4.4.4 Gateway Control Session Termination

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

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

4.4.4.1 BBERF-Initiated Gateway Control Session Termination

This procedure applies for case 2b, as defined in clause 4.0, whenever the BBERF detects a request for a PDN disconnection, mobility to other access or the termination of a pre-registration at the BBERF.

Figure 4.4.4.1.1: BBERF-Initiated Gateway Control Session Termination

1. The BBERF is requested to terminate its gateway control session. The form of the request to remove the gateway control session depends upon the type of the IP-CAN.

2. The BBERF sends a Diameter CCR message to the H-PCRF, indicating the gateway control session termination. The BBERF requests the termination of the DCC session using the CC-Request-Type AVP set to the value TERMINATION_REQUEST.

If the UE is roaming, then steps in 2a ~ 2b are executed instead of step 2:

2a. The BBERF sends a Diameter CCR message to the V-PCRF, indicating the gateway control session termination. The BBERF requests the termination of the DCC session using the CC-Request-Type AVP set to the value TERMINATION_REQUEST.

2b. For the case 2a or if this is the last subsession associated with the S9 session for the case 2b, the V-PCRF sends a Diameter CCR message to the H-PCRF to request the termination of the S9 session. Otherwise, if the gateway control session is locally handled at the V-PCRF, the V-PCRF continues from step 4b; if the gateway control session has a corresponding S9 subsession, then the V-PCRF sends a Diameter CCR message to the H-PCRF to request the termination of the corresponding S9 subsession.

3. The H-PCRF identifies the related IP-CAN session and performs update as necessary.

4. The H-PCRF acknowledges the session termination by sending a Diameter CCA message.

If the UE is roaming, then steps 4a ~ 4c are executed instead of step 4:

4a. If the H-PCRF receives the Diameter CCR message in step 2b, the H-PCRF acknowledges the session or subsession termination request by sending a Diameter CCA message to the V-PCRF.

4b. The V-PCRF identifies the related IP-CAN session and performs update as necessary.

4c. The V-PCRF acknowledges the session termination by sending a Diameter CCA message to the BBERF.

5. The BBERF sends a reply to the request to remove the gateway control session. The form of the reply depends upon the type of the IP-CAN.

4.4.4.2 PCRF-Initiated Gateway Control Session Termination

This procedure applies for case 2a, as defined in clause 4.0, when the PCRF detects that there is no remaining IP-CAN session at the PCRF.

Figure 4.4.4.2.1: PCRF-Initiated Gateway Control Session Termination

1. The H-PCRF is requested to terminate the gateway control session.

2. The H-PCRF sends a Diameter RAR message to the BBERF including a Session-Release-Cause AVP to indicate request for terminating the gateway control session.

If the UE is roaming, then steps in 2a ~ 2b are executed instead of Step 2:

2a. The H-PCRF sends a Diameter RAR message to the V-PCRF to indicate the termination of the S9 session including the Session-Release-Cause AVP.

2b. The V-PCRF sends a Diameter RAR message to the BBERF based on the termination request received from the H-PCRF to indicate the gateway control session termination.

3. The BBERF acknowledges the gateway control session termination request by sending a Diameter RAA message.

If the UE is roaming, then steps 3a ~ 3b are executed instead of Step 3:

3a. The BBERF acknowledges the gateway control session termination request by sending a Diameter RAA message to the V-PCRF.

3b. The V-PCRF sends a Diameter RAA message to the H-PCRF and acknowledges the request for terminating the S9 session corresponding to the gateway control session.

4. The BBERF follows the BBERF-initiated gateway control session termination procedures described in clause 4.4.4.1 to terminate the gateway control session.