S.5 Functional description

23.2033GPPPolicy and charging control architectureRelease 17TS

S.5.1 Overall description

The purpose of PCC convergence is to enable the policy and charging control for NSWO traffic from 3GPP UE connected to the fixed broadband access network and for the traffic from fixed devices with where the PCRF controls directly the network element(s) in the fixed broadband access without the mediation of a different policy server, such as the BPCF defined in TS 23.139 [29]. In this release, EPC-routed traffic from 3GPP UE connected to connected fixed broadband access network is considered outside the scope.

The binding mechanism, credit management, reporting, usage monitoring, termination actions, service data flow prioritization, ADC Rule definition and operations, PCC Rule definition and operations and standardized QoS characteristics as defined in clause 6.1 shall apply.

Handling of packet filters provided to the UE by the PCEF as defined in clause 6.1.9 is not applicable for Fixed Broadband Access.

S.5.1.1 IP-CAN Session

For routed mode RG with NAT, one IP-CAN session shall be established for each corresponding Subscriber IP session on the IP-Edge for the IPv4 address and/or IPv6 address or IPv6 prefix assigned to the RG.

In case of routed mode RG when the PPP pass-through feature is enabled (see requirement R-10 in TR‑124 Issue 3 [34b]) an IP-CAN session shall be established for the each single fixed device starting the PPP session. In this case the 3GPP UE does not have Subscriber IP session in IP-Edge.

For bridged mode RG, one IP-CAN session shall be established for each corresponding Subscriber IP session on the IP-Edge for each IPv4 address and/or IPv6 address or IPv6 prefix assigned to the fixed device or 3GPP UE which established a Subscriber IP session in fixed broadband network.

For routed mode RG with IPv6 when stateless IPv6 address autoconfiguration is used by the end-device behind the RG, one IP-CAN session shall be established for each corresponding Subscriber IP session on the IP-Edge for the IPv6 prefix assigned to the RG. When stateful IPv6 address configuration is used by the end-devices, one IP-CAN session may be established for each end-device.

For routed mode RG, the successful completion of 3GPP-based access authentication and assignment of IP address to the 3GPP UE shall not result in any IP-CAN session establishment if the IP address assignment does not result in a new Subscriber IP Session in the IP-Edge. In this case the pre-existent IP-CAN session for the RG is used.

A device connected to the RG (e.g. VoIP phones) may also initiate a Subscriber IP session when the RG is configured in bridge mode or when the PPP pass-through feature is enabled on the Routing RG (see requirement R-10 in TR‑124 Issue 3 [34b]).

S.5.1.2 Subscriber Identifier

The Subscriber ID represents the identity of the User.

For the 3GPP UE the Subscriber ID is the IMSI.

The Subscriber ID used by fixed device at establishment of Subscriber IP session in fixed broadband access network can be the Access Line Identifier (physical and logical circuit ID) or the username, for example when the Subscriber IP session is a PPP Session. For the RG and fixed device based on Broadband Forum specification, the Subscriber ID is defined in Broadband Forum WT 134 [31] specification.

S.5.1.3 Event triggers

The fixed broadband access network in the convergent scenario supports the Event triggering mechanisms described in clause 6.1.4. The event triggers applicable are listed in the following:

Table S.5.1.3-1: Event triggers

Event trigger	Description	Reported from	Condition for reporting
QoS change	The QoS of the Default Access Profile in AAA has changed	PCEF	PCRF
Out of credit (see note 1)	Credit is no longer available.	PCEF, TDF	PCRF
Enforced ADC rule request	TDF is performing an ADC rules request as instructed by the PCRF.	TDF	PCRF
Usage report	The IP-CAN/TDF session or the Monitoring key specific resources consumed by a UE either reached the threshold or needs to be reported for other reasons.	PCEF, TDF	PCRF
Start of application traffic detection and Stop of application traffic detection (see note 2)	The start or the stop of application traffic has been detected.	PCEF, TDF	PCRF
Credit management session failure (see note 1)	Transient/Permanent Failure as specified by the OCS	PCEF, TDF	Always set
NOTE 1: This event may apply only when Gy and/or Gyn are deployed. NOTE 2: This event may only be triggered by a PCEF enhanced with ADC.

S.5.1.4 Void

S.5.1.5 Void

S.5.1.6 Credit management

For the purpose of credit management of an IP-CAN session for a fixed devices or a 3GPP UE using NSWO, the description in clause 6.1.3 applies with the following exceptions: the subscription identity is provided by PCEF or TDF to the OCS as defined in S.5.1.2 and the applicable credit-reauthorization triggers are defined in the table S.5.1.6-1:

Table S.5.1.6-1: Credit re-authorization triggers

Credit re-authorization trigger	Description	Applicable for
Credit authorisation lifetime expiry (see note 1)	The OCS has limited the validity of the credit to expire at a certain time.	PCEF, TDF
Idle timeout (see note 1)	The service data flow identified by a PCC Rules or the application identified by an ADC Rule has been empty for a certain time.	PCEF, TDF
QoS changes	The QoS of the access network profile has changed.	PCEF
NOTE 1: This credit reauthorization triggers apply only when Gy and/or Gyn are deployed.

S.5.2 Policy and charging Control

S.5.2.1 Policy and charging control rule

The definition of PCC rule and PCC Rule operations in clauses 6.3.1 and 6.3.2 are applicable, except:

– PS to CS session continuity;

– User Location Report.

NOTE: The procedure for provisioning predefined PCC rules at the IP-Edge is out of 3GPP scope.

S.5.2.1a IP‑CAN session related policy information

Table 6.4 applies with the following exceptions:

– Authorized QoS per bearer and authorized MBR per QCI are not applicable for Fixed Broadband Access.

– Charging characteristics profile for 3GPP UE is not available at the PCEF/IP-Edge.

– No Charging Characteristics profile is defined for fixed devices.

S.5.2.2 Void

S.5.3 Void

S.5.4 Reflective QoS

The Fixed Broadband Network received the PCC rules from Gx reference point and as described in clauses S.3.3 and S.6.1.2 performs the appropriated mapping to Fixed Broadband access parameters. The mapping is outside the scope of 3GPP network and defined in TR-300 [37]. Fixed Broadband Access network currently supports the DSCP marking as specified in BBF TR-092 [40] for BRAS, in BBF TR-101 [35] for Access Nodes and Aggregation Nodes and in BBF TR-124 Issue 3 [34b] for the RG.

The solution is based on DSCP marking of packets traversing the Fixed Broadband Access network. The solution assumes functionality in the BBF domain, all these functions are out-of-scope for 3GPP; also, these functions may or may not be implemented depending on the agreement between 3GPP and Fixed Broadband Access operator, these functions are described for information only.

The downlink QoS treatment of the traffic in the PCEF is defined in clause S.6.1.2 and in TR-300 [37].

For the QoS treatment of the IP flow traffic from the UE to the IP-Edge, DSCP marking may be performed by the 3GPP UE by means of reflective QoS as defined in TS 23.139 [29], in particular:

– How to inform the UE, as part of 3GPP access authentication signalling, that reflective QoS shall be applied on all the traffic in the attached network as defined in clause 6.3.1 of TS 23.139 [29].

– How the UE creates a 5-tuple rule for uplink traffic as defined in clause 6.3.3 of TS 23.139 [29]. How the RG or the IP-Edge may implement protective measurements (e.g. per UE-bandwidth limitations in the RG or in the IP-Edge) as defined in clause 6.3.1 of TS 23.139 [29].

NOTE: The UE supporting reflective QoS always send this indication during the Access authentication procedure.

S.5.5 Policy Control

Policy control functionalities listed in clause 6.1.5: binding, gating control, event reporting, QoS control and Redirection are applicable for Fixed Broadband Access. There is no support for NW initiated or UE initiated bearer establishment procedures; policy control is performed locally at the PCEF or at the TDF.

If the PCRF provides authorized QoS for both, the IP‑CAN session and PCC rule(s), the enforcement of authorized QoS of the individual PCC rules shall take place first.

S.5.5.1 Default QoS Control

The BBF AAA may provide a default Access Profile QoS for the IP-CAN session that may contain QoS information.

The PCRF may provide dynamically the default QoS for the IP-CAN session to the PCEF over Gx or alternatively may provide a default QoS profile name for those cases when the default QoS profile is provisioned in the IP-Edge/PCEF. The PCEF enforces the default QoS or the default QoS profile for the IP-CAN session provisions over Gx. The PCEF does not enforce the default Access Profile QoS provided by BBF AAA for the IP-CAN session if PCRF is deployed.

The default QoS consists of a QCI and MBR.

The IP-Edge/PCEF shall be able to convert default QoS into Fixed Broadband Access QoS attribute values. In the IP-Edge, the QCI and optionally the ARP priority level is used to determine the DSCP code value or other transport specific information element and the MBR is used for bandwidth limitation for the DSCP code value. The PCEF/IP-Edge shall enforce first the QoS for the packets that matches a service data flow template in an installed PCC Rule for which specific QoS enforcement actions are provided then the IP-Edge/PCEF shall enforce the default QoS for all downlink and uplink traffic for the IP-CAN session.