3GPP 23.501 v20.2.0 — the document's own text
5.6.17.2 Application Function influence on Handling of Payload Headers
Taught in 12. The connection to a data network (The 5G system architecture, in depth), 5. The connection, and what is promised on it (The 5G system architecture, overview).
An AF may request the Handling of Payload Headers in order to detect, insert, replace, or remove payload headers of PDUs as well as to subscribe to notifications on events related to detection of payload headers of PDUs or related to the actions performed on payload headers of PDUs.
For the Handling of Payload Headers, it is assumed that a service level agreement (SLA) exists between the operator and an application service provider. The mechanism(s) required for detection and actions performed on payload headers (e.g. protocol layer, type of encryption, etc.) is agreed as part of the SLA. The reference(s) to the UPF configuration(s) corresponding to the header detection as well as reference(s) to SMF configuration corresponding to SMF context information are also part of the SLA. Based on the SLA, the AF, either owned by the operator or belonging to the third party, is required to provide such reference(s) in the AF requests for Handling of Payload Headers.
In the non-roaming scenario, the features Handling of Payload Headers, Application Function influence on Service Function Chaining (as defined in clause 5.6.16) and Application Function influence on traffic routing (as defined in clause 5.6.7) can be applied simultaneously.
In the Home Routed roaming scenario, the features Handling of Payload Headers and Application Function influence on Service Function Chaining (as defined in clause 5.6.16) can be applied simultaneously.
The AF requests for Handling of Payload Headers are sent to the PCF via N5 (in the case of requests targeting specific on-going PDU Sessions of individual UE(s), for an AF allowed to interact directly with the 5GC NFs) or via the NEF. The AF requests that target existing or future PDU Sessions of multiple UE(s) or of any UE are sent via the NEF and may target multiple PCF(s), as described in clause 6.3.7.2. The PCF(s) transform(s) the Header Handling Control information provided in the AF requests into Header Handling Control information of the PCC rules that apply to the respective PDU Sessions. When the AF has subscribed to events related to Handling of Payload Headers, the enforcement of a requested action is a Header Handling event, and such event notifications are sent by the UPF(s) either directly to the AF or via an NEF.
When the request is sent via NEF, Nnef_TrafficInfluence service is used. The procedures for AF to request Handling of Payload Headers are described in clause 4.3.6 in TS 23.502 [3].
The AF requests may contain the information as described in the Table 5.6.17.2-1:
Table 5.6.17.2-1: Information elements contained in AF request
| Information Name | Applicable for PCF or NEF (NOTE 1) | Applicable for NEF only | Category |
|---|---|---|---|
| Traffic Description | Defines the target traffic on which to apply handling of headers, represented by the combination of DNN and optionally S-NSSAI and application identifier or traffic filtering information. | The target traffic can be represented by AF-Service-Identifier. | Mandatory |
| Target UE Identifier(s) | Indicates the UE(s) that the request is targeting, i.e. an individual UE, a group of UE represented by Internal Group Identifier(s) (NOTE 2), or any UE accessing the combination of DNN and S-NSSAI. | GPSI can be applied to identify the individual UE, or External Group Identifier can be applied to identify a group of UEs. | Mandatory |
| Spatial Validity Condition | Indicates that the request applies only to the traffic of UE(s) located in the specified location, represented by areas of validity. | The specified location can be represented by geographical area. | Optional |
| Temporal Validity Condition | Time interval(s) when the request applies or duration(s). | N/A | Optional |
| AF transaction identifier | The AF transaction identifier refers to the AF request. | N/A | Mandatory |
| Header Handling Control information | |||
| Header Detection Reference | A reference to a UPF configuration which defines how to detect the protocol or the message in a protocol for which to perform the header handling actions. | N/A | Mandatory |
| Header Detection Support Information(NOTE 3) | Any dynamic information provided by the AF which is required for the detection of the headers and cannot be preconfigured for the Header Detection Reference. | N/A | Optional |
| Header Handling Reporting Endpoint | Notification endpoint, i.e. per notification endpoint a Notification Target Address and a Notification Correlation ID. | N/A | Optional |
| Header Handling Control Reference(NOTE 5) | A reference to a Header Handling Action related information pre-configured in the UPF. | N/A | Optional |
| Header Handling Direction(NOTE 4) | Indicates if the header handling applies to UL or DL direction. | N/A | Optional |
| Header Handling Action(NOTE 4) | Indicates the action to be performed on a specific header field. | N/A | Optional |
| Header Information(NOTE 4) | A reference to a UPF configuration which defines how to identify or build a specific header field for which to perform the header handling action. | N/A | Optional |
| Header Value(NOTE 4) | A string providing the value (or a reference to information to be provided by SMF) of the specific header field. | N/A | Optional |
| Header Handling Condition(NOTE 4) | Indicates the condition for performing the header handling action. | N/A | Optional |
| Header Handling Reporting (NOTE 4) | Indicates whether reporting is requested for the performed Header Handling Action. | N/A | Optional |
| NOTE 1: When the AF request targets existing or future PDU Sessions of multiple UE(s) or of any UE and is sent via the NEF, as described in clause 6.3.7.2, the information is stored in the UDR by the NEF and notified to the PCF by the UDR.NOTE 2: Internal Group ID can only be used by an AF controlled by the operator and only towards PCF.NOTE 3: The NEF, PCF and SMF do not need to understand the Header Detection Support Information.NOTE 4: These parameters are provided together to request a Header Handling Action. Multiple sets of these parameters (and thus multiple header handling actions) can be provided.NOTE 5: If a Header Handling Control Reference is provided, one or more of these parameters (marked by NOTE 4) can be provided to overwrite Header Handling Control information that is pre-configured in the UPF as per the Header Handling Control Reference. Multiple Header Handling Control References can be provided. |
Traffic Description, Target UE identifier(s) and AF transaction identifier are common to all features requested simultaneously in the same AF request, more specifically, Application Function influence on Handling of Payload Headers, Application Function influence on Service Function Chaining (as defined in clause 5.6.16) and/or Application Function influence on traffic routing (as defined in clause 5.6.7). Spatial and Temporary validity conditions are optionally provided for a specific feature.
For each information element mentioned above as part of Header Handling Control Information in the AF request, a detailed description follows:
- Header Detection Reference:
A reference to a UPF configuration which defines how to detect the protocol or the message in a protocol for which to perform the header handling actions (e.g. information about protocol layer, type of encryption, message type etc.).
- Header Detection Support Information:
Header Detection Support Information is not standardised, but it can be interpreted by UPF based on SLA. It is sent transparently by NEF, PCF and SMF to UPF. It includes dynamic information provided by the AF which is required for the detection of the headers and cannot be preconfigured for the Header Detection Reference in UPF.
- Header Handling Reporting Endpoints:
The notification endpoint provided by the AF for the notifications related to the Handling of Payload Headers. For the notification endpoint, a Notification Target Address and a Notification Correlation ID has to be provided.
- Header Handling Direction:
Header Handling Direction indicates to which direction the Header Handling Action applies to. It can have the values uplink (UL) or downlink (DL).
- Header Handling Action:
The action to be performed on a specific header field. One of the following can be requested:
- Detect. It is used to request the detection of a header field that is identified based on the UPF configuration referenced by the Header Information parameter and the information contained in the Header Value parameter, if it is provided.
- Remove. It is used to request the removal of a header field that is identified based on the UPF configuration referenced by the Header Information parameter and the information contained in the Header Value parameter, if it is provided.
- Replace. It is used to request the replacement of information in a header field that is identified based on the UPF configuration referenced by the Header Information parameter. The information to be replaced in the header field is also defined by that UPF configuration. The Header Value contains information that is used for the replacement.
- Insert. It is used to add a header field according to the UPF configuration referenced by the Header Information parameter. The Header Value contains information that is used for the insertion, if it is provided.
When multiple actions are requested on the target traffic, the enforcement of the Header Handling Action is performed in the following order: Detect, Remove, Replace and Insert.
NOTE 1: The execution order is relevant to build a request that has the intended impact on the traffic. For example, a header that is removed cannot be replaced.
- Header Information:
A reference to a UPF configuration which defines how to identify or build a specific header field for which to perform the header handling action.
- Header Value:
A string providing the value (or a reference to information to be provided by SMF) of the specific header field relevant for the action (i.e. to detect in case of actions Detect or Remove and for updating in case of actions Insert or Replace). Header Value may optionally be provided apart from the Replace action for which it is mandatory.
- Header Handling Condition:
This defines how to apply the Header Handling Action. It may have one of the following values: every match or only for the first match.
NOTE 2: In addition, Spatial Validity Condition and Temporary Validity Condition parameters in the request can be used to indicate that the request applies only in certain UE location(s) or during certain time interval(s), respectively.
- Header Handling Reporting:
Indicates whether reporting is requested for the performed Header Handling Action or not. In addition, to reduce signalling, the consumer may provide:
- Reporting suggestion information as described in clause 5.8.2.17.
- One-Time-Report indication, if the reporting of a first occurrence of the action per packet flow is enough.
When reporting is requested for an Action, the AF shall also provide Header Handling Reporting Endpoint.
- Header Handling Control Reference:
A reference to a Header Handling Action related information that is pre-configured in the UPF. This pre-configuration in UPF comprise parameters 4-9. The Header Handling Control Reference can be provided in the AF request instead of providing the parameters of the Header Handling Control Information individually.
NOTE 3: The reference to a Header Handling Control information that is pre-configured in the UPF and the corresponding header handling behaviour has to be agreed as part of the SLA. In a deployment, for simplicity, an operator can choose to set this reference to the same value as the Header Handling Detection Reference.