A.6 PCC procedures over S9 Reference Point

29.2153GPPPolicy and Charging Control (PCC) over S9 reference pointRelease 17Stage 3TS

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

A.6.1 Session Establishment over S9

A.6.1.1 EPC-Routed Traffic

A.6.1.1.1 S9 Session Establishment Triggered by H-PCRF

When the H-PCRF receives an IP-CAN Session establishment from the PCEF including either the H(e)NB-Local-IP-Address AVP or UE-Local-IP-Address AVP and the user is roaming in a Visited Network, the H-PCRF determines if an S9 session exists for this IP-CAN session. If the S9 session is not already established, the H-PCRF shall trigger an S9 session establishment procedure from the V-PCRF.

The H-PCRF shall send a TER command to V-PCRF to trigger the S9 session establishment procedure. The H-PCRF shall include in the TER command the IMSI within the Subscription-Id AVP, the UDP port within UDP-Source-Port AVP if available and the PDN information within the Called-Station-ID AVP if available. The H-PCRF shall include the Auth-Session-State AVP set to NO_STATE_MAINTAINED.

For WLAN scenario, the H-PCRF shall also include the UE local IP address within the UE-Local-IP-Address AVP.

For H(e)NB scenario, the H-PCRF shall also include the H(e)NB Local IP address within the HeNB-Local-IP-Address AVP.

The V-PCRF shall reply the H-PCRF with a TEA command, and initiate the S9a Session establishment procedure as described in clause A,5,1.1 (when no S9a session exists) or the S9a Session modification procedure as described in clause A.5.3.1.1 (when there already exists an S9a session).

When the V-PCRF receives a TER command from the H-PCRF to trigger an S9 session establishment procedure for the EPC-routed traffic for a user, if the V-PCRF determines that the S9 session is being established for the NSWO traffic for the user by the V-PCRF, the V-PCRF.shall send a TEA command including the Experimental-Result AVP with the Experimental-Result. Code AVP set to DIAMETER_ERROR_ONGOING_SESSION_ESTABLISHMENT (5471) to the H-PCRF. When the H-PCRF receives this error, it shall send a RAR command to V-PCRF to trigger an S9 subsession establishment procedure after the S9 session of the user is established as defined in clause A.6.3.1.0.

A.6.1.1.2 S9 Session Establishment

When the V-PCRF receives one of the following triggers:

– a Gateway Control Session Establishment from the BBERF (ePDG) with UE Local IP address

– an IP-CAN Session Establishment from the PCEF with UE Local IP address

– a Gateway Control Session Establishment from the BBERF(S-GW) with H(e)NB IP address

– an IP-CAN Session Establishment from the PCEF with H(e)NB IP address

– an S9a Session Establishment from the BPCF.

then the V-PCRF determines if an S9 session is already present for that subscriber. If the S9 session is not already established, the V-PCRF initiates an S9 Session Establishment Procedure. Otherwise, it initiates an S9 Subsession Establishment Procedure as described in clause A.6.3.1.2.

The V-PCRF shall send a CCR command following current S9 procedures including the information received over Gx, Gxx or S9a.

If the procedure is initiated by the BPCF the V-PCRF shall map the S9a session-id to the corresponding S9 session-id. If the procedure is initiated by the BBERF/PCEF, the V-PCRF shall map the Gxx/Gx session-id to the corresponding S9 session-id (case 2a) or S9 subsession-id (case 1 and case 2b).

If the procedure is initiated by the BBERF or PCEF, the V-PCRF shall initiate the S9a session establishment trigger procedures as described in clause A.5.1.1.1 and keep the mapping between the S9a session-id and the S9 session-id (case 2a) or S9 subsession-id (case 2b and H(e)NB scenario).

To acknowledge the CCR command, the H-PCRF shall send a CCA command including the result code within Result-Code AVP. The H-PCRF provides the QoS-Rule-Install AVP to include the applicable QoS Rules and, if available, the ePDG IP address derived from the ePDG IP address IE as defined in clause 7.2.1 of 3GPP TS 29.274 [22] (for S2b access) or used as the IPSec tunnel endpoint with the UE (for untrusted S2c access) within AN-GW-Address AVP or, if available, the PDN GW IP address (for trusted S2c access) within 3GPP-GGSN-Address AVP used as the endpoint of the DSMIPv6 IPv4 user plane tunnel with the UE (IPv4 address) or used as the endpoint of the DSMIPv6 IPv6 user plane tunnel with the UE within the 3GPP-GGSN-IPv6-Address AVP (IPv6 address).

A.6.1.2 NSWO Traffic

When the V-PCRF receives an S9a* Session Establishment from the BPCF, then the V-PCRF determines if an S9 session is already present for that subscriber. If the S9 session is not already established, the V-PCRF initiates an S9 Session Establishment Procedure in order to establish an S9 subsession below; otherwise, the V-PCRF initiates an S9 Session Modification Procedure as described in clause A.6.3.2.2.

The V-PCRF shall send a CCR command following current S9 session establishment procedures including the information received over S9a reference point.

The V-PCRF shall map the S9a* session to the corresponding S9 subsession.

The H-PCRF shall acknowledge the request using a CCA command.

A.6.2 Session Termination over S9

A.6.2.1 EPC-Routed traffic

A.6.2.1.1 S9 Session Termination initiated by the H-PCRF

This procedure is initiated by the H-PCRF to terminate an S9 session when the last IP-CAN session related to a subscriber is terminated. The procedure described in clause 4.5.2.4 shall apply. The V-PCRF shall apply the corresponding S9a session procedure according to clause A.5.

The V-PCRF shall send a CCR command with the CC-Request-Type AVP set to the value "TERMINATION_REQUEST".

To acknowledge the CCR command, the H-PCRF shall send a CCA command including the result code within Result-Code AVP.

A.6.2.1.2 S9 Session Termination initiated by the V-PCRF

This procedure is initiated by the V-PCRF to terminate an S9 session when the V-PCRF receives a Gateway Control Session Termination from the BBERF corresponding to the last PDN connection related to a subscriber. The procedure described in clause 4.5.2.3 shall apply. The V-PCRF shall initiate the corresponding S9a session procedure as described in clause A.5.

The V-PCRF shall send a CCR command with the CC-Request-Type AVP set to the value "TERMINATION_REQUEST".

To acknowledge the CCR command, the H-PCRF shall send a CCA command including the result code within Result-Code AVP.

A.6.2.2 NSWO Traffic

A.6.2.2.1 S9 Session Termination initiated by the V-PCRF

This procedure is initiated by the V-PCRF to terminate an S9 session when the V-PCRF receives an S9a* Session Termination procedure from the BPCF and it corresponds to the last S9 subsession for the roaming user.

The V-PCRF shall send a CCR command with the CC-Request-Type AVP set to the value "TERMINATION_REQUEST".

To acknowledge the CCR command, the H-PCRF shall send a CCA command including the result code within Result-Code AVP.

A.6.2.2.2 S9 Session Termination initiated by the H-PCRF

If the H-PCRF decides to terminate the IP-CAN session for the NSWO traffic due to an internal trigger or trigger from the SPR, and if the H-PCRF considers that the S9 session has to be terminated, the H-PCRF shall send an RAR command to the V-PCRF indicating the termination of the S9 session by including the Session-Release-Cause AVP at command level. The V-PCRF shall send a corresponding RAA command to the H-PCRF.

The V-PCRF shall trigger S9a* Session Termination procedure as defined in clause A.5.2.2.2.

A.6.3 Session Modification over S9

A.6.3.1 EPC-Routed traffic

A.6.3.1.0 S9 subsession establishment triggered by H-PCRF

When the H-PCRF receives an IP-CAN Session establishment from the PCEF including either the H(e)NB-Local-IP-Address AVP or UE-Local-IP-Address AVP and the user is roaming in a Visited Network, the H-PCRF determines if an S9 session exists for this IP-CAN session. If the S9 session is not established, the S9 session establishment procedure as described in clause A.6.1.1.1 applies. If the S9 session is already established, the H-PCRF shall trigger an S9 subsession establishment procedure from the V-PCRF.

The H-PCRF shall send a RAR command to V-PCRF to trigger the S9 subsession establishment procedure. The H-PCRF shall include in the RAR command the IMSI within the Subscription-Id AVP, the PDN information within the Called-Station-ID AVP if available and the UDP port within UDP-Source-Port AVP if available.

For WLAN scenario, the H-PCRF shall also include the UE local IP address within the UE-Local-IP-Address AVP.

For H(e)NB scenario, the H-PCRF shall also include the H(e)NB Local IP address within the HeNB-Local-IP-Address AVP.

The V-PCRF shall reply the H-PCRF with a RAA command, and initiate the S9a Session establishment procedure as described in clause A,5,1.1 (when no S9a session exists) or the S9a Session modification procedure as described in clause A.5.3.1.1 (when there already exists an S9a session).

A.6.3.1.1 S9 Session Modification initiated by the H-PCRF

The H-PCRF may initiate an S9 Session Modification by sending a RAR command in the following cases:

– An IP-CAN Session Modification is triggered by the PCEF

– In response to information provided to the H-PCRF via the Rx reference point

– From a trigger from the SPR

– Based on internal policies

– An IP-CAN Session Establishment. In this case, the procedure described in clause A.6.3.1.0 applies.

The H-PCRF may provide the local UE IP Address (WLAN scenario), the H(e)NB Local IP address (H(e)NB scenario), the UDP port and corresponding event triggers, if provided by the PCEF by including the Event-Report-Indication AVP within the Subsession-Decision-Info AVP (case 1) when this information has changed in the RAR command.

If the QoS information is changed, the H-PCRF may include QoS rules within the QoS-Rule-Install AVP at command level (case 2a) or within the Subsession-Decision-Info AVP (case 1, case 2b).

The V-PCRF shall initiate the corresponding S9a session procedure according to clause A.5.

When the RAR command includes QoS rules, the V-PCRF shall validate the QoS information contained within the QoS rules using the current procedures.

A.6.3.1.2 S9 Session Modification initiated by the V-PCRF

When the V-PCRF receives one of the following triggers:

– an S9a Session Establishment from the BPCF.

– an S9a Session Modification from the BPCF (e.g. when the BBF network cannot sustain the allocated bandwidth) according to clause A.5.3.1.2

– a Gateway Control Session Establishment from the BBERF (case 2b, case 2a) and there is an S9 Session established

– a Gateway Control Session Modification from the BBERF (case 2b, case 2a)

– a Gateway Control Session Termination from the BBERF that does not correspond to the last S9 subsession (applicable only to WLAN, case 2b)

NOTE: In the above scenarios, BBERF refers to both ePDG and SGW.

– an IP-CAN Session Establishment from the PCEF and there is an S9 session established

– an IP-CAN Session Modification from the PCEF

– an IP-CAN Session Termination from the PCEF that does not correspond to the last S9 subsession

then the V-PCRF shall send a CCR command following current S9 procedures including the information received over Gx, Gxx or S9a.

NOTE: For H(e)NB scenario, when the S9 Session Modification is generated by the BPCF, the V-PCRF modifies all the S9 sessions affected by the S9a session modification.

A.6.3.2 NSWO traffic

A.6.3.2.1 S9 Session Modification initiated by the H-PCRF

Solicited in response to information provided to the H-PCRF via the Rx reference point or from a trigger from the SPR or based on internal policies, the H-PCRF may initiate an S9 Session Modification procedure by sending a RAR command.

If the H-PCRF considers that the S9 subsession has to be terminated, the H-PCRF shall send an RAR command to the V-PCRF indicating the termination of the S9 subsession by including the Session-Release-Cause AVP within the Subsession-Decision-Info AVP.

If the QoS information is changed, the H-PCRF may install or modify PCC rules by including the Charging-Rule-Install AVP or remove the PCC rules by including the Charging-Rule-Remove AVP within the Subsession-Decision-Info AVP.

A.6.3.2.2 S9 Session Modification initiated by the V-PCRF

The V-PCRF initiates an S9 session modification by sending a CCR command following the current S9 session modification procedures including the information received over S9a reference point in the following cases:

– the V-PCRF receives an S9a* Session Establishment from the BPCF as described in clause A.5.1.2.1 and an existing S9 session for the roaming user already exists with the H-PCRF;

– the V-PCRF receives an S9a* Session Modification from the BPCF (e.g. when the BBF network cannot sustain the allocated bandwidth) according to clause A.5.3.2.2;

– the V-PCRF receives an S9a* Session Termination from the BPCF as described in clause A.5.2.2.1 and it does not correspond to the last S9 subsession.

A.6.4 Provisioning and validation of QoS information

A.6.4.1 EPC-Routed traffic

When the H-PCRF provides QoS rules to the V-PCRF and the V-PCRF cannot accept the QoS required for the QoS rules, the V-PCRF includes the QoS-Rule-Report AVP to indicate the QoS Rules that were not accepted including Rule-Failure-Code AVP set to UNSUCCESSFUL_QOS_VALIDATION value and may additionally propose the acceptable QoS to the H-PCRF as per normal S9 procedures.

A.6.4.2 NSWO traffic

When the H-PCRF provides PCC rules to the V-PCRF and the V-PCRF cannot accept the QoS required for the PCC rules, the V-PCRF includes the Charging -Rule-Report AVP to indicate the PCC Rules that were not accepted including Rule-Failure-Code AVP set to UNSUCCESSFUL_QOS_VALIDATION value and may additionally propose the acceptable QoS to the H-PCRF as per normal S9 procedures.