4.2.6 Npcf_PolicyAuthorization_Subscribe service operation

29.5143GPP5G SystemPolicy Authorization ServiceRelease 18Stage 3TS

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

4.2.6.1 General

The Npcf_PolicyAuthorization_Subscribe service operation enables NF service consumers handling of subscription to events for the existing application session context. Subscription to events shall be created:

– within the application session context establishment procedure by invoking the Npcf_PolicyAuthorization_Create service operation, as described in clause 4.2.2; or

– within the application session context modification procedure by invoking the Npcf_PolicyAuthorization_Update service operation, as described in clause 4.2.3; or

– by invoking the Npcf_PolicyAuthorization_Subscribe service operation for the existing application session context, as described in clause 4.2.6.2.

The following procedures using the Npcf_PolicyAuthorization_Subscribe service operation is supported:

– Handling of subscription to events for the existing application session context.

– Initial subscription to events without provisioning of service information.

– Subscription to usage monitoring of sponsored data connectivity.

– Request of access network information.

– Subscription to notification of signalling path status.

– Subscription to Service Data Flow QoS Monitoring Information.

– Subscription to application detection notifications.

– Subscription to satellite backhaul category changes

4.2.6.2 Handling of subscription to events for the existing application session context

This procedure is used to create a subscription to events for the existing AF application session context bound to the corresponding PDU session or to modify an existing subscription, as defined in 3GPP TS 23.501 [2], 3GPP TS 23.502 [3] and 3GPP TS 23.503 [4].

Figure 4.2.6.2-1 illustrates the creation of events subscription information using HTTP PUT method.

Figure 4.2.6.2-1: Creation of events subscription information using HTTP PUT

Figure 4.2.6.2-2 illustrates the modification of events subscription information using HTTP PUT method.

Figure 4.2.6.2-2: Modification of events subscription information using HTTP PUT

When the NF service consumer decides to create a subscription to one or more events for the existing application session context or to modify an existing subscription previously created by itself at the PCF, the NF service consumer shall invoke the Npcf_PolicyAuthorization_Subscribe service operation by sending the HTTP PUT request to the resource URI representing the "Events Subscription" sub-resource in the PCF, as shown in figure 4.2.6.2-1, step 1 and figure 4.2.6.2-2, step 1. The NF service consumer shall provide in the "EventsSubscReqData" data type of the body of the HTTP PUT request:

– the "events" attribute with the list of events to be subscribed; and

– the "notifUri" attribute that includes the Notification URI to indicate to the PCF where to send the notification of the subscribed events.

NOTE 1: The "notifUri" attribute within the EventsSubscReqData data structure can be modified to request that subsequent notifications are sent to a new NF service consumer.

Upon the reception of the HTTP PUT request from the NF service consumer, the PCF shall decide whether the received HTTP PUT request is accepted.

If the HTTP PUT request from the NF service consumer is rejected, the PCF shall indicate in the HTTP response the cause for the rejection as specified in clause 5.7.

If the feature "ES3XX" is supported, and the PCF determines the received HTTP PUT request needs to be redirected, the PCF shall send an HTTP redirect response as specified in clause 6.10.9 of 3GPP TS 29.500 [5].

If the PCF accepted the HTTP PUT request to create a subscription to events, the PCF shall create the "Events Subscription" sub-resource and shall send the HTTP response message to the NF service consumer as shown in figure 4.2.6.2-1, step 2. The PCF shall include in the "201 Created" response:

– a Location header field that shall contain the URI of the created "Events Subscription" sub-resource i.e. "{apiRoot}/npcf-policyauthorization/v1/app-sessions/{appSessionId}/events-subscription"; and

– a response body with the "EventsSubscPutData" data type, that contains the attributes of the "EventsSubscReqData" data type, representing the created "Events Subscription" sub-resource.

If the PCF determines that one or more of the subscribed events are already met in the PCF, the PCF may also include the attributes of the "EventsNotification" data type within the "EventsSubscPutData" data type to notify about the already met events in the PCF.

If the PCF accepted the HTTP PUT request to modify the events subscription, the PCF shall modify the "Events Subscription" sub-resource and shall send to the NF service consumer:

– the HTTP "204 No Content" response (as shown in figure 4.2.6.2-2, step 2a); or

– the HTTP "200 OK" response (as shown in figure 4.2.6.2-2, step 2b) including in the "EventsSubscPutData" data type the updated representation of the "Events Subscription" sub-resource encoded within the attributes of the "EventsSubscReqData" data type and, if one or more of the updated subscribed events are already met in the PCF, the notification of these events by including the attributes of the "EventsNotification" data type.

The PCF shall include in the "evsNotif" attribute:

– if the NF service consumer subscribed to the "PLMN_CHG" event in the HTTP PUT request, the "event" attribute set to "PLMN_CHG" and the "plmnId" attribute including the PLMN Identifier or the SNPN Identifie if the PCF has previously requested to be updated with this information in the SMF; and

NOTE 2: The SNPN Identifier consists of the PLMN Identifier and the NID.

NOTE 3: Handover between non-equivalent SNPNs, and between SNPN and PLMN is not supported. When the UE is operating in SNPN access mode, the trigger reports changes of equivalent SNPNs.

– if the NF service consumer subscribed to the "ACCESS_TYPE_CHANGE" event in the HTTP PUT request, the "event" attribute set to "ACCESS_TYPE_CHANGE" and:

i. the "accessType" attribute including the access type, and the "ratType" attribute including the RAT type when applicable for the notified access type; and

ii. if the "ATSSS" feature is supported, the "addAccessInfo" attribute with the additional access type information if available, where the access type is encoded in the "accessType" attribute, and the RAT type is encoded in the "ratType" attribute when applicable for the notified access type; and

NOTE 4: For a MA PDU session, if the "ATSSS" feature is not supported by the NF service consumer the PCF includes the "accessType" attribute and the "ratType" attribute with a currently active combination of access type and RAT type (when applicable for the notified access type). When both 3GPP and non-3GPP accesses are available, the PCF includes the information corresponding to the 3GPP access.

iii. the "anGwAddr" attribute including access network gateway address when available,

if the PCF has previously requested to be updated with this information in the SMF.

Based on the received subscription information from the NF service consumer, the PCF may create a subscription to event notifications or may modify the existing subscription to event notifications, for a related PDU session from the SMF, as described in 3GPP TS 29.512 [8].

4.2.6.3 Initial subscription to events without provisioning of service information

The NF service consumer may subscribe with the PCF to events notification without providing service information.

NOTE 1: This service operation is intended to create a resource that enables to handle subscription to events without provisioning service information. For the scenarios where it is known the NF service consumer, after creating a subscription without service information, could require an application session context with the PCF with required service information, the NF service consumer needs to create an Individual Application Session context as described in clause 4.2.2.2.

Figure 4.2.6.3-1 illustrates the initial subscription to events without provisioning of service information.

Figure 4.2.6.3-1: Initial Subscription to events without provisioning of service information

When a NF service consumer establishes an application session context with the PCF to subscribe to events and does not require PCC control for the related media, the NF service consumer shall invoke the Npcf_PolicyAuthorization_Subscribe service operation by sending the HTTP POST request to the resource URI representing the "Application Sessions" collection resource of the PCF, as shown in figure 4.2.6.3-1, step 1.

The NF service consumer shall include in the "ascReqData" attribute of the "AppSessionContext" data type in the payload body of the HTTP POST request:

– either the "ueMac" attribute containing the UE MAC address, or the "ueIpv4" attribute or "ueIpv6" attribute containing the UE IPv4 or the IPv6 address;

– the "notifUri" attribute containing the URI where the PCF shall request to the NF service consumer the deletion of the "Individual Application Session Context" resource"; and

– the "evSubsc" attribute of "EventsSubscReqData" data type to request the notification of certain user plane events. The NF service consumer shall include:

a. the events to subscribe to in the "events" attribute; and

b. the notification URI where to address the notification of the met events within the "notifUri" attribute.

The NF service consumer may provide in the "AppSessionContext" data type the DNN in the "dnn" attribute, SUPI in the "supi" attribute or other information if available.

If the PCF cannot successfully fulfil the received HTTP POST request due to the internal PCF error or due to the error in the HTTP POST request, the PCF shall send the HTTP error response as specified in clause 5.7.

Otherwise, when the PCF receives the HTTP POST request from the NF service consumer, the PCF shall apply session binding as described in 3GPP TS 29.513 [7]. The PCF identifies the PDU session for which the HTTP POST request applies as described in clause 4.2.2.2.

The information required for session binding (UE MAC address, or UE Ipv4 or IPv6 address, DNN, SUPI and other available information, such as S-NSSAI and/or IPv4 address domain identifier) is provisioned in the "Individual Application Session Context" resource. The events subscription is provisioned in the "Events Subscription" sub-resource.

Based on the received subscription information from the NF service consumer, the PCF may create a subscription to event notifications for a related PDU session from the SMF, as described in 3GPP TS 29.512 [8].

If the PCF created the "Events Subscription" sub-resource within the "Individual Application Session Context" resource, the PCF shall send to the NF service consumer a "201 Created" response to the HTTP POST request, as shown in figure 4.2.6.3-1, step 2. The PCF shall include in the "201 Created" response:

– a Location header field; and

– an "AppSessionContext" data type in the payload body.

The Location header field shall contain the URI of the created events subscription sub-resource i.e. "{apiRoot}/npcf-policyauthorization/v1/app-sessions/{appSessionId}/events-subscription".

The "AppSessionContext" data type payload body shall contain the representation of the created "Individual Application Session Context" resource and "Events Subscription" sub-resource.

The PCF shall include in the "evsNotif" attribute:

– if the NF service consumer subscribed to the event "PLMN_CHG" in the HTTP POST request, the "event" attribute set to "PLMN_CHG" and the "plmnId" attribute including the PLMN Identifier or the SNPN Identifier if the PCF has previously requested to be updated with this information in the SMF;

NOTE 2: The SNPN Identifier consists of the PLMN Identifier and the NID.

NOTE 3: Handover between non-equivalent SNPNs, and between SNPN and PLMN is not supported. When the UE is operating in SNPN access mode, the trigger reports changes of equivalent SNPNs.

– if the NF service consumer subscribed to the event "ACCESS_TYPE_CHANGE" in the HTTP POST request, the "event" attribute set to "ACCESS_TYPE_CHANGE" and:

i. the "accessType" attribute including the access type, and the "ratType" attribute including the RAT type when applicable for the notified access type; and

NOTE 4: For a MA PDU session, if the "ATSSS" feature is not supported by the NF service consumer the PCF includes the "accessType" attribute and the "ratType" attribute with a currently active combination of access type and RAT type (if applicable for the notified access type). When both 3GPP and non-3GPP accesses are available, the PCF includes the information corresponding to the 3GPP access.

iii. the "anGwAddress" attribute including access network gateway address when available,

if the PCF has previously requested to be updated with this information in the SMF; and

– if the "IMS_SBI" feature is supported and if the NF service consumer subscribed to the event "CHARGING_CORRELATION" in the HTTP POST request, the "event" attribute set to "CHARGING_CORRELATION" and may include the "anChargIds" attribute containing the access network charging identifier(s) and the "anChargAddr" attribute containing the access network charging address.

NOTE 5: Due to the resource structure, as result of the Npcf_PolicyAuthorization_Subscribe service operation using POST methods, the PCF creates an Individual Application Session context resource which can only be deleted via Npcf_PolicyAuthorization_Delete service operation.

4.2.6.4 Subscription to usage monitoring of sponsored data connectivity

This procedure is used by a NF service consumer to subscribe with the PCF to usage monitoring of sponsored data connectivity or to provide updated usage thresholds for the existing application session context, when the "Sponsored Connectivity" feature is supported.

The NF service consumer shall include in the HTTP PUT request message described in clause 4.2.6.2 the "EventsSubscReqData" data type, that shall contain:

– the "events" attribute with a new entry of the "AfEventSubscription" data type with the "event" attribute set to "USAGE_REPORT"; and

– the "usgThres" attribute with the usage thresholds to apply.

The PCF shall reply to the NF service consumer as described in clause 4.2.6.2.

4.2.6.5 Void

4.2.6.6 Request of access network information

This procedure is used by a NF service consumer to request the PCF to report the access network information (i.e. user location and/or user timezone information) without providing service information when the "NetLoc" feature is supported.

The NF service consumer can request access network information without providing service information:

– at initial subscription to events, using the HTTP POST request message as described in clause 4.2.6.3; and

– at modification of the subscription to events, using the HTTP PUT request message as described in clause 4.2.6.2.

The NF service consumer shall include in the HTTP request message:

– an entry of the "AfEventSubscription" data type in the "events" attribute with:

a) the "event" attribute set to the value "ANI_REPORT"; and

b) the "notifMethod" attribute set to the value "ONE_TIME"; and

– the "reqAnis" attribute, with the required access network information, i.e. user location and/or user time zone information).

When the PCF determines that the access network does not support the access network information reporting because the SMF does not support the NetLoc feature, the PCF shall respond to the NF service consumer including in the "EventsNotification" data type the "noNetLocSupp" attribute set to "ANR_NOT_SUPPORTED" value. Otherwise, the PCF shall immediately configure the SMF to provide such access information, as specified in 3GPP TS 29.512 [8].

The PCF shall reply to the NF service consumer with the HTTP POST response as described in clause 4.2.6.3 and with the HTTP PUT response as described in clause 4.2.6.2.

4.2.6.7 Subscription to notification of signalling path status

When the feature "IMS_SBI" is supported, this procedure is used by a NF service consumer to subscribe to notifications of the status of the AF signalling transmission path.

The NF service consumer shall create a new "Individual Application Session Context" resource with the PCF for the AF signalling using the Npcf_PolicyAuthorization_Create service operation.

The NF service consumer shall provide:

– the IP address (IPv4 or IPv6) of the UE in the "ueIpv4" or "ueIpv6" attribute;

– within the "evSubsc" attribute, the "event" attribute set to "FAILED_RESOURCES_ALLOCATION"; and

– a media component within the "medComponents" attribute including:

– the "medCompN" attribute set to "0"; and

– a single media subcomponent within the "medSubComps" attribute with:

– the "flowUsage" attribute set to the value "AF_SIGNALLING"; and

– if the procedures for NF service consumer provisioning of AF signalling flow information do not apply, the "fNum" attribute set to "0".

When the "fNum" attribute is set to "0", the rest of attributes within the related media component and media subcomponent shall not be used.

The PCF shall perform session binding as described in 3GPP TS 29.513 [7] and shall reply to the NF service consumer as described in clause 4.2.6.3.

PCC rules related to AF signalling IP flows should be provisioned to SMF using the corresponding procedures specified at 3GPP TS 29.512 [8] at an earlier stage (e.g. typically at the establishment of the QoS flow dedicated for AF signalling IP flows). The PCF may install the corresponding dynamic PCC rules for the AF signalling IP flows if none has been installed before.

NOTE 1: Well-known ports (e.g. 3GPP TS 24.229 [32] for SIP) or wildcard ports can be used by PCF to derive the dynamic PCC for the AF signalling IP flows.

If the "Individual Application Session Context" resource is only used for subscription to notification of AF signalling path status, the NF service consumer may cancel the subscription to notifications of the status of the AF signalling transmission path removing the resource as described in clause 4.2.4.2.

NOTE 2: The "Individual Application Session Context" resource created for the AF signalling can also be used when the NF service consumer requests notifications of access type change, access network information for SMS over IP and/or when the NF service consumer provisions AF Signalling Flow Information.

4.2.6.8 Subscription to Service Data Flow QoS Monitoring Information

This procedure is used by NF service consumer to subscribe and/or modify the PCF subscription for notification about packet delay between UPF and RAN.

The NF service consumer shall include in the HTTP PUT request message described in clause 4.2.6.2 the "EventsSubscReqData" data type, that shall contain:

– to create a subscription to notifications of QoS monitoring report:

a) shall include the "events" array with an array that contains a new entry per requested notification method with the "event" attribute set to "QOS_MONITORING", and notification related information as described in clause 4.2.2.23;

b) when the "notifMethod" of the new entry is "EVENT_DETECTION", shall include a "qosMon" attribute with the QoS monitoring information as described in clause 4.2.2.23;

c) shall include the new requested QoS monitoring parameter(s) to be measured (i.e. DL, UL and/or round trip packet delay) within the "reqQosMonParams" attribute; and

d) may include the notification correlation identifier assigned by the AF within the "notifCorreId" attribute;

e) if the feature "ExposureToEAS" is supported, may include the "directNotifInd" attribute set to true to indicate the direct event notification of QoS Monitoring data from the UPF.

– to remove a subscription to QoS monitoring information:

a) shall include the "events" array containing an array that shall omit the corresponding entry with the "event" attribute value "QOS_MONITORING"; and

b) when the "notifMethod" of the removed entry is "EVENT_DETECTION", it shall omit the "qosMon" attribute;

c) shall omit the "reqQosMonParams";

d) if the feature "ExposureToEAS" is supported, shall omit the "directNotifInd" attribute;

The NF service consumer shall include other events related information that shall remain unchanged.

As result of this action, the PCF shall set the appropriate subscription to QoS monitoring information for the corresponding active PCC rule(s) as described in 3GPP TS 29.512 [8].

The PCF shall reply to the NF service consumer as described in clause 4.2.6.2.

4.2.6.9 Subscription to application detection notification

This procedure is used by a NF service consumer to request the PCF the subscription to application (e.g. start, stop) detection notifications, if the "ApplicationDetectionEvents" feature is supported.

The NF service consumer can request the subscription to notification of application detection events without providing service information:

– at initial subscription to events, using the HTTP POST request message as described in clause 4.2.6.3; and

– at modification of the subscription to events, using the HTTP PUT request message as described in clause 4.2.6.2.

The NF service consumer shall include:

– To subscribe to notifications about the detection of the start/stop of one or more application’s traffic the "evSubsc" attribute within the POST request as described in clause 4.2.6.3, with:

a. the "events" array, including an event with the "event" attribute value set to "APP_DETECTION"; and

b. the "afAppIds" attribute, with the list of AF application identifier(s) that refer to the applications’ traffic to detect.

– To modify the subscription to notifications of application’s traffic detection the "EventsSubscReqData" data type within the PUT request as described in clause 4.2.6.2, including an event with the "event" attribute value set to "APP_DETECTION" and an updated list of AF application identifiers within the "afAppIds" attribute.

– To remove the subscription to notifications about the start and stop of the applications traffic, an "events" array within the PUT request as described in clause 4.2.6.2, without including any event with the "event" attribute value "APP_DETECTION" and omitting the "afAppIds" attribute.

The PCF shall reply to the NF service consumer with the HTTP POST response as described in clause 4.2.6.3 and with the HTTP PUT response as described in clause 4.2.6.2.

The PCF shall set the appropriate subscription to Application Detection for the corresponding PCC rule(s) as described in 3GPP TS 29.512 [8].

In this release of the specification application detection applies only to the application(s) with IP traffic.

4.2.6.10 Subscription to satellite backhaul category changes

When the feature "SatelliteBackhaul" is supported, this procedure is used by NF service consumer to subscribe and/or modify the PCF subscription to receive a notification when the satellite backhaul category changes and when the backhaul category changes between satellite backhaul and non-satellite backhaul.

The NF service consumer shall include in the HTTP PUT request message described in clause 4.2.6.2 the "EventsSubscReqData" data type, or in the HTTP POST request message described in clause 4.2.6.3 the "evSubsc" attribute, that shall contain the "events" array, with a new entry with the "event" attribute set to "SAT_CATEGORY_CHG" to indicate the creation of a subscription to backhaul category changes.

The NF service consumer shall include other events related information that shall remain unchanged.

As result of this action, the PCF shall set the appropriate subscription to satellite backhaul changes for the PDU session as described in in 3GPP TS 29.512 [8].

The PCF shall reply to the NF service consumer as described in clause 4.2.6.2 or in clause 4.2.6.3. The PCF shall include the "evsNotif" attribute with an entry in the "evNotifs" array with the "event" attribute set to "SAT_CATEGORY_CHG" and the "satBackhaulCategory" attribute including the satellite backhaul category or the indication of non-satellite backhaul if the PCF has previously subscribed with the SMF to changes in this information.