4.9 Traffic Steering Control Procedures over St reference point

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

4.9.1 St Session Establishment

In the following procedure, the PCRF initiates the St session establishment procedure and provides the traffic steering control informaiton to the TSSF due to the PCRF determines that the traffic steering control is needed for the IP-CAN session.

Figure 4.9.1.1: St Session Establishment

1. The PCRF initiates session between the PCRF and TSSF and provisions the applicable ADC Rules for the corresponding IP-CAN session by sending a Diameter TSR to the TSSF, including the Request-Type AVP set to the value "0" and other parameters as defined in subclause 4c.4.1 of 3GPP TS 29.212 [9].

2. The TSSF installs and/or activates the ADC rules and acknowledges to the PCRF by sending a Diameter TSA command.

4.9.2 St Session Modification

In the following procedure, the PCRF updates the traffic steering control informaiton at the TSSF due to the PCRF determines that the traffic steering control information needs to be update for the IP-CAN session (e.g. Subscription is changed) or notifies the TSSF that the IPv4 address is allocated/released.

Figure 4.9.2.1: St Session Modification

1. The PCRF provisions the new, updated and/or requests to remove ADC rules for the corresponding IP-CAN session or notifies the TSSF that the IPv4 address is allocated/released by sending a Diameter TSR command to the TSSF, including the Request-Type AVP set to the value "1" and other parameters as defined in subclause 4c.4.1 or 4c.4.4 of 3GPP TS 29.212 [9].

2. The TSSF installs, modifies and/or removes the ADC rules or activates and/or deactivates the ADC rules and acknowledges to the PCRF by sending a Diameter TSA commands.

4.9.3 St Session Termination

In the following procedure, the the PCRF initiates the St session termination procedure and removes all the traffic steering control informaiton to the TSSF due to the corresponding IP-CAN session is terminated or the H-PCRF determines that the traffic steering control information is not needed for the IP-CAN session any longer (e.g. Subscription has changed).

Figure 4.9.3.1: St Session Termination

1. The PCRF sends an STR to the TSSF to terminate the session between the PCRF and the TSSF.

2. The TSSF removes/deactivates all the ADC Rules which are applied to the session.

3. The TSSF sends an STA to acknowledge the STR.

4.9.4 St notification initiated by the TSSF

In the following procedure, the TSSF reports the ADC rule error when the ADC rule can’t be enforced any longer.

Figure 4.9.4.1: St notification initiated by the TSSF

1. The TSSF reports the ADC rules error by sending a Diameter TNR command to the PCRF as defined in subclause 4c.4.3 of 3GPP TS 29.212 [9].

2. The PCRF acknowledges to the TSSF by sending a Diameter TNA command.