Content for TS 29.502 Word version: 18.5.0

1… 5… 5.2.2… 5.2.2.2.4… 5.2.2.3… 5.2.2.3.2… 5.2.2.3.3… 5.2.2.3.6… 5.2.2.3.8… 5.2.2.3.10… 5.2.2.3.17… 5.2.2.3.23… 5.2.2.4… 5.2.2.8… 5.2.2.8.2… 5.2.2.8.2.7… 5.2.2.8.2.12… 5.2.2.8.2.20… 5.2.2.8.3… 5.2.2.8.3.6… 5.2.2.9… 5.2.3… 6… 6.1.2… 6.1.3… 6.1.3.3… 6.1.3.5… 6.1.3.6… 6.1.3.7… 6.1.4… 6.1.6… 6.1.6.2… 6.1.6.2.5… 6.1.6.2.11… 6.1.6.2.18… 6.1.6.2.27… 6.1.6.2.40… 6.1.6.2.54… 6.1.6.2.65… 6.1.6.3… 6.1.6.4… 6.1.7… A… B… C…

6.1.7 Error Handling 6.1.7.1 General 6.1.7.2 Protocol Errors 6.1.7.3 Application Errors 6.1.8 Feature Negotiation 6.1.9 Security 6.1.10 HTTP redirection
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6.1.7 Error Handling p. 279

6.1.7.1 General p. 279

HTTP error handling shall be supported as specified in clause 5.2.4 of TS 29.500.

The Cause codes mapping performed by AMF between the following HTTP responses returned by the SMF services to the AMF and the 5GMM related values is specified in clause 4.3.2 of TS 29.524.

In order to enable the AMF to Figure out whether a request (e.g. PDU session establishment request) fails at the V-SMF/I-SMF or at the H-SMF/SMF for a HR PDU session or a PDU session with an I-SMF:

a V-SMF/I-SMF that returns an HTTP error response to the AMF that was originated by the H-SMF/SMF shall include the remoteError attribute set to "true" in the ProblemDetails information in the HTTP error response;
a V-SMF/I-SMF that originates an error to the AMF may include the remoteError attribute set to "false" in the ProblemDetails information in the HTTP error response.

For a HR PDU session or a PDU session with an I-SMF, if the V-SMF or I-SMF needs to reject the request from the AMF or the H-SMF/SMF because the H-SMF/SMF or the AMF is not reachable respectively (even after retrying alternative endpoint addresses e.g. according to the Binding Indication when available), the V-SMF or I-SMF shall send a 504 Gateway Timeout response including a problemDetails data structure with the cause attribute set to "PEER_NOT_RESPONDING" and with the remoteError attribute set to "false".

6.1.7.2 Protocol Errors p. 279

Protocol errors handling shall be supported as specified in clause 5.2.7 of TS 29.500.

6.1.7.3 Application Errors p. 279

The common application errors defined in Table 5.2.7.2-1 of TS 29.500 may be used for the Nsmf_PDUSession service.

The following application errors listed in Table 6.1.7.3-1 are specific to the Nsmf_PDUSession service.

Table 6.1.7.3-1: Application errors

Application Error	HTTP status code	Description
N1_SM_ERROR	403 Forbidden	This indicates that an error, other than those listed in this table, was detected when processing the N1 SM information received in the request, e.g. N1 SM protocol error, or a PDU session establishment is rejected due to Operator Determined Barring.
N2_SM_ERROR	403 Forbidden	This indicates that an error, other than those listed in this table, was detected when processing the N2 SM information received in the request, e.g. N2 SM protocol error.
SNSSAI_DENIED	403 Forbidden	The subscriber does not have the necessary subscription to access the SNSSAI.
DNN_DENIED	403 Forbidden	The subscriber does not have the necessary subscription to access the DNN.
PDUTYPE_DENIED	403 Forbidden	The subscriber does not have the necessary subscription for the requested PDU session type.
SSC_DENIED	403 Forbidden	The subscriber does not have the necessary subscription for the requested SSC mode.
SUBSCRIPTION_DENIED	403 Forbidden	This indicates an error, other than those listed in this table, due to lack of necessary subscription to serve the UE request.
DNN_NOT_SUPPORTED	403 Forbidden	The DNN is not supported by the SMF.
PDUTYPE_NOT_SUPPORTED	403 Forbidden	The requested PDU session type is not supported by the SMF for the PDN corresponding to the DNN.
SSC_NOT_SUPPORTED	403 Forbidden	The requested SSC mode is not supported by the SMF for the PDN corresponding to the DNN.
HOME_ROUTED_ROAMING_REQUIRED	403 Forbidden	It is used in LBO roaming, if the V-SMF is not able to process some part of the N1 SM information that requires Home Routed Roaming.
OUT_OF_LADN_SERVICE_AREA	403 Forbidden	The PDU session corresponds to a LADN and the UE is outside of the LADN Service Area.
N2_SM_ERROR	403 Forbidden	This indicates that an error, other than those listed in this table, was detected when processing the N2 SM information received in the request, e.g. N2 SM protocol error.
PRIORITIZED_SERVICES_ONLY	403 Forbidden	The SMF was notified that the UE is reachable only for regulatory prioritized service and the PDU Session to be activated is not for a regulatory prioritized service.
PDU_SESSION_ANCHOR_CHANGE	403 Forbidden	The SMF decided to change the PDU Session Anchor for the PDU Session.
TARGET_MME_CAPABILITY	403 Forbidden	A request to retrieve an SM context is rejected due to the target MME not capable to support the PDU session.
NO_EPS_5GS_CONTINUITY	403 Forbidden	It is used during an EPS to 5GS Idle mode mobility or handover, if the PDU session does not support seamless session continuity to 5GS.
UNABLE_TO_PAGE_UE	403 Forbidden	The request is rejected due to a temporarily inability to page the UE.
UE_NOT_RESPONDING	403 Forbidden	The UE did not respond to the request initiated by the network, e.g. paging.
REJECTED_BY_UE	403 Forbidden	The request is rejected by the UE.
REJECTED_DUE_VPLMN_POLICY	403 Forbidden	The request is rejected due to VPLMN operator policy.
HO_TAU_IN_PROGRESS	403 Forbidden	The request is rejected temporarily due to a mobilty procedure in progress.
INTEGRITY_PROTECTED_MDR_NOT_ACCEPTABLE	403 Forbidden	The integrity protected maximum data rate value provided by the UE is not acceptable for the PDU session based on local policy at the SMF. This error is applicable when the UP Security Policy for the PDU Session is determined to have Integrity Protection set to "Required". An NF service consumer that receives this error cause may use it for maintaining KPIs.
EBI_EXHAUSTED	403 Forbidden	The allocation of EPS Bearer ID failed due to exhaustion of EBI as the maximum number of EBIs has already been allocated to the UE.
EBI_REJECTED_LOCAL_POLICY	403 Forbidden	The allocation of EPS Bearer ID was rejected due to local policy in the Serving PLMN.
EBI_REJECTED_NO_N26	403 Forbidden	The allocation of EPS Bearer ID was rejected when the AMF is in a serving PLMN that does not support 5GS-EPS interworking procedures with N26 interface.
DEFAULT_EPS_BEARER_INACTIVE	403 Forbidden	It is used during EPS to 5GS mobility if the default EPS bearer context of the PDU session is reported as inactive by the UE in the epsBearerCtxStatus attribute.
HANDOVER_RESOURCE_ALLOCATION_FAILURE	403 Forbidden	It is used during a N2 handover preparation or an EPS to 5GS handover preparation, if no resource is allocated by the target NG-RAN for the PDU session.
LATE_OVERLAPPING_REQUEST	403 Forbidden	The request is rejected because it collides with an existing SM context or PDU session context with a more recent origination timestamp (see clause 5.2.3.3).
DEFAULT_EBI_NOT_TRANSFERRED	403 Forbidden	It is used during 5GS to EPS mobility if the EBI of the default EPS bearer is included in the notToTransferEbiList attribute.
NOT_SUPPORTED_WITH_ISMF	403 Forbidden	The request is rejected due to a requested functionality that is not supported for a PDU session with an I-SMF/V-SMF.
SERVICE_NOT_AUTHORIZED_BY_NEXT_HOP	403 Forbidden	The SMF is not authorized to access service provided by next hop NF producer, e.g. H-SMF or SMF or old I-SMF or old V-SMF.
NO_DATA_FORWARDING	403 Forbidden	The request to setup data forwarding tunnels is rejected because none of the EPS bearer contexts received in the request body contains an F-TEID for DL data forwarding.
S_NSSAI_UNAVAILABLE_DUE_TO_NSAC	403 Forbidden	The NSACF has returned error for the requested S-NSSAI and hence the PDU Session cannot be transferred from non-3gpp to 3gpp.
EXCEEDED_UE_SLICE_DATA_RATE	403 Forbidden	The request is rejected due to the maximum bit rate per S-NSSAI per UE is exceeded, when the SMF receives the same application error from the PCF.
EXCEEDED_SLICE_DATA_RATE	403 Forbidden	The request is rejected due to the maximum bit rate per S-NSSAI is exceeded, when the SMF receives the same application error from the PCF.
CONTEXT_NOT_FOUND	404 Not Found	It is used when no context corresponding to the request exists in the SMF.
HIGHER_PRIORITY_REQUEST_ONGOING	409 Conflict	The request is rejected temporarily due to procedure for higher priority session in progress.
UE_IN_CM_IDLE_STATE	409 Conflict	The request is rejected due to the UE being in CM-IDLE state for the PDU session associated to non-3GPP access.
INSUFFICIENT_RESOURCES_SLICE	500 Internal Server Error	The request cannot be provided due to insufficient resources for the specific slice.
INSUFFICIENT_RESOURCES_SLICE_DNN	500 Internal Server Error	The request cannot be provided due to insufficient resources for the specific slice and DNN.
DNN_CONGESTION	503 Service Unavailable	The SMF has detected congestion for the requested DNN and performs overload control for that DNN which does not allow the PDU session to be established.
S_NSSAI_CONGESTION	503 Service Unavailable	During PDU session establishment, the SMF has detected congestion for the requested S-NSSAI (including the congestion due to NSAC failure) and performs overload control for that S-NSSAI which does not allow the PDU session to be established. During handover between 3GPP access and non-3GPP access, the SMF has detected congestion for the requested S-NSSAI on the target access (e.g., due to NSAC) and performs overload control for that S-NSSAI on the target access which does not allow the PDU session to be handover to the target access.
PEER_NOT_RESPONDING	504 Gateway Timeout	No response is received from a remote peer, or the remote peer is known to be not reachable, e.g. to indicate that no response has been received from the H-SMF for a HR PDU session or the SMF for a PDU session with I-SMF.
NETWORK_FAILURE	504 Gateway Timeout	The request is rejected due to a network problem.
UPF_NOT_RESPONDING	504 Gateway Timeout	The request is rejected due to no response received from the UPF.
UE_NOT_REACHABLE	504 Gateway Timeout	The UE is not reachable for service.

6.1.8 Feature Negotiation p. 283

The feature negotiation mechanism specified in clause 6.6 of TS 29.500 shall be used to negotiate the optional features applicable between the SMF and the NF Service Consumer, for the Nsmf_PDUSession service, if any.

The NF Service Consumer shall indicate the optional features it supports for the Nsmf_PDUSession service, if any, by including the supportedFeatures attribute in the HTTP POST request when requesting the SMF to create an SM context or a PDU session resource. In scenarios with a change of NF Service Consumer (e.g. change of AMF, V-SMF or I-SMF change), the new NF Service Consumer shall indicate the optional features it supports for the Nsmf_PDUSession service, if any, by including the supportedFeatures attribute in the HTTP POST request when requesting the SMF to update an SM context or a PDU session resource to change the NF Service Consumer.

The SMF shall determine the supported features for the created SM context or PDU session resource, or for the updated SM context or PDU session resource in scenarios with a change of NF Service Consumer, as specified in clause 6.6 of TS 29.500 and shall indicate the supported features by including the supportedFeatures attribute in the representation of the SM context or PDU session resource it returns in the HTTP response confirming the creation or the modification of the resource.

The syntax of the supportedFeatures attribute is defined in clause 5.2.2 of TS 29.571.

The following features are defined for the Nsmf_PDUSession service.

Table 6.1.8-1: Features of supportedFeatures attribute used by Nsmf_PDUSession service

Feature Number	Feature	M/O	Description
1	CIOT	O	Cellular IoT Support of this feature implies the support of all the CIoT features specified in clause 5.31 of TS 23.501, including in particular corresponding SMF PDUSession service's extensions to support: NB-IoT and LTE-M RAT types; Control Plane CIoT 5GS Optimisation; Rate control of user data; Idle mode mobility with data forwarding between EPS and 5GS using N26 interface. The SMF shall indicate its support of this feature in supportedFeatures attribute in its profile registered in NRF. A NF service consumer (e.g. AMF) shall only select SMF(s) that supports this feature for PDU sessions with Control Plane CIoT 5GS Optimisation enabled.
2	MAPDU	O	Multi-Access PDU Session An SMF that supports this feature shall support the procedures specified inTS 23.501 and TS 23.502 related to Access Traffic Steering, Switching and Splitting.
3	DTSSA	O	Deployments Topologies with specific SMF Service Areas A NF Service Consumer and an SMF that support this feature shall support the procedures specified in clause 5.34 of TS 23.501 and in clause 4.23 of TS 23.502.
4	CARPT	O	SMF derived CN Assisted RAN parameters Tuning. A NF Service Consumer (e.g. AMF) and an SMF that support this feature shall support exchanging SMF derived CN assisted RAN parameters in Notify SM Context Status service operation (see clause 5.2.2.5.1).
5	CTXTR	O	This feature bit indicates whether the NF Service Consumer (e.g. AMF) and SMF supports Network Function/NF Service Context Transfer Procedures specified in clause 4.26 of TS 23.502. The SMF shall only trigger these context transfer procedures if the NF Service Consumer has indicated support of this feature.
6	VQOS	O	VPLMN QoS An SMF that supports this feature shall support: the handling of QoS constraints from the VPLMN during a HR PDU session establishment as specified in clause 4.3.2.2.2 of TS 23.502; and QoS modification requests initiated by the VPLMN, as specified in clause 4.3.3.3 of TS 23.502.
7	HOFAIL	M	This feature bit indicates whether the NF Service Consumer (e.g. AMF, V-SMF, I-SMF) and SMF supports the Notify (SM Context) Status procedure to indicate a handover failure with the Resource Status set to "UPDATED" between 3GPP access and non-3GPP access as specified in clauses 5.2.2.5.1 and 5.2.2.10.1. The SMF shall only trigger such a resource status notify procedure if the NF Service Consumer has indicated support of this feature.
8	ES3XX	M	Extended Support of HTTP 307/308 redirection An NF Service Consumer (e.g. AMF, V-SMF, I-SMF) that supports this feature shall support handling of HTTP 307/308 redirection for any service operation of the PDUSession service. An NF Service Consumer that does not support this feature does only support HTTP redirection as specified for 3GPP Release 15.
9	DCE2ER	O	Dual Connectivity based end to end Redundant User Plane Paths An NF service consumer (e.g. I-SMF) and SMF that supports this feature shall support the procedures specified in clause 5.33.2.1 of TS 23.501.
10	AASN	M	This feature bit indicates whether the NF Service Consumer (e.g. AMF) and the SMF support the Notify SM Context Status procedure to indicate that the PDU session is established towards an alternative anchor SMF, as specified in clause 5.2.2.5.1. The SMF shall only trigger such a Notify SM Context Status procedure if the NF Service Consumer has indicated support of this feature.
11	EnEDGE	O	Enhancement of Edge Computing in 5G Core network A NF Service Consumer and an SMF that support this feature shall support to signal the target DNAI in Notify (SM Context) Status and Create SM Context service operations, support to signal the URI of the SM Context resource in Notify SM Context Status, Create SM Context and create service operations / signal the URI of the PDU Session resource in Notify (SM Context) Status, Create SM Context and create service operations to retrieve the AF Coordination Information, as specified in TS 23.501, TS 23.502 and TS 23.548.
12	SCPBU	O	Simultaneous Change of PSA and BP or UL CL This feature bit indicates whether the NF Service Consumer (e.g. I-SMF) and the SMF support the n4InfoExt3 IE included in VsmfUpdateData, VsmfUpdatedData or VsmfUpdateError to support the simultaneous change of PSA and BP or UL CL controlled by I-SMF. The SMF shall only include the n4InfoExt3 IE in VsmfUpdateData if the NF Service Consumer has indicated support of this feature.
13	ENPN	O	Enhanced support of Non-Public Networks Support of this feature implies the support of the Remote Provisioning of UEs in Onboarding Network procedures, as specified in clause 5.30.2.10.4 of TS 23.501 and clause 4.3.2.2.1 of TS 23.502. The SMF shall indicate its support of this feature in supportedFeatures attribute in its profile registered in NRF. A NF service consumer (e.g. AMF) shall select SMF(s) that supports this feature to setup PDU sessions for Remote Provisioning of UEs in Onboarding Network.
14	SPAE	O	SM Policy Association Events This feature bit indicates whether the NF Service Consumer (e.g. AMF) and the SMF supports the SM Policy Association establishment and termination event notification information handling, i.e. whereby the PCF for UE subscribes to SM Policy Association events to the PCF for SM Policy via the AMF and SMF, as specified in clause 4.3.2.2.1 and clause 4.3.3.2 of TS 23.502.
15	5GSAT	O	This feature bit indicates whether the NF Service Consumer (e.g. AMF, V-SMF, I-SMF) and SMF support the reporting of satellite backhaul information, as specified in clause 5.43.4 of TS 23.501.
16	UPIPE	O	User Plane Integrity Protection with EPS An NF service consumer (e.g. AMF) and SMF that supports this feature shall support the User Plane Integrity Protection with EPS specified in clauses 4.11.1 and 4.11.5.3 of TS 23.502.
17	BIUMR	O	This feature bit indicates whether the NF Service Consumer (e.g. AMF, V-SMF, I-SMF) and SMF supports Binding Indication Update for multiple resource contexts specified in clauses 6.12.1 and 5.2.3.2.6 of TS 29.500.
18	ACSCR	O	Absence of smfUri and hSmfUri attributes in Create SM Context Request for procedures with I-SMF/V-SMF insertion/change other than PDU session establishment and EPS to 5GS mobility procedures. This feature bit indicates that the NF Service Consumer (e.g. AMF) supports not including, and the I-SMF/V-SMF supports not receiving, the smfUri and hSmfUri attributes in the Create SM Context request in procedures with I-SMF/V-SMF insertion/change other than PDU session establishment and EPS to 5GS mobility procedures. An NF Service Consumer and I-SMF/V-SMF complying with this release of the specification shall support this feature if the DTSSA feature is supported. The support of this feature may remove the need for the AMF to fetch the smfUri or hsmfUri from the NRF where the anchor SMF profile is registered, e.g. enable the AMF to skip an inter-PLMN NF Discovery procedure towards the HPLMN during a V-SMF insertion/change when the AMF can determine by other means (e.g. using the anchorSmfSupportedFeatures attribute in PDU session context received over N14) whether the HPLMN supports the DTSSA feature, and accordingly, to fasten the execution of mobility (e.g. handover) scenarios.
19	PSETR	O	This feature bit indicates that the SMF is able to (re)select an alternative peer SMF (when available) when it detects the peer SMF has failed. See also clause 6.8 of TS 23.527. An SMF implementation (complying with this release of the specification) should support the PSETR feature (i.e. support reselecting a peer SMF service instance when the peer SMF fails).
20	DLSET	O	This feature bit indicates that the PDU session resources served by the SMF are not exclusively bound to a SMF service instance, i.e. they are shared by multiple SMF service instances. See also clause 6.8 in TS 23.527.
21	N9FSC	O	N9 Forwarding between Branching Points or UL CLs controlled by the same or different I-SMFs for EAS Session Continuity. An NF Service Consumer and I-SMF/SMF that support this feature shall support the procedures specified in clauses 4.23.9.4 and 4.23.9.5 of TS 23.502 related to the N9 forwarding tunnel establishment between Branching Points or UL CLs controlled by the same or different I-SMFs to support EAS session continuity.
22	DTSSA-Ext1	O	This feature bit indicates that the full list of DNAIs of interest for PDU session, including DNAIs that may not be supported by the I-SMF and excluding the ones supported by the anchor SMF, can be provisioned by the anchor SMF or handled by the I-SMF, which enables the (target) I-SMF to receive such information earlier during an I-SMF insertion or change procedures, so that the I-SMF can decide to insert UL CL/BP and/or a local PSA earlier to save some signalling transactions.
23	5GSATB	O	This feature bit indicates whether the NF Service Consumer (e.g. AMF) is aware that the UE is accessing over a gNB using GEO satellite backhaul and GEO Satellite ID needs to be updated at the SMF (see clause 5.43.2 of TS 23.501.
24	HR-SBO	O	Home Routed Session BreakOut An NF service consumer (e.g. AMF and V-SMF) and SMF that supports this feature shall support local traffic routing in VPLMN for HR-SBO specified in clause 6.7 of TS 23.548.
25	N3GPS	O	Non-3GPP Access Path Switching An SMF or NF service consumer that supports this feature shall support the procedures specified in TS 23.501 and TS 23.502 related to non-3GPP access path switching while maintaining two N2 connections for non-3GPP access.
26	NSRP	O	Network Slice Replacement An NF service consumer (e.g., AMF, V-SMF or I-SMF) and SMF that supports this feature shall support network slice replacement as specified in clause 5.15.19 of TS 23.501.
27	UPCSMT	O	User Plane Connection Suspend State and MT handling This feature bit indicates whether the SMF supports the user plane connection suspend state for a UE entering RRC_Suspend or RRC_Inactive with long eDRX mode and to invoke Namf_MT EnableUEReachability service operation upon receiving subsequent DL Data Notification from the UPF.
28	PSER	O	PDU Session Establishment Rejection A SMF which support this feature shall allow the NF service consumer (i.e. the AMF) to indicate in the Create SM Context request that the PDU session establishment shall be rejected and shall reject the PDU session establishment according to the specific rejection cause received from the NF Service Consumer.
29	SCID	M	String based Charging Identifier A H-SMF shall indicate support of this feature when the SMF, the PCF and the CHF in the HPLMN all support handing of String based Charging Identifier, as specified in TS 32.255. A V-SMF shall indicate support of this feature when the SMF and the CHF in the VPLMN both support handing of String based Charging Identifier, as specified in TS 32.255.
Feature number: The order number of the feature within the supportedFeatures attribute (starting with 1). Feature: A short name that can be used to refer to the bit and to the feature. M/O: Defines if the implementation of the feature is mandatory ("M") or optional ("O"). Description: A clear textual description of the feature.

6.1.9 Security p. 288

As indicated in TS 33.501 and TS 29.500, the access to the Nsmf_PDUSession API may be authorized by means of the OAuth2 protocol (see RFC 6749 [18]), based on local configuration, using the "Client Credentials" authorization grant, where the NRF (see TS 29.510) plays the role of the authorization server.

If OAuth2 authorization is used, an NF Service Consumer, prior to consuming services offered by the Nsmf_PDUSession API, shall obtain a "token" from the authorization server, by invoking the Access Token Request service, as described in clause 5.4.2.2 of TS 29.510.

The Nsmf_PDUSession API defines a single scope "nsmf-pdusession" for the entire service, and it does not define any additional scopes at resource and operation level.

6.1.10 HTTP redirection |R16| p. 288

An HTTP request may be redirected to a different SMF service instance, within the same SMF or a different SMF of an SMF set, e.g. when an SMF service instance is part of an SMF (service) set or when using indirect communications (see TS 29.500). See also the ES3XX feature in clause 6.1.8.

An SCP that reselects a different SMF producer instance will return the NF Instance ID of the new SMF producer instance in the 3gpp-Sbi-Producer-Id header, as specified in clause 6.10.3.4 of TS 29.500.

If an SMF within an SMF set redirects a service request to a different SMF of the set using an 307 Temporary Redirect or 308 Permanent Redirect status code, the identity of the new SMF towards which the service request is redirected shall be indicated in the 3gpp-Sbi-Target-Nf-Id header of the 307 Temporary Redirect or 308 Permanent Redirect response as specified in clause 6.10.9.1 of TS 29.500.

For a HR PDU session or a PDU session with an I-SMF, the V-SMF or I-SMF shall update the AMF upon detecting a change of the H-SMF or SMF within the SMF set, by sending an SM context status notification with the resourceStatus set to "UPDATED", the cause in statusInfo set to "CHANGED_ANCHOR_SMF" and with the new H-SMF or SMF identity (see clause 5.2.2.5.1).