaming users the H-PCRF selects the Bearer Control Mode that will apply during the Gateway Control session.

7. The H-PCRF acknowledges the Gateway Control Session by sending a Diameter CCA. The H-PCRF includes the selected BCM if applicable, the QoS rules and event triggers.

When the UE is roaming, the following steps are executed instead of step 7:

7a. The H-PCRF acknowledges the Gateway Control Session by sending a Diameter CCA to the V-PCRF. The H-PCRF includes applicable QoS rules and also event triggers. The H-PCRF also includes the AN-GW-Address AVP if the QoS rules are applicable for a single BBERF.

7b. The V-PCRF enforces visited operator policies regarding QoS authorization requested by the H-PCRF as indicated by the roaming agreements.

7c. If the V-PCRF denies an authorization, it informs the H-PCRF and may provide the acceptable QoS Information for the service.

7d. The H-PCRF may provide new or modified QoS rules to the V-PCRF.

7e. The V-PCRF acknowledges the Gateway Control Session and provisions, when applicable, the selected BCM, policy decisions and event triggers to the target BBERF.

8. The BBERF installs the received QoS Rules.

9. The target BBERF establishes an indication for a Gateway control session response.

4.5.1.2 PCEF IP-CAN session modification – Handover

The following signalling flow describe the case when an indication of handover is received by the PCEF and the H-PCRF derives QoS rules based on the type of BBERF (primary/non-primary).

Figure 4.5.1.2.1: PCEF IP-CAN session modification – Handover

1. The PCEF receives a message or indication that a handover occurred

2. The PCEF initiates an IP-CAN Session Modification procedure by sending a CCR using the CC-Request-Type AVP set to the value UPDATE_REQUEST to the H-PCRF. The PCEF includes the AN_GW_CHANGE event trigger, and if applicable the IP-CAN_CHANGE event trigger as well, to indicate that handover has occurred.

3. The H-PCRF stores the information received in the Diameter CCR.

4. If there is a pending gateway control session to be linked to a Gx session, the H-PCRF shall perform the session linking according to clause 4a.5.6 of 3GPP TS 29.212 [9] for the non-roaming case. Based on the information received the H-PCRF reclassifies primary/non-primary BBERFs according to the procedures defined in clause 4a.5.7 of 3GPP TS 29.212 [9].

5. The H-PCRF derives PCC rules for the PCEF, and QoS rules for the new reclassified primary BBERF, based on the BCM mode of the GW control session as defined in clause 4a.5.7 of 3GPP TS 29.212 [9].

6. The H-PCRF stores the selected QoS Rules and PCC Rules.

7. The H-PCRF acknowledges the IP-CAN session modification request by sending a Diameter CCA to the PCEF. The H-PCRF includes updated PCC rules and event triggers (if applicable).

8. The H-PCRF initiates a Gateway Control and QoS Rules Provision procedure by sending a Diameter RAR. The H-PCRF includes the selected BCM if applicable, the QoS rules and event triggers.

When the UE is roaming, the following steps are executed instead of step 8:

8a. The H-PCRF initiates a Gateway Control and QoS Rules Provision procedure to the V-PCRF by sending a Diameter RAR to the V-PCRF. The H-PCRF sends applicable QoS rules based on the BBERF type (primary/non-primary) and BCM mode selected as defined in clause 4a.5.9 of 3GPP TS 29.212 [9]. The H-PCRF includes the AN-GW-Address AVP if the QoS rules are applicable only for a single BBERF. If the QoS rules are applicable for all BBERF sessions this AVP is omitted.

8b. The V-PCRF enforces visited operator policies regarding QoS authorization requested by the H-PCRF as indicated by the roaming agreements.

8c. If the V-PCRF denies an authorization, it informs the H-PCRF and may provide the acceptable QoS Information for the service by including in the RAA command the QoS-Rule-Report AVP to indicate the QoS Rules that were not accepted, the Rule-Failure-Code AVP set to UNSUCCESSFUL-QoS-VALIDATION, and the QoS-Information AVP.

8d. The H-PCRF may provide new or modified QoS rules to the V-PCRF.

8e. The V-PCRF initiates the Gateway Control Session and QoS rules provisions, when applicable, the selected BCM, policy decisions and event triggers to the target BBERF.

9. The BBERF installs the received QoS Rules.

10. The target BBERF acknowledges the RAR command by sending a Diameter RAA command to the PCRF.

When the UE is roaming, the following steps are executed instead of step 10:

10a.The BBERF acknowledges the Gateway Control and QoS Rules Provision request by sending a Diameter RAA to the V-PCRF.

10b. The V-PCRF acknowledges the Gateway Control and QoS Rules Provision request by sending a Diameter RAA to the H-PCRF.

4.5.1.3 PCEF IP-CAN session modification – S2c-based IP flow mobility

The following signalling flow describes an example of S2c-based IP flow mobility. In this case, the H-PCRF receives an IP flow mobility event by the PCEF and derives QoS rules based on the IP flow mobility routing rules.

Figure 4.5.1.3.1: PCEF IP-CAN session modification – S2c-based IP flow mobility

1. The PCEF receives a message or indication that an IP flow mobility event occurred

2. The PCEF initiates an IP-CAN Session Modification procedure by sending a CCR using the CC-Request-Type AVP set to the value UPDATE_REQUEST to the H-PCRF. The PCEF includes the ROUTING_RULE_CHANGE event trigger to indicate that a change in the IP flow mobility routing rules has occurred. The PCEF includes in the CCR the Routing-Rule-Install and/or Routing-Rule-Removal AVPs.

3. The H-PCRF stores the information received in the Diameter CCR.

4. The H-PCRF derives PCC rules for the PCEF, and QoS rules for the BBERF(s), based on the BCM mode of the GW control session and the IP flow mobility routing rules as defined in clause 4a.5.7 of 3GPP TS 29.212 [9]

5. The H-PCRF stores the selected PCC/QoS Rules.

6. The H-PCRF acknowledges the IP-CAN session modification request by sending a Diameter CCA to the PCEF. The H-PCRF includes updated PCC rules and event triggers (if applicable).

7. The H-PCRF initiates a Gateway Control and QoS Rules Provision procedure by sending a Diameter RAR. The H-PCRF includes the QoS rules and event triggers.

When the UE is roaming, the following steps are executed instead of step 7:

7a. The H-PCRF initiates a Gateway Control and QoS Rules Provision procedure to the V-PCRF by sending a Diameter RAR to the V-PCRF. The H-PCRF sends applicable QoS rules based on BCM mode selected as defined in clause 4a.5.9 of 3GPP TS 29.212 [9]. The H-PCRF includes the AN-GW-Address AVP identifying the BBERF involved in the exchange of the IP flows described by the received IP flow mobility routing rules

7b. The V-PCRF enforces visited operator policies regarding QoS authorization requested by the H-PCRF as indicated by the roaming agreements.

7c. If the V-PCRF denies an authorization, it informs the H-PCRF and may provide the acceptable QoS Information for the service by including in the RAA command the QoS-Rule-Report AVP to indicate the QoS Rules that were not accepted, the Rule-Failure-Code AVP set to UNSUCCESSFUL-QoS-VALIDATION, and the QoS-Information AVP.

7d. The H-PCRF may provide new or modified QoS rules to the V-PCRF.

7e. The V-PCRF initiates the Gateway Control Session and QoS rules provisions, when applicable, policy decisions and event triggers to BBERF.

8 Step 9 through step 10b: as specified in Figure 4.5.1.2.1: PCEF-initiated IP-CAN session modification‑ Handover are executed, as needed. If the IP flows were moved from one access to another (e.g. 3GPP to WLAN, or vice versa), the PCRF may also initiate a RAR command towards BBERF#1 to modify or release the related resources associated with the flows that were moved to BBERF#2.

4.5.1.4 Gateway Control Session Establishment and PCEF IP-CAN session modification – S2c-based IP flow mobility

The following signalling flow describes an example of S2c-based IP flow mobility. In this case, the H-PCRF receives a Gateway Control session establishment by a BBERF and an IP flow mobility event by the PCEF. H-PCRF associates the IP‑CAN session to multiple Gateway Control Sessions and derives QoS rules based on the IP flow mobility routing rules.

Figure 4.5.1.4.1: Gateway Control Session Establishment and PCEF IP-CAN session modification – S2c-based IP flow mobility

1. Step 1 through step 10: as specified in Figure 4.4.1.1: Gateway Control Session Establishment are executed, as needed. The Gateway Control Session is established for BBERF #2. The Gateway Control Session for BBERF #1 was previously established.

NOTE: If the Gateway Control Session is established for WLAN access, only case 2a is possible.

2. The PCEF receives a message or indication that an IP flow mobility event occurred.

3. The PCEF initiates an IP-CAN Session Modification procedure by sending a CCR using the CC-Request-Type AVP set to the value UPDATE_REQUEST to the H-PCRF. The PCEF includes the ROUTING_RULE_CHANGE event trigger to indicate that a change in the IP flow mobility routing rules has occurred. The PCEF includes in the CCR the Routing-Rule-Install and/or Routing-Rule-Removal AVPs.

4. The H-PCRF stores the information received in the Diameter CCR.

5. The H-PCRF does not differentiate between primary and non-primary BBFs. H-PCRF derives PCC rules for the PCEF, and QoS rules for the BBERF(s), based on the BCM mode of the GW control session and the IP flow mobility routing rules as defined in clause 4a.5.7 of 3GPP TS 29.212 [9]

6. Step 5 through step 8: as specified in Figure 4.5.1.3.1: PCEF-initiated IP‑CAN session modification‑ IP Flow mobility are executed, as needed.