ETSI TS 129 561 V15.3.0 (2019-10)

5G; 5G System; Interworking between 5G Network and external Data Networks; Stage 3 (3GPP TS 29.561 version 15.3.0 Release 15)

RTS/TSGC-0329561vf30

General Information

• Status: Published
• Publication Date: 13-Oct-2019
• Technical Committee: 3GPP CT 3 - Interworking with external networks (formely CN3)
• Current Stage: 12 - Completion
• Completion Date: 14-Oct-2019

Standards Content (Sample)

ETSI TS 129 561 V15.3.0 (2019-10)






TECHNICAL SPECIFICATION
5G;
5G System;
Interworking between 5G Network and external Data Networks;
Stage 3
(3GPP TS 29.561 version 15.3.0 Release 15)

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3GPP TS 29.561 version 15.3.0 Release 15 1 ETSI TS 129 561 V15.3.0 (2019-10)



Reference
RTS/TSGC-0329561vf30
Keywords
5G
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3GPP TS 29.561 version 15.3.0 Release 15 2 ETSI TS 129 561 V15.3.0 (2019-10)
Intellectual Property Rights
Essential patents
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Legal Notice
This Technical Specification (TS) has been produced by ETSI 3rd Generation Partnership Project (3GPP).
The present document may refer to technical specifications or reports using their 3GPP identities. These shall be
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ETSI

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3GPP TS 29.561 version 15.3.0 Release 15 3 ETSI TS 129 561 V15.3.0 (2019-10)
Contents
Intellectual Property Rights . 2
Legal Notice . 2
Modal verbs terminology . 2
Foreword . 5
1 Scope . 6
2 References . 6
3 Definitions and abbreviations . 7
3.1 Definitions . 7
3.2 Abbreviations . 8
4 Network Characteristics . 8
4.1 Key characteristics of PLMN . 8
4.2 Key characteristics of IP Networks . 8
4.3 Key characteristics of Ethernet . 8
5 Interworking Classifications. 8
5.1 Service Interworking . 8
5.2 Network Interworking . 8
6 Reference Architecture . 9
7 Interface to 5G Network services (User Plane) . 9
8 Interworking with DN (IP) . 9
8.1 General . 9
8.2 DN Interworking Model . 9
8.2.1 General . 9
8.2.2 Access to DN through 5G Network . 10
8.2.2.1 Transparent access to DN . 10
8.2.2.2 IPv4 Non-transparent access to DN . 11
8.2.2.3 IPv6 Non-transparent access to DN . 12
9 Interworking with DN (Unstructured) . 13
9.1 General . 13
9.2 N6 PtP tunnelling based on UDP/IP . 13
9.3 Other N6 tunnelling mechanism . 15
10 Interworking with DN (DHCP) . 15
10.1 General . 15
10.2 DN interworking Model of SMF for DHCP . 15
10.2.1 Introduction. 15
10.2.2 IPv4 Address allocation and IPv4 parameter configuration via DHCPv4 . 16
10.2.3 IPv6 Prefix allocation via IPv6 stateless address autoconfiguration via DHCPv6 . 17
10.2.4 IPv6 parameter configuration via stateless DHCPv6 . 19
11 Interworking with DN (RADIUS) . . 19
11.1 RADIUS procedures. 19
11.1.1 RADIUS Authentication and Authorization . 19
11.1.2 RADIUS Accounting . 20
11.2 Message flows on N6 interface . 21
11.2.1 Authentication, Authorization and Accounting procedures . 21
11.2.2 Accounting Update . 23
11.2.3 DN-AAA initiated QoS flow termination . 24
11.2.4 DN-AAA initiated re-authorization . 25
11.3 List of RADIUS attributes . 25
11.3.1 General . 25
11.3.2 Change-of-Authorization Request (optionally sent from DN-AAA server to SMF) . 32
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3GPP TS 29.561 version 15.3.0 Release 15 4 ETSI TS 129 561 V15.3.0 (2019-10)
11.3.3 Access-Challenge (sent from DN-AAA server to SMF) . 33
12 Interworking with DN (Diameter) . 33
12.1 Diameter Procedures . 33
12.1.1 Diameter Authentication and Authorization . 33
12.1.2 Diameter Accounting . 34
12.2 Message flows on N6 interface . 35
12.2.1 Authentication, Authorization and Accounting procedures . 35
12.2.2 Accounting Update . 37
12.2.3 DN-AAA initiated QoS flow termination . 38
12.2.4 DN-AAA initiated re-authorization . 38
12.3 N6 specific AVPs . 39
12.4 N6 re-used AVPs . 39
12.4.0 General . 39
12.4.1 Use of the Supported-Features AVP on the N6 reference point . 42
12.5 N6 specific Experimental-Result-Code AVP . 43
12.6 N6 Diameter messages . 43
12.6.1 General . 43
12.6.2 DER Command . 44
12.6.3 DEA Command . 45
12.6.4 RAR Command . 46
12.6.5 RAA Command . 46
13 Interworking with IMS . 47
13.1 General . 47
13.2 IMS interworking Model . 47
13.2.1 Introduction. 47
13.2.2 IMS specific configuration in the SMF . 47
13.2.3 IMS specific procedures in the SMF . 48
13.2.3.1 Provisioning of Signalling Server Address . 48
13.2.3.2 Failure of Signalling Server Address . 48
14 Interworking with DN (Ethernet) . 48
Annex A (informative): Change history . 50
History . 51

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3GPP TS 29.561 version 15.3.0 Release 15 5 ETSI TS 129 561 V15.3.0 (2019-10)
Foreword
rd
This Technical Specification has been produced by the 3 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.
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3GPP TS 29.561 version 15.3.0 Release 15 6 ETSI TS 129 561 V15.3.0 (2019-10)
1 Scope
The present specification defines the stage 3 interworking procedures for 5G Network interworking between PLMN and
external DN.
The stage 2 requirements and procedures are contained in 3GPP TS 23.501 [2] and 3GPP TS 23.502 [3].
For interworking between 5G PLMN and external DNs, the present document is valid for both 3GPP accesses and non-
3GPP accesses.
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 29.281: "General Packet Radio System (GPRS) Tunnelling Protocol User Plane
(GTPv1-U)".
[5] 3GPP TS 29.061: "Interworking between the Public Land Mobile Network (PLMN) supporting
packet based services and Packet Data Networks (PDN)".
[6] IETF RFC 3748: "Extensible Authentication Protocol (EAP)".
[7] IETF RFC 3579: "RADIUS (Remote Authentication Dial In User Service) Support For Extensible
Authentication Protocol (EAP)".
[8] IETF RFC 2865: "Remote Authentication Dial In User Service (RADIUS)".
[9] IETF RFC 3162: "RADIUS and IPv6".
[10] IETF RFC 4818: "RADIUS Delegated-IPv6-Prefix Attribute".
[11] IETF RFC 5216: "The EAP-TLS Authentication Protocol".
[12] 3GPP TS 23.228: "IP Multimedia Subsystem (IMS); Stage 2".
[13] 3GPP TS 24.229: "IP Multimedia Call Control Protocol based on SIP and SDP; Stage 3".
[14] IETF RFC 2132: "DHCP Options and BOOTP Vendor Extensions".
[15] IETF RFC 3361: "Dynamic Host Configuration Protocol (DHCP-for-IPv4) Option for Session
Initiation Protocol (SIP) Servers".
[16] IETF RFC 3646: "DNS Configuration options for Dynamic Host Configuration Protocol for IPv6
(DHCPv6)".
[17] IETF RFC 3319: "Dynamic Host Configuration Protocol (DHCPv6) Options for Session Initiation
Protocol (SIP) Servers".
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3GPP TS 29.561 version 15.3.0 Release 15 7 ETSI TS 129 561 V15.3.0 (2019-10)
[18] IETF RFC 2131: "Dynamic Host Configuration Protocol".
[19] IETF RFC 1542: "Clarification and Extensions for the Bootstrap Protocol".
[20] IETF RFC 4039: "Rapid Commit Option for the Dynamic Host Configuration Protocol version 4
(DHCPv4)".
[21] IETF RFC 3315: "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)".
[22] IETF RFC 3736: "Stateless Dynamic Host Configuration Protocol (DHCP) Service for IPv6".
[23] IETF RFC 7155: "Diameter Network Access Server Application".
[24] IETF RFC 6733: "Diameter Base Protocol".
[25] IETF RFC 4072: "Diameter Extensible Authentication Protocol (EAP) Application".
[26] IETF RFC 2866: "RADIUS Accounting".
[27] IETF RFC 5176: "Dynamic Authorization Extentions to Remote Authentication Dial In User
Service (RADIUS)".
[28] 3GPP TS 23.003: "Numbering, addressing and identification".
[29] IETF RFC 1825: "Security Architecture for the Internet Protocol".
[30] IETF RFC 1826: "IP Authentication Header".
[31] IETF RFC 1827: "IP Encapsulating Security Payload (ESP)".
[32] IETF RFC 4291: "IP Version 6 Addressing Architecture".
[33] IETF RFC 4861: "Neighbor Discovery for IP Version 6 (IPv6)".
[34] IETF RFC 4862: "IPv6 Stateless Address Autoconfiguration".
[35] IETF RFC 1027: "Using ARP to Implement Transparent Subnet Gateways".
[36] 802.3-2015 - IEEE Standard for Ethernet.
[37] IETF RFC 5281: "Extensible Authentication Protocol Tunneled Transport Layer Security
Authenticated Protocol Version 0 (EAP-TTLSv0)".
[38] 3GPP TS 23.380: "IMS Restoration Procedures".
[39] 3GPP TS 29.571: "5G System; Common Data Types for Service Based Interfaces; Stage 3".
[40] 3GPP TS 29.502: "5G System; Session Management Services; Stage 3".
[41] 3GPP TS 29.229: "Cx and Dx interfaces based on Diameter protocol; Protocol details".
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the terms and definitions given in 3GPP TR 21.905 [1] and the following
apply. A term defined in the present document takes precedence over the definition of the same term, if any, in
3GPP TR 21.905 [1].
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3GPP TS 29.561 version 15.3.0 Release 15 8 ETSI TS 129 561 V15.3.0 (2019-10)
3.2 Abbreviations
For the purposes of the present document, the abbreviations given in 3GPP TR 21.905 [1] and the following apply. An
abbreviation defined in the present document takes precedence over the definition of the same abbreviation, if any, in
3GPP TR 21.905 [1].
CSMA/CD Carrier Sense Multiple Access/Collision Detection
DHCPv4 Dynamic Host Configuration Protocol version 4
DHCPv6 Dynamic Host Configuration Protocol version 6
DN Data Network
GPSI Generic Public Subscription Identifier
N3IWF Non-3GPP InterWorking Function
PtP Point-to-Point
SFD Start Frame Delimiter
SMF Session Management Function
SSC Session and Service Continuity
UPF User Plane Function
WAN Wide Area Network
4 Network Characteristics
4.1 Key characteristics of PLMN
The PLMN is fully defined in the 3GPP technical specifications. The 5G Network related key characteristics are
defined in 3GPP TS 23.501 [2].
4.2 Key characteristics of IP Networks
The Internet is a conglomeration of networks utilising a common set of protocols. IP protocols are defined in the
relevant IETF RFCs. The networks topologies may be based on LANs (e.g. Ethernet), Point to Point leased lines,
PSTN, ISDN, X.25 or WANs using switched technology (e.g. SMDS, ATM).
4.3 Key characteristics of Ethernet
The Ethernet is a family of computer networking technologies commonly used in LAN and is often used to refer to all
Carrier Sense Multiple Access/Collision Detection (CSMA/CD) LANs that generally conform to Ethernet
Specifications, including IEEE 802.3 [36]. The key characteristics for Ethernet are defined in IEEE 802.3 [36].
5 Interworking Classifications
5.1 Service Interworking
Service interworking is required when the Teleservice at the calling and called terminals are different. No service
interworking is specified in this specification.
5.2 Network Interworking
Network interworking is required whenever a PLMN is involved in communications with another network to provide
end-to-end communications. The PLMN shall interconnect in a manner consistent with that of a normal Data Network
(type defined by the requirements e.g. IP). Interworking appears exactly like that of Data Networks.
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3GPP TS 29.561 version 15.3.0 Release 15 9 ETSI TS 129 561 V15.3.0 (2019-10)
6 Reference Architecture
Figure 6-1 shows the access interfaces for the 5G Network. The 5G Network includes both the 3GPP access and the
non-3GPP access.
SMF
NG-RAN UPF Data Networks
UE
5G network
N6

Figure 6-1: Reference Architecture for 5G Network Interworking
7 Interface to 5G Network services (User Plane)
The user plane for 5G Network services is defined in subclause 8.3 of 3GPP TS 23.501 [2] and 3GPP TS 29.281 [4].
8 Interworking with DN (IP)
8.1 General
5GS shall support interworking with DNs based on the Internet Protocol (IP). These interworked networks may be
either intranets or the Internet.
8.2 DN Interworking Model
8.2.1 General
When interworking with the IP networks, the 5GS can operate IPv4 and/or IPv6. The interworking point is shown in
clause 6.
The UPF for interworking with the IP network is the 5GS access point (see figure 8.2.1-1).
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3GPP TS 29.561 version 15.3.0 Release 15 10 ETSI TS 129 561 V15.3.0 (2019-10)

UPF
N6

IP IP


L2
 5G protocol layers

L1

Figure 8.2.1-1: The protocol stacks of UPF for the IP network interworking
Typically, in the IP networks, the interworking with subnetworks is done via IP routers. The N6 reference point is
between the UPF and the external IP network. From the external IP network's point of view, the UPF is seen as a
normal IP router. The L2 and L1 layers are operator specific.
It is out of the scope of the present document to standardise the router functions and the used protocols in the N6
reference point.
Interworking with user defined ISPs and private/public IP networks is subject to interconnect agreements between the
network operators.
8.2.2 Access to DN through 5G Network
8.2.2.1 Transparent access to DN

N6
5GS UPF
Operator
specific
External IP
DHCP
IP Firewall /
Network
Network Proxy
DNS

Figure 8.2.2.1-1: Example of the DN Interworking Model, transparent case
In figure 8.2.2.1-1, an example DN interworking model for transparent access to the Internet is provided for an UPF in
the 5GS and its N6 reference point.
In transparent access to the Internet case:
- the UE is given an IPv4 address and/or an IPv6 prefix belonging to the operator addressing space. The IPv4
address and/or IPv6 prefix is assigned either at subscription in which case it is a static address or at PDU session
establishment in which case it is a dynamic address. This IPv4 address and/or IPv6 prefix if applicable is used
for packet forwarding between the Internet and the UPF and within the 5GS. With IPv6, Stateless Address
Autoconfiguration shall be used to assign an IPv6 address to the UE. These procedures are as described in the
IPv6 non-transparent access case except that the addresses belong to the operator addressing space.
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3GPP TS 29.561 version 15.3.0 Release 15 11 ETSI TS 129 561 V15.3.0 (2019-10)
- the UE need not send any authentication request at PDU session establishment procedure and the SMF/UPF need
not take any part in the user authentication/authorization process.
The transparent case provides at least a basic ISP service. As a consequence of this it may therefore provide a QoS flow
service for a tunnel to a private Intranet. The user level configuration may be carried out between the UE and the
intranet, the 5GS is transparent to this procedure. The used protocol stack is depicted in figure 8.2.2.1-2.
In tran et In tra n e t

p rotoc o l pro toc ol
 IP  IP  IP  IP
 L2/L1  L2/L1
5G proto c ol lay ers
UE UPF Intranet

Figure 8.2.2.1-2: Transparent access to an Intranet
The communication between the PLMN and the Intranet may be performed over any network, even an insecure network
e.g. the Internet. There is no specific security protocol between the UPF and the Intranet because security is ensured on
an end to end basis between the UE and the intranet by the "Intranet Protocol".
User aut
...