ETSI TS 124 502 V17.10.0 (2024-07)

5G; Access to the 3GPP 5G Core Network (5GCN) via non-3GPP access networks (3GPP TS 24.502 version 17.10.0 Release 17)

RTS/TSGC-0124502vha0

General Information

• Status: Not Published
• Technical Committee: 3GPP CT 1 - MM/CC/SM [lu] (formely CN1)
• Current Stage: 12 - Citation in the OJ (auto-insert)
• Completion Date: 29-Jul-2024

Standards Content (Sample)

TECHNICAL SPECIFICATION
5G;
Access to the 3GPP 5G Core Network (5GCN)
via non-3GPP access networks
(3GPP TS 24.502 version 17.10.0 Release 17)

3GPP TS 24.502 version 17.10.0 Release 17 1 ETSI TS 124 502 V17.10.0 (2024-07)

Reference
RTS/TSGC-0124502vha0
Keywords
5G
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ETSI
3GPP TS 24.502 version 17.10.0 Release 17 2 ETSI TS 124 502 V17.10.0 (2024-07)
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ETSI
3GPP TS 24.502 version 17.10.0 Release 17 3 ETSI TS 124 502 V17.10.0 (2024-07)
Contents
Intellectual Property Rights . 2
Legal Notice . 2
Modal verbs terminology . 2
Foreword . 7
1 Scope . 8
2 References . 8
3 Definitions, symbols and abbreviations . 10
3.1 Definitions . 10
3.2 Abbreviations . 11
4 General . 12
4.1 Overview . 12
4.2 Untrusted access . 12
4.3 Identities . 12
4.3.1 User identities . 12
4.3.2 FQDN for N3IWF Selection . 12
4.4 Quality of service support . 13
4.4.1 General . 13
4.4.2 QoS differentiation in non-3GPP access . 13
4.4.2.1 General . 13
4.4.2.2 QoS signalling . 13
4.4.2.3 QoS differentiation in user plane . 14
4.4.2.4 Reflective QoS . 14
4.4.2.5 QoS enforcement . 14
4.5 Trusted access . 14
4.6 Forbidden PLMNs for non-3GPP access to 5GCN . 15
5 Network discovery and selection . 15
5.1 General . 15
5.2 Access network discovery procedure . 16
5.2.1 General . 16
5.2.2 Discovering availability of WLAN access networks . 16
5.3 Access network selection procedure. 16
5.3.1 General . 16
5.3.2 WLAN selection procedure . 16
5.3.2.1 General . 16
5.3.2.2 Manual mode WLAN selection. 17
5.3.2.3 Automatic mode WLAN selection . 17
5.3A PLMN selection procedures using trusted non-3GPP access . 18
5.3A.1 General . 18
5.3A.2 PLMN solicitation . 18
5.3A.3 Manual PLMN selection mode procedure . 19
5.3A.4 Automatic mode PLMN selection procedure . 19
5.3A.4.1 General . 19
5.3A.4.2 Attempting to select HPLMN or equivalent HPLMN . 20
5.3A.4.3 Void. 21
5.3B PLMN selection procedures using wireline access . 21
5.3C PLMN selection procedures for NSWO in 5GS . 21
5.4 Access network reselection procedure . 21
5.4.1 General . 21
5.4.2 WLAN reselection procedure . 21
6 UE - 5GC network protocols . 22
6.1 General . 22
6.2 Void . 22
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6.3 Authentication and authorization for accessing 5GS via non-3GPP access network . 22
6.3.1 General . 22
6.3.2 Authentication of N5GC device behind a CRG over wireline access . 22
6.3a Authentication for NSWO in 5GS . 23
6.4 Handling of ANDSP Information . 23
6.4.1 General . 23
6.4.2 UE procedures . 24
6.4.2.1 General . 24
6.4.2.2 Use of WLAN selection information . 24
6.4.2.3 Use of N3AN node configuration information . 24
6.4.3 ANDSP information from the network . 24
7 Security association management procedures . 24
7.1 General . 24
7.2 N3AN node selection procedure . 25
7.2.1 General . 25
7.2.2 N3AN node configuration information . 25
7.2.3 Determination of the country the UE is located in . 25
7.2.4 N3AN node selection for non-emergency services . 25
7.2.4.1 General . 25
7.2.4.2 Determine if the visited country mandates the selection of N3IWF in this country. 26
7.2.4.3 UE procedure when the UE only supports connectivity with N3IWF . 26
7.2.4.4 UE procedure when the UE supports connectivity with N3IWF and ePDG . 29
7.2.4.4.1 General . 29
7.2.4.4.2 N3AN node selection for IMS service . 29
7.2.4.4.3 N3AN node selection for Non-IMS service . 32
7.2.5 Selection of an N3AN node in an SNPN . 35
7.2.6 N3AN node selection for emergency services . 36
7.2.6.1 General . 36
7.2.6.2 UE procedure when the UE only supports connectivity with N3IWF . 36
7.2.6.3 UE procedure when the UE supports connectivity with N3IWF and ePDG . 36
7.3 IKE SA establishment procedure for untrusted non-3GPP access . 37
7.3.1 General . 37
7.3.2 IKE SA and signalling IPsec SA establishment procedure . 37
7.3.2.1 IKE SA and signalling IPsec SA establishment initiation . 37
7.3.2.2 IKE SA and signalling IPsec SA establishment accepted by the network . 38
7.3.2.3 IKE SA and signalling IPsec SA establishment not accepted by the network . 39
7.3.3 EAP-5G session over non-3GPP access . 41
7.3.3.1 General . 41
7.3.3.1A EAP-5G session initiation . 41
7.3.3.2 EAP-5G session completion initiated by the network . 41
7.3.3.3 EAP-5G session completion initiated by the UE . 42
7.3.4 Abnormal cases in the UE . 43
7.3.5 Abnormal cases in the N3IWF . 43
7.3A IKE SA establishment procedure for trusted non-3GPP access . 43
7.3A.1 General . 43
7.3A.2 EAP session over non-3GPP access . 45
7.3A.2.1 General . 45
7.3A.2.2 Identity transaction . 45
7.3A.2.3 EAP-5G session initiation . 45
7.3A.2.4 EAP-5G session completion initiated by the network . 46
7.3A.2.5 EAP-5G session completion initiated by the UE . 46
7.3A.3 IKE SA and signalling IPsec SA establishment procedure . 46
7.3A.3.1 IKE SA and signalling IPsec SA establishment initiation . 46
7.3A.3.2 IKE SA and signalling IPsec SA establishment accepted by the network . 46
7.3A.3.3 IKE SA and signalling IPsec SA establishment not accepted by the network . 46
7.3A.4 Procedure for devices without NAS support . 47
7.3A.4.1 General . 47
7.3A.4.2 N5CW device registration over trusted WLAN access network . 47
7.4 IKEv2 SA deletion procedure . 48
7.4.1 General . 48
7.4.2 IKE SA deletion procedure initiated by the N3IWF and the TNGF . 48
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7.4.2.1 IKE SA deletion initiation . 48
7.4.2.2 IKE SA deletion accepted by the UE . 48
7.4.2.3 Abnormal cases in the N3IWF and the TNGF . 49
7.4.3 IKE SA deletion procedure initiated by the UE . 49
7.4.3.1 IKE SA deletion initiation . 49
7.4.3.2 IKE SA deletion accepted by the N3IWF and the TNGF . 49
7.4.3.3 Abnormal cases in the UE . 49
7.5 User plane IPsec SA creation procedure . 50
7.5.1 General . 50
7.5.2 Child SA creation procedure initiation . 50
7.5.3 Child SA creation procedure accepted by the UE . 50
7.5.4 Child SA creation procedure not accepted by the UE . 51
7.5.5 Abnormal cases in the UE . 51
7.5.6 Abnormal cases in the N3IWF and the TNGF . 51
7.6 IPsec SA modification procedure . 51
7.6.1 General . 51
7.6.2 N3IWF and TNGF procedure for IPsec child SA modification . 51
7.6.3 UE procedure for IPsec child SA modification. 51
7.7 IPSec SA deletion procedure . 52
7.7.1 General . 52
7.7.2 N3IWF-initated and TNGF-initiated child SA deletion procedure . 52
7.7.2.1 N3IWF-initiated and TNGF-initiated child SA deletion procedure initiation . 52
7.7.2.2 N3IWF-initiated and TNGF-initiated child SA deletion procedure accepted by the UE . 53
7.7.2.3 Abnormal cases in the N3IWF and the TNGF . 53
7.7.3 UE-initiated child SA deletion procedure . 53
7.7.3.1 UE-initiated child SA deletion procedure initiation . 53
7.7.3.2 UE-initiated child SA deletion procedure accepted by the N3IWF and the TNGF. 53
7.7.3.3 Abnormal cases in the UE . 53
7.7.4 Abnormal cases in the UE . 53
7.7.5 Abnormal cases in the N3IWF and the TNGF . 53
7.8 UE-initiated liveness check procedure . 54
7.8.1 General . 54
7.8.2 UE-initiated liveness check procedure initiation . 54
7.8.3 UE-initiated liveness check procedure completion . 54
7.8.4 Abnormal cases . 54
7.9 Network-initiated liveness check procedure . 54
7.9.1 General . 54
7.9.2 Network-initiated liveness check procedure initiation . 54
7.9.3 Network-initiated liveness check procedure completion . 55
7.9.4 Abnormal cases . 55
7.10 IKE SA rekeying procedure . 55
7.10.1 General . 55
7.10.2 N3IWF-initiated and TNGF-initiated IKE SA rekeying procedure . 55
7.10.2.1 N3IWF-initiated and TNGF-initiated IKE SA rekeying procedure initiation . 55
7.10.2.2 N3IWF-initiated and TNGF-initiated IKE SA rekeying procedure completion . 55
7.10.2.3 Abnormal cases . 55
7.10.3 UE-initiated IKE SA rekeying procedure . 56
7.10.3.1 UE-initiated IKE SA rekeying procedure initiation . 56
7.10.3.2 UE-initiated IKE SA rekeying procedure completion . 56
7.10.3.3 Abnormal cases . 56
7.11 IPsec SA rekeying procedure . 56
7.11.1 General . 56
7.11.2 N3IWF-initiated and TNGF-initiated IPsec SA rekeying procedure . 56
7.11.2.1 N3IWF-initiated and TNGF-initiated IPsec SA rekeying procedure initiation . 56
7.11.2.2 N3IWF-initiated and TNGF-initiated IPsec SA rekeying procedure completion . 57
7.11.2.3 Abnormal cases . 57
7.11.3 UE-initiated IPsec SA rekeying procedure . 57
7.11.3.1 UE-initiated IPsec SA rekeying procedure initiation . 57
7.11.3.2 UE-initiated IPsec SA rekeying procedure completion . 57
7.11.3.3 Abnormal cases . 57
7A void . 58
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8 Message transport procedures . 58
8.1 General . 58
8.2 Transport of NAS messages over control plane . 58
8.2.1 General . 58
8.2.2 TCP packet encapsulation . 58
8.2.3 Establishment of TCP connection for transport of NAS messages . 60
8.2.3A Re-establishment of TCP connection for transport of NAS messages . 61
8.2.4 Transport of NAS messages over TCP connection . 61
8.2.5 Release of TCP connection for transport of NAS messages . 61
8.3 Transport of messages over user plane . 61
8.3.1 General . 61
8.3.2 Generic routing encapsulation (GRE) . 62
9 Parameters and coding. 63
9.1 General . 63
9.2 3GPP specific coding information . 63
9.2.1 GUAMI . 63
9.2.2 Establishment cause for non-3GPP access . 64
9.2.3 PLMN ID . 65
9.2.4 IKEv2 Notify Message Type value . 65
9.2.4.1 General . 65
9.2.4.2 Private Notify Message - Error Types . 66
9.2.4.3 Private Notify Message - Status Types . 66
9.2.5 TNGF IPv4 contact info . 67
9.2.6 TNGF IPv6 contact info . 68
9.2.7 NID . 68
9.3 IETF RFC coding information . 69
9.3.1 IKEv2 Notify payloads . 69
9.3.1.1 5G_QOS_INFO Notify payload. 69
9.3.1.2 NAS_IP4_ADDRESS Notify payload . 75
9.3.1.3 NAS_IP6_ADDRESS Notify payload . 75
9.3.1.4 UP_IP4_ADDRESS Notify payload . 76
9.3.1.5 UP_IP6_ADDRESS Notify payload . 77
9.3.1.6 NAS_TCP_PORT Notify payload . 77
9.3.1.7 N3GPP_BACKOFF_TIMER Notify payload . 78
9.3.2 EAP-5G method . 78
9.3.2.1 General . 78
9.3.2.2 Message format . 78
9.3.2.2.1 EAP-Request/5G-Start message . 78
9.3.2.2.2 EAP-Response/5G-NAS message . 79
9.3.2.2.3 EAP-Request/5G-NAS message . 83
9.3.2.2.4 EAP-Response/5G-Stop message . 84
9.3.2.2.5 EAP-Request/5G-Notification message . 85
9.3.2.2.6 EAP-Response/5G-Notification message . 87
9.3.3 GRE encapsulated user data packet . 88
9.4 NAS message envelope . 89
Annex A (informative): Change history . 91
History . 96

ETSI
3GPP TS 24.502 version 17.10.0 Release 17 7 ETSI TS 124 502 V17.10.0 (2024-07)
Foreword
This Technical Specification has been produced by the 3rd Generation Partnership Project (3GPP).
The contents of the present document are subject to continuing work within the TSG and may change following formal
TSG approval. Should the TSG modify the contents of the present document, it will be re-released by the TSG with an
identifying change of release date and an increase in version number as follows:
Version x.y.z
where:
x the first digit:
1 presented to TSG for information;
2 presented to TSG for approval;
3 or greater indicates TSG approved document under change control.
y the second digit is incremented for all changes of substance, i.e. technical enhancements, corrections,
updates, etc.
z the third digit is incremented when editorial only changes have been incorporated in the document.
ETSI
3GPP TS 24.502 version 17.10.0 Release 17 8 ETSI TS 124 502 V17.10.0 (2024-07)
1 Scope
The present document specifies non-3GPP access network discovery and selection procedures, the access authorization
procedure used for accessing non-3GPP access networks. These non-3GPP access networks can be trusted non-3GPP
access networks, untrusted non-3GPP access networks or wireline access networks.
The present document also specifies the security association management procedures used for establishing IKEv2 and
IPsec security associations:
- between the UE and the N3IWF and the procedures for transporting messages between the UE and the N3IWF
over the non-3GPP access networks; and
- between the UE and the TNGF and the procedures for transporting messages between the UE and the TNGF
over the non-3GPP access networks.
The present document also specifies the EAP-5G procedures used for exchange of NAS messages via trusted non-3GPP
access before the UE is authenticated and authorized to use the trusted non-3GPP access.
The present document is applicable to the UE, the 5G-RG, the W-AGF acting on behalf of the FN-RG or the W-AGF
acting on behalf of the N5GC device and the network. In this technical specification the network refers to the 3GPP
5GCN and the trusted non-3GPP access, untrusted non-3GPP access, or wireline access network.
NOTE: The present document is not applicable to the FN-RG.
2 References
The following documents contain provisions which, through reference in this text, constitute provisions of the present
document.
- References are either specific (identified by date of publication, edition number, version number, etc.) or
non-specific.
- For a specific reference, subsequent revisions do not apply.
- For a non-specific reference, the latest version applies. In the case of a reference to a 3GPP document (including
a GSM document), a non-specific reference implicitly refers to the latest version of that document in the same
Release as the present document.
[1] 3GPP TR 21.905: "Vocabulary for 3GPP Specifications".
[2] 3GPP TS 23.501: "System Architecture for the 5G System; Stage 2".
[3] 3GPP TS 23.502: "Procedures for the 5G System; Stage 2".
[4] 3GPP TS 24.501: "Access-Stratum (NAS) protocol for 5G System (5GS); Stage 3".
[4A] 3GPP TS 24.301: "Non-Access-Stratum (NAS) protocol for Evolved Packet System (EPS);
Stage 3".
[5] 3GPP TS 33.501: "Security architecture and procedures for 5G System".
[6] IETF RFC 7296: "Internet Key Exchange Protocol Version 2 (IKEv2)".
[7] 3GPP TS 24.302: "Access to the 3GPP Evolved Packet Core (EPC) via non-3GPP access
networks; Stage 3".
[8] 3GPP TS 23.003: "Numbering, addressing and identification".
[9] IETF RFC 3748: "Extensible Authentication Protocol (EAP)".
[10] 3GPP TS 33.402: "3GPP System Architecture Evolution (SAE); Security aspects of non-3GPP
accesses."
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3GPP TS 24.502 version 17.10.0 Release 17 9 ETSI TS 124 502 V17.10.0 (2024-07)
[11] IETF RFC 4303: "IP Encapsulating Security Payload (ESP)".
[12] IETF RFC 4301: "Security Architecture for the Internet Protocol".
[13] 3GPP TS 23.122: "Non-Access-Stratum (NAS) functions related to Mobile Station (MS) in idle
mode".
[14] IETF RFC 2784: "Generic Routing Encapsulation (GRE)".
[15] IETF RFC 2890: "Key and Sequence Number Extensions to GRE".
[16] 3GPP TS 23.503: "Policy and Charging Control Framework for the 5G System".
[17] 3GPP TS 24.526:
...