Content for TR 29.891 Word version: 16.0.0
2 References
3 Definitions, symbols and abbreviations
4 Architecture and Requirements
5 Protocol and procedures for User Plane interfaces
6 Protocols, procedures and services for Control Plane interfaces
6.1 General
6.2 Service Based Architecture
6.4 Session Management Function Procedures and Services
6.5 Access and Mobility Management Function Procedures and Services
6.6 Authentication Server Function Procedures and Services
6.7 Unified Data Management Services and Operations
6.8 Network Function Service Registration, Discovery and Selection
6.9 Unstructured Data Storage Function Procedures and Services
6.10 Structured Data Storage Function Procedures and Services
6.12 Network Slice Selection Function Service and Procedures
2 References p. 12
3 Definitions, symbols and abbreviations p. 15
3.1 Definitions p. 15
3.2 Abbreviations p. 15
4 Architecture and Requirements p. 16
4.1 Reference Architecture p. 16
4.2 General Requirements p. 18
5 Protocol and procedures for User Plane interfaces p. 18
5.1 Requirements p. 18
5.2 Solution and Protocol Selection p. 21
5.2.1 Solution 1 - N3 and N9 based on GTPv1-U p. 21
5.2.1.1 Solution Description p. 21
5.2.1.2 Evaluation p. 21
5.3 Conclusions p. 21
6 Protocols, procedures and services for Control Plane interfaces p. 21
6.1 General p. 21
6.2 Service Based Architecture p. 22
6.2.1 Common Requirements p. 22
6.2.1.1 Definition of Service and Service Based Architecture p. 22
6.2.1.2 Properties of a NF Service p. 22
6.2.1.3 NF Service Framework p. 24
6.2.1.4 Requirements for solution selection p. 24
6.2.1.5 Additional evaluation criteria for solution selection p. 24
6.2.2 Solution and Protocol Selection (Common Aspects) p. 25
6.2.2.1 Solution 1 - Diameter p. 25
6.2.2.1.1 Solution Description p. 25
6.2.2.1.2 Evaluation p. 26
6.2.2.2 Solution 2 - HTTP p. 26
6.2.2.2.1 Solution Description p. 26
6.2.2.2.1.1 General p. 26
6.2.2.2.1.2 HTTP/1.1 p. 26
6.2.2.2.1.3 HTTP/2 p. 27
6.2.2.2.1.4 Transport protocol p. 28
6.2.2.2.1.5 Support of Server-initiated communication from a server to a client p. 28
6.2.2.2.1.6 Extensibility mechanism p. 31
6.2.2.2.1.7 Load/Overload Control p. 33
6.2.2.2.1.8 Message Priority p. 33
6.2.2.2.1.9 HTTP Proxy p. 33
6.2.2.2.1.10 HTTP Heartbeat mechanism between NFs p. 34
6.2.2.2.2 Evaluation p. 35
6.2.2.3 Solution 3 - GTPv2-C p. 35
6.2.2.3.1 Solution Description p. 35
6.2.2.3.2 Evaluation p. 36
6.2.2.4 Comparison of RESTful and RPC protocol design p. 37
6.2.2.4.1 Characteristics of RPCs p. 37
6.2.2.4.2 Characteristics of REST p. 38
6.2.2.4.3 Degree of Compliance of the stage 2 requirements with RPC p. 39
6.2.2.4.4 Degree of Compliance of the stage 2 requirements with REST p. 39
6.2.2.4.5 Evaluation of RPC p. 40
6.2.2.4.6 Evaluation of REST p. 40
6.2.2.4.7 HTTP APIs types p. 41
6.2.2.4.8 Conclusions p. 42
6.2.2.5 Data Serialization Format p. 42
6.2.2.5.0 Introduction p. 42
6.2.2.5.1 Solution 1 - JSON p. 43
6.2.2.5.1.1 Description p. 43
6.2.2.5.1.2 Evaluation p. 43
6.2.2.5.2 Solution 2 - BSON p. 43
6.2.2.5.2.1 Description p. 43
6.2.2.5.2.2 Evaluation p. 43
6.2.2.5.3 Solution 3 - CBOR p. 44
6.2.2.5.3.1 Description p. 44
6.2.2.5.3.2 Evaluation p. 44
6.2.2.5.4 Solution 4 - Multiple payload formats including binary formats p. 44
6.2.2.5.4.1 Description p. 44
6.2.2.5.4.2 Evaluation p. 47
6.2.2.5.5 Conclusion p. 49
6.2.2.6 Transport protocols p. 49
6.2.2.6.1 Solution 1 - TCP p. 49
6.2.2.6.2 Solution 2 - QUIC/UDP p. 49
6.2.2.6.3 Comparison of transport layer protocols p. 50
6.2.2.7 Interface Definition Language p. 50
6.2.2.7.0 Introduction p. 50
6.2.2.7.1 Solution 1 - YANG/RESTCONF p. 51
6.2.2.7.1.1 Description p. 51
6.2.2.7.1.2 Evaluation p. 51
6.2.2.7.2 Solution 2 - OpenAPI Specification (Swagger) p. 52
6.2.2.7.2.1 Description p. 52
6.2.2.7.2.2 Evaluation p. 52
6.2.2.7.3 Solution 3 - Protocol Buffers p. 52
6.2.2.7.3.1 Description p. 52
6.2.2.7.3.2 Evaluation p. 53
6.2.2.7.4 Solution 4 - JSON Content Rules p. 53
6.2.2.7.4.1 Description p. 53
6.2.2.7.4.2 Evaluation p. 53
6.2.2.7.5 Solution 5 - JSON Schema p. 53
6.2.2.7.5.1 Description p. 53
6.2.2.7.5.2 Evaluation p. 53
6.2.2.7.6 Solution 6 - CBOR IDL p. 53
6.2.2.7.6.1 Description p. 53
6.2.2.7.6.2 Evaluation p. 53
6.2.2.7.7 Comparison of IDLs p. 54
6.2.2.7.8 Conclusion p. 55
6.2.2.8 Comparison of candidate solutions p. 55
6.3 Void
6.4 Session Management Function Procedures and Services p. 59
6.4.1 Requirements p. 59
6.4.1.1 General p. 59
6.4.1.2 Key Principles p. 59
6.4.1.2.1 PDU Connectivity Service p. 59
6.4.1.2.2 Roaming scenarios p. 60
6.4.1.2.3 Single PDU session with multiple PDU session anchors p. 60
6.4.1.2.4 Session and Service Continuity p. 61
6.4.1.2.5 QoS model p. 61
6.4.1.2.6 DN Access Identifier (DNAI) p. 62
6.4.1.2.7 Local Area Data Network (LADN) p. 62
6.4.1.3 Session management procedures involving the SMF p. 62
6.4.1.3.1 Stage 2 procedures p. 62
6.4.1.3.2 Interactions between the AMF and SMF p. 63
6.4.1.3.2.1 General p. 63
6.4.1.3.2.2 During a PDU Session Establishment p. 63
6.4.1.3.2.3 During a PDU Session Modification p. 64
6.4.1.3.2.4 During a PDU Session Release p. 64
6.4.1.3.2.5 During a Xn based inter NG RAN handover p. 64
6.4.1.3.2.6 During an Inter NG RAN N2 based handover p. 64
6.4.1.3.2.7 During a UE triggered Service Request in CM-IDLE state p. 65
6.4.1.3.2.8 During a UE triggered Service Request in CM-CONNECTED state p. 65
6.4.1.3.2.9 During a Network triggered Service Request p. 66
6.4.1.3.2.10 During a CN initiated deactivation of UP connection of an existing PDU session p. 66
6.4.1.3.2.11 During an Inter NG-RAN node N2 based handover, cancel p. 66
6.4.1.3.3 Procedures requirements between the V-SMF and H-SMF p. 66
6.4.1.4 Requirements on Services offered by the SMF p. 67
6.4.1.4.1 Nsmf_PDUSession p. 67
6.4.1.4.1.1 General p. 67
6.4.1.4.1.2 Nsmf_PDUSession_CreateSMContext service operation p. 67
6.4.1.4.1.3 Nsmf_PDUSession_UpdateSMContext service operation p. 68
6.4.1.4.1.4 Nsmf_PDUSession_ReleaseSMContext service operation p. 69
6.4.1.4.1.5 Nsmf_PDUSession_Create service operation p. 69
6.4.1.4.1.6 Nsmf_PDUSession_Update service operation p. 70
6.4.1.4.1.7 Nsmf_PDUSession_Release service operation p. 70
6.5 Access and Mobility Management Function Procedures and Services p. 71
6.5.1 Requirements p. 71
6.5.1.1 General p. 71
6.5.1.2 Procedures between two AMFs p. 71
6.5.1.2.0 General p. 71
6.5.1.2.1 During a Registration Procedure p. 71
6.5.1.2.2 During a Inter NG-RAN node N2 based handover p. 72
6.5.1.2.3 During a Inter NG-RAN node N2 based handover, Cancel p. 72
6.5.1.3 Procedures between the AMF and SMF p. 73
6.5.1.3.1 General p. 73
6.5.1.3.2 Transfer of N1/N2 messages from UE and/or AN p. 73
6.5.1.3.3 Transfer of N1/N2 messages to UE and/or AN p. 73
6.5.1.3.4 Notification of Mobility Events p. 73
6.5.1.4 Procedures between the AMF and PCF p. 74
6.6 Authentication Server Function Procedures and Services p. 75
6.6.1 Requirements p. 75
6.6.1.1 General p. 75
6.6.1.2 AUSF Environment p. 75
6.6.1.3 AUSF Functionalities p. 76
6.6.1.4 Information Elements p. 78
6.6.1.5 State model p. 79
6.6.2 Solution and Protocol Selection for Services offered by the AUSF for use over N12 p. 79
6.6.2.1 Solution 1 - N12 Diameter-based Implementation p. 79
6.6.2.1.1 Solution Description p. 79
6.6.2.1.2 Evaluation p. 79
6.6.3 Conclusion p. 80
6.7 Unified Data Management Services and Operations p. 80
6.7.1 Requirements p. 80
6.7.1.1 General p. 80
6.7.1.2 Architecture Overview p. 80
6.7.1.3 Requirements on Services offered by the UDM to the AMF p. 80
6.7.1.3.1 Nudm_UEContextManagement Service p. 81
6.7.1.3.2 Nudm_SubscriberDataManagement Service p. 81
6.7.1.4 Requirements on Services offered by the UDM to the SMF p. 81
6.7.1.4.1 Nudm_UEContextManagement Service p. 81
6.7.1.4.2 Nudm_SubscriberDataManagement Service p. 82
6.7.1.5 Requirements on Services offered by the UDM to the AUSF p. 82
6.7.1.6 Requirements on Services offered by the UDM to the NEF p. 82
6.7.1.7 Requirements on Services offered by the UDM to the SMSF p. 82
6.8 Network Function Service Registration, Discovery and Selection p. 83
6.8.1 Requirements p. 83
6.8.1.1 General p. 83
6.8.1.2 NF service discovery p. 83
6.8.1.3 NF service selection p. 85
6.8.1.4 NF Service Registration and De-registration p. 85
6.8.2 Solution and Protocol Selection p. 86
6.8.2.1 Solution 1 - NRF interface realized by Service Based Interface p. 86
6.8.2.1.1 Solution Description p. 86
6.8.2.1.2 Evaluation p. 89
6.8.2.2 Solution 2 - Service Discovery and Registration using NRF services p. 89
6.8.2.2.1 Solution Description p. 89
6.8.2.2.2 Evaluation p. 89
6.8.2.3 Solution 3 - Classification and Update of NF Instance Parameters p. 90
6.8.2.3.1 Solution Description p. 90
6.8.2.3.2 Classification of NF Instance Parameters in NRF p. 90
6.8.2.3.3 Update NF Instance Parameters in NRF p. 91
6.8.2.3.4 Subscribe and Notify Change of NF Instance Parameters p. 91
6.8.2.3.5 Evaluation p. 91
6.8.2.4 Solution 4 - Report the Status of NF (NF Service) to the NRF by Management System p. 91
6.8.2.4.1 Solution Description p. 91
6.8.2.4.2 Evaluation p. 92
6.8.3 SMF discovery and selection p. 92
6.8.3.1 Requirements p. 92
6.8.4 UPF discovery and selection p. 93
6.8.5 AUSF discovery and selection p. 94
6.8.5.1 Requirements p. 94
6.8.5.2 Candidate Solutions p. 94
6.8.6 UDM discovery and selection p. 94
6.8.6.1 Requirements p. 94
6.8.7 AMF discovery and selection p. 95
6.8.8 SMSF discovery and selection p. 95
6.8.8.1 Requirements p. 95
6.8.9 Conclusions p. 95
6.9 Unstructured Data Storage Function Procedures and Services p. 95
6.9.1 Requirements p. 95
6.9.2 Solution and Protocol Selection p. 97
6.9.2.1 Solution 1 - Reuse of the Ud interface p. 97
6.9.2.1.1 Solution Description p. 97
6.9.2.1.2 Evaluation p. 97
6.9.2.2 Solution 2 - New Diameter application for data management p. 97
6.9.2.2.1 Solution Description p. 97
6.9.2.2.2 Evaluation p. 98
6.9.2.3 Solution 3 - REST compliant HTTP based solution for managing data in UDSF p. 98
6.9.2.3.1 Solution Description p. 98
6.9.2.3.2 Evaluation p. 99
6.9.2.4 Solution 4 - CQL based solution for managing data in UDSF p. 99
6.9.2.4.1 Solution Description p. 99
6.9.2.4.2 Evaluation p. 99
6.10 Structured Data Storage Function Procedures and Services p. 100
6.10.1 Requirements p. 100
6.10.2 Solution and Protocol Selection p. 102
6.10.2.1 Solution 1 - Reuse of the Ud interface p. 102
6.10.2.1.1 Solution Description p. 102
6.10.2.1.2 Evaluation p. 102
6.10.2.2 Solution 2 - New Diameter application for data management p. 102
6.10.2.2.1 Solution Description p. 102
6.10.2.2.2 Evaluation p. 103
6.10.2.3 Solution 3 - REST compliant HTTP based solution for managing data in UDR p. 103
6.10.2.3.1 Solution Description p. 103
6.10.2.3.2 Evaluation p. 103
6.11 Void
6.12 Network Slice Selection Function Service and Procedures p. 104
