This clause describes the detection process at the UP function that identifies the packets belonging to a bearer, service data flow or IP-CAN/TDF session. The CP function is responsible for instructing the UP function about how to detect user data traffic belonging to a Packet Detection Rule (PDR). The other parameters provided within a PDR describe how the UP function shall treat a packet that matches the detection information.

The CP function controls the traffic detection at the UP function by providing detection information for every PDR. Detection information is a combination of:

• UE IP address;
• F-TEIDu;
• SDF filters as defined in TS 23.203;
• Application ID (referring to an application detection filter) as defined in TS 23.203.

The following Table 5.2.2-1 lists the possible combinations of the traffic detection information for the different UP functions and usage scenarios.

If functional split of SGW into SGW-C and SGW-U is supported, the overall functionality of offline charging support as defined by TS 23.401 and TS 32.251 shall be preserved. If functional split of PGW into PGW-C and PGW-U is supported, the overall functionality of online and offline charging as defined by TS 32.251, and of usage monitoring control as defined by TS 23.401, TS 23.203 shall be preserved. If functional split of TDF into TDF-C and TDF-U is supported, the overall functionality of online and offline charging as defined by TS 32.251, and of usage monitoring control as defined by TS 23.203 shall be preserved. The following principles shall apply in case of a functional split:

• The Gx, Sd, Gy, Gyn, Gz, Gzn interfaces as well as the interface between SGW and OFCS shall be terminated in the CP function (SGW-C/PGW-C/TDF-C). This implies that the CP function shall support those interfaces towards OCS/OFCS and PCRF, based on information received at the corresponding CP function as well as gathered user-plane related information received from the UP function as further described below.
• There is no impact on PCRF, OCS and OFCS compared to non-split architecture.
• All bearer/traffic flow level, session level and subscriber related information remains at the CP function, and only usage information is requested from UP function.

Triggered by the PCC/ADC rules received from the PCRF or preconfigured information available at PGW-C/TDF-C/SGW-C, as well as from the OCS for online charging via Credit-Control session mechanisms, the CP function (PGW-C/TDF-C/SGW-C) shall provide Usage Reporting Rules to the UP function (PGW-U/TDF-U/SGW-U) for controlling how usage reporting is performed. The CP function shall request the report of the relevant usage information for Usage Monitoring, based on Monitoring Keys and triggers which are specified in TS 23.203 and TS 29.212. Each Usage Reporting Rule requested for usage monitoring control is associated with the PDR(s) whose traffic is to be accounted under this rule. The CP function shall generate the Usage Reporting Rule for each Monitoring-key within the active PCC/ADC rule(s), either preconfigured or received from the PCRF, and also shall keep the mapping between them. Multiple Usage Reporting Rules may be associated with the same PDR. The CP function shall request the report of the relevant usage information for offline and online charging, based on Charging keys and additional triggers which are specified in TS 32.251. Each Usage Reporting Rule requested for offline or online charging is associated with the PDR(s) whose traffic is to be accounted under this rule. The CP function shall generate the Usage Reporting Rule for each Charging key or Sponsor Identity (if applicable) within the active PCC/ADC rule(s), either preconfigured or received from the PCRF, and also shall keep the mapping between them. Multiple Usage Reporting Rules may be associated with the same PDR. The CP function shall also provide reporting trigger events to the UP function for when to report usage information. The reporting trigger events (e.g. triggers, threshold information etc.) shall be supported for the session (IP-CAN/TDF) level reporting as well as on Rule level basis as determined by the CP function. The triggers may be provided as a volume, time or event to cater for the different charging/usage monitoring models supported by the TS 23.203 for usage monitoring and by TS 32.251 for offline and online charging. The CP function shall decide on the thresholds value(s) based on allowance received from PCRF, OCS or based on local configuration. In some cases, the same Usage Reporting Rule can be used for different purposes (for both usage monitoring and charging), e.g. in case the same set of PDR(s), measurement method, trigger event, threshold, etc. apply. Similarly a reported measurement can be used for different purposes by the CP function.

The UP function shall support reporting of usage information to the CP function. The UP function shall be capable to support reporting based on different triggers, including:

• Periodic reporting with period defined by the CP function.
• Usage thresholds provided by the CP function.
• Report on demand received from the CP function.

The CP function shall make sure that the multiple granularity levels required by the reporting keys in the Usage Reporting rules satisfy the following aggregation levels without requiring a knowledge of the granularity levels by the UP function:

• Session level reporting (IP-CAN/TDF session);
• Bearer (for charging)/traffic flow (for both charging and usage monitoring) level reporting as defined by the reporting keys in the Usage Reporting Rule (see the description above).

Based on the mapping between Monitoring-key and PCC/ADC rule stored at the CP function, the CP function shall combine the reported information with session and subscriber related information which is available at the CP function, for Usage Monitoring reporting over the corresponding Gx, Sd interfaces. Based on the mapping between Rating Group or Sponsor Identity and PCC/ADC rule stored at the CP function, the CP function shall combine the reported information with session and subscriber related information which is available at the CP function, for offline and online charging reporting over the corresponding Gy, Gyn, Gz, Gzn interfaces. This functionality is specified in TS 32.240. The usage information shall be collected in the UP function and reported to the CP function as defined in 5.3.3, based on Monitoring Keys and triggers which are specified in TS 23.203 and TS 29.212.

When the UE moves to ECM-IDLE state and the SGW-C decides to activate buffering in SGW-U for the session, it shall also instruct the SGW-U to measure the number of packets/bytes that are buffered or discarded in SGW-U and the criteria for reporting within the Usage Reporting Rule. Once the trigger of reporting is met, the SGW-U shall inform the SGW-C by reporting usage information. The SGW-C can then inform the PGW-C as described in TS 23.401. When the PGW-C determines to stop the charging and usage monitoring actions for the PDN connection, it shall indicate the PGW-U to stop collecting the usage information. PGW-C sends an Sx session modification request message to the PGW-U and modifies all the Usage Reporting Rules within the PDN connection to indicate the usage collection shall be stopped. When PGW-C determines to continue the charging action for the PDN connection, it sends an Sx session modification request message to the PGW-U and modifies all the Usage Reporting Rules within the PDN connection to indicate the usage collection shall be resumed.

Allocation and release of F-TEIDu is performed by SGW and PGW when a bearer needs to be established or released. If functional split into SGW-C/PGW-C and SGW-U/PGW-U is supported, F-TEIDu allocation and release is done in the UP function, as described in clause 5.4.3 below. The support of F-TEIDu allocation by the UP function is mandatory.

The SGW-U, the SGW-U shall manage the SGW F-TEIDu space, including ensuring that the allocated F-TEIDu(s) are unique as described in TS 29.060. In case of bearer activation, the SGW-C shall request SGW-U to allocate F-TEIDu(s) for the applicable SGW-U reference points and provide them to the SGW-C. The SGW-C shall provide the F-TEIDu(s) to other network entities as described in TS 23.401 in order to complete the bearer establishment. In case of bearer deactivation, the SGW-C shall request SGW-U to release F-TEIDu(s) for the bearer. The PGW-U shall manage the PGW F-TEIDu space, including ensuring that the allocated F-TEIDu(s) are unique as described in TS 29.060. In case of bearer activation, the PGW-C shall request PGW-U to allocate F-TEIDu(s) for the applicable PGW-U reference points and provide them to the PGW-C. The PGW-C shall provide the F-TEIDu(s) to other network entities as described in TS 23.401 and TS 23.402 in order to complete the bearer establishment. In case of bearer deactivation, the PGW-C shall request PGW-U to release F-TEIDu(s) for the bearer.