ETSI TS 123 334 V13.10.0 (2020-01)

Digital cellular telecommunications system (Phase 2+) (GSM); Universal Mobile Telecommunications System (UMTS); LTE; IP Multimedia Subsystem (IMS) Application Level Gateway (IMS-ALG) - IMS Access Gateway (IMS-AGW) interface: Procedures descriptions (3GPP TS 23.334 version 13.10.0 Release 13)

RTS/TSGC-0423334vda0

General Information

• Status: Published
• Publication Date: 12-Jan-2020
• Technical Committee: 3GPP CT 4 - MAP/CAMEL/GTP/BCH/SS/TrFO/IMS/GUP/WLAN (formely CN4)
• Current Stage: 12 - Completion
• Completion Date: 13-Jan-2020

Standards Content (Sample)

TECHNICAL SPECIFICATION
Digital cellular telecommunications system (Phase 2+) (GSM);
Universal Mobile Telecommunications System (UMTS);
LTE;
IP Multimedia Subsystem (IMS)
Application Level Gateway (IMS-ALG) -
IMS Access Gateway (IMS-AGW) interface:
Procedures descriptions
(3GPP TS 23.334 version 13.10.0 Release 13)

3GPP TS 23.334 version 13.10.0 Release 13 1 ETSI TS 123 334 V13.10.0 (2020-01)

Reference
RTS/TSGC-0423334vda0
Keywords
GSM,LTE,UMTS
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ETSI
3GPP TS 23.334 version 13.10.0 Release 13 2 ETSI TS 123 334 V13.10.0 (2020-01)
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ETSI
3GPP TS 23.334 version 13.10.0 Release 13 3 ETSI TS 123 334 V13.10.0 (2020-01)
Contents
Intellectual Property Rights . 2
Legal Notice . 2
Modal verbs terminology . 2
Foreword . 8
1 Scope . 9
2 References . 9
3 Definitions, symbols and abbreviations . 13
3.1 Definitions . 13
3.2 Symbols . 13
3.3 Abbreviations . 14
4 Architecture . 14
4.1 Reference architecture . 14
4.2 NAT Function . 16
4.3 ATCF/ATGW Function . 17
4.4 eP-CSCF/eIMS-AGW Function . 17
5 Functional Requirements . 18
5.1 General . 18
5.2 Gate Control & Local NAT . 18
5.3 IP realm indication and availability . 18
5.4 Remote NAT traversal support . 19
5.5 Remote Source Address/Port Filtering . 19
5.6 Traffic Policing . 19
5.7 Hanging Termination Detection . 19
5.8 QoS Packet Marking . 20
5.9 Handling of RTCP streams . 20
5.10 Media Inactivity Detection . 21
5.11 IMS Media Plane Security . 21
5.11.1 General . 21
5.11.2 End-to-access-edge Security . 22
5.11.2.1 End-to-access-edge security for RTP based media using SDES . 22
5.11.2.2 End-to-access-edge security for TCP based media using TLS . 23
5.11.2.2.1 General . 23
5.11.2.2.2 e2ae security for session based messaging (MSRP) . 24
5.11.2.2.3 e2ae security for conferencing (BFCP) . 25
5.11.2.3 End-to-access-edge security for UDP based media using DTLS . 25
5.11.2.3.1 General . 25
5.11.2.3.2 e2ae security for T.38 fax over UDP/UDPTL transport . 25
5.11.2.4 End-to-access-edge security for RTP based media using DTLS-SRTP . 26
5.11.2.5 End-to-access-edge security for RTP based voice and video media using DTLS-SRTP over TCP. 27
5.11.2.6 End-to-access-edge security for WebRTC data channels using UDP/DTLS/SCTP transport . 28
5.11.3 End-to-end Security . 28
5.11.3.1 End-to-end security for RTP based media . 28
5.11.3.2 End-to-end security for TCP-based media using TLS . 28
5.12 Explicit Congestion Notification support . 28
5.12.1 General . 28
5.12.2 Incoming SDP offer with ECN . 29
5.12.3 Incoming SDP offer without ECN . 29
5.12.4 Detection of ECN failures by IMS-AGW . 29
5.13 Transcoding . 29
5.13.1 General . 29
5.13.2 Handling of common codec parameters. 30
5.13.3 Handling of the EVS speech codec . 31
5.13.4 Handling of the OPUS speech and audio codec for WebRTC . 48
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5.14 Multimedia Priority Service (MPS) Support . 51
5.15 Coordination of Video Orientation . 52
5.16 Generic image attributes . 53
5.17 TCP bearer connection control . 53
5.17.1 Stateless TCP handling . 53
5.17.2 State-aware TCP handling . 54
5.17.2.1 General . 54
5.17.2.2 State-aware TCP handling without support of modifying the TCP setup direction . 54
5.17.2.3 State-aware TCP handling with support of modifying the TCP setup direction . 55
5.18 Interactive Connectivity Establishment (ICE) . 57
5.18.1 General . 57
5.18.2 ICE lite . 57
5.18.3 Full ICE . 59
5.18.4 STUN consent freshness for WebRTC . 61
5.19 MSRP handling . 61
5.19.1 General . 61
5.19.2 IMS-ALG procedures to support IETF RFC 6714 with application agnostic MSRP handling by the
IMS-AGW . 62
5.19.3 IMS-ALG procedures to support IETF draft-ietf-simple-msrp-sessmatch with application agnostic
MSRP handling by the IMS-AGW . 62
5.19.4 IMS-ALG procedures for application aware MSRP interworking by the IMS-AGW . 63
5.19.5 Application-aware MSRP interworking at the IMS-AGW . 63
5.19.6 MSRP data channels . 63
5.20 Web Real-Time Communication (WebRTC) . 64
5.20.1 General . 64
5.20.2 WebRTC data channel . 65
5.20.2.1 General . 65
5.20.2.2 Data Channel Establishment . 65
5.20.2.3 Data Channel Release . 70
5.20.2.3.1 General . 70
5.20.2.3.2 Release of one WebRTC data channel . 71
5.20.2.3.3 Release of all or last active WebRTC data channels within an SCTP Association . 72
5.20.3 Media Plane Optimization . 72
5.20.3.1 General . 72
5.20.3.2 WIC originating call . 73
5.20.3.3 WIC terminating call . 73
5.21 Alternate Connection (ALTC) Addresses Management . 74
5.21.1 General . 74
5.22 Video Region-of-Interest (ROI) . 74
5.22.1 General . 74
5.22.2 "Far End Camera Control" mode . 75
5.22.3 "Predefined ROI" mode . 75
5.22.4 "Arbitrary ROI" mode. 76
5.23 SDP Capability Negotiation (SDPCapNeg) . 77
6 IMS-ALG to IMS-AGW Procedures . 77
6.1 Non-Call Related Procedures . 77
6.1.1 General . 77
6.1.2 IMS-AGW Unavailable . 78
6.1.3 IMS-AGW Available . 78
6.1.4 IMS-AGW Recovery . 79
6.1.5 IMS-ALG Recovery . 80
6.1.5.1 General . 80
6.1.5.2 IMS-ALG Restoration . 80
6.1.6 IMS-AGW Re-register . 80
6.1.7 IMS-AGW Re-registration Ordered by IMS-ALG . 81
6.1.8 Audit of IMS-AGW . 81
6.1.8.1 Audit of Value . 81
6.1.8.2 Audit of Capability . 82
6.1.9 IMS-AGW Capability Change . 82
6.1.10 IMS-ALG Out of service . 82
6.1.11 IMS-AGW Resource Congestion Handling - Activate . 83
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6.1.12 MGW Resource Congestion Handling -Indication . 83
6.1.13 Control association monitoring . 83
6.1.14 Realm Availability Monitoring . 84
6.1.15 Failure of IP Port, Interface or Group of Interfaces . 85
6.2 Call Related Procedures . 85
6.2.1 Gate Control & Local NA(P)T procedure . 85
6.2.2 IP realm indication procedure . 88
6.2.3 Remote NA(P)T traversal support procedure . 88
6.2.4 Remote Source Address/Port Filtering . 88
6.2.5 Traffic Policing . 89
6.2.6 Hanging Termination Detection . 89
6.2.7 QoS Packet Marking . 90
6.2.8 Media Inactivity Detection . 90
6.2.9 Handling of RTCP streams . 91
6.2.10 IMS end-to-access-edge Media Plane Security. 91
6.2.10.1 General . 91
6.2.10.2 End-to-access-edge security for RTP based media using SDES . 91
6.2.10.3 End-to-access-edge security for TCP-based media using TLS . 91
6.2.10.3.1 End-to-access-edge security for session based messaging (MSRP) . 91
6.2.10.3.1.1 IMS UE originating procedures for e2ae . 91
6.2.10.3.1.1.1 Incoming TCP bearer establishment triggers an outgoing TCP bearer establishment . 91
6.2.10.3.1.1.2 IMS-ALG requests sending an outgoing TCP bearer establishment . 94
6.2.10.3.1.2 IMS UE terminating procedures for e2ae . 96
6.2.10.3.1.2.1 Incoming TCP bearer establishment triggers an outgoing TCP bearer establishment . 96
6.2.10.3.1.2.2 IMS-ALG requests sending an outgoing TCP bearer establishment . 99
6.2.10.3.2 End-to-access-edge security for conferencing (BFCP) . 101
6.2.10.3.2.1 IMS UE originating procedures for e2ae . 101
6.2.10.3.2.1.1 Incoming TCP bearer establishment triggers an outgoing TCP bearer establishment . 101
6.2.10.3.2.2 IMS UE terminating procedures for e2ae . 104
6.2.10.3.2.2.1 Incoming TCP bearer establishment triggers an outgoing TCP bearer establishment . 104
6.2.10.4 End-to-access-edge security for UDP based media using DTLS . 107
6.2.10.4.1 General . 107
6.2.10.4.2 Session establishment from IMS access network for T.38 fax using "UDP/TLS/UDPTL" . 107
6.2.10.4.3 Session establishment towards IMS access network for T.38 fax using "UDP/TLS/UDPTL" . 110
6.2.10.4.4 IMS-AGW procedure for e2ae security of T.38 fax using "UDP/TLS/UDPTL" . 112
6.2.10.4.5 DTLS session establishment failure indication . 112
6.2.10.5 End-to-access-edge security for RTP based media using DTLS-SRTP . 113
6.2.10.6 End-to-access-edge security for WebRTC data channels using SCTP-over-DTLS transport . 117
6.2.10.6.1 General . 117
6.2.10.6.2 Call flow for data channel establishment from WIC towards IMS access network and MSRP
session establishment . 117
6.2.10A IMS end-to-end Media Plane Security . 120
6.2.10A.1 End-to-end security for RTP based media using SDES . 120
6.2.10A.2 End-to-end security for TCP-based media using TLS . 120
6.2.11 Change Through-Connection . 120
6.2.12 Emergency Calls . 120
6.2.13 Explicit Congestion Notification support . 120
6.2.13.1 General . 120
6.2.13.2 ECN Active Indicated (ECN transparent) . 120
6.2.13.3 ECN support requested (ECN endpoint) . 121
6.2.13.4 ECN Failure Indication (ECN endpoint) . 121
6.2.14 Access Transfer procedures with media anchored in IMS-AGW (ATGW) . 122
6.2.14.1 General . 122
6.2.14.2 H.248 context model . 122
6.2.14.3 PS session origination or termination with media anchoring in IMS-AGW (ATGW) signaling
procedures . 124
6.2.14.4 PS to CS Access Transfer procedure with media anchored in IMS-AGW (ATGW) . 126
6.2.14.5 ECN support during PS to CS Access Transfer procedure with media anchored in IMS-AGW
(ATGW) . 127
6.2.14.6 Support of generic image attributes . 128
6.2.14.6.1 General . 128
6.2.14.6.2 Indication of generic image attributes . 129
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6.2.14.7 Handling of common codec parameters . 129
6.2.14.8 EVS speech codec support . 130
6.2.15 Multimedia Priority Congestion Control Procedures . 145
6.2.15.1 General . 145
6.2.15.2 IMS-AGW Resource Congestion in ADD response, request is queued . 145
6.2.15.3 IMS-AGW Resource Congestion in ADD response, IMS-ALG seizes new IMS-AGW . 146
6.2.15.4 IMS-AGW Priority Resource Allocation . 146
6.2.15.5 IMS-AGW Priority User Data marking . 147
6.2.15.6 IMS-AGW Priority Modification . 147
6.2.16 Coordination of Video Orientation . 148
6.2.17 Procedures for Interactive Connectivity Establishment (ICE) . 149
6.2.17.1 ICE lite . 149
6.2.17.2 Full ICE . 149
6.2.17.3 Connectivity check result notification (full ICE) . 150
6.2.17.4 New peer reflexive candidate notification (full ICE) . 150
6.2.17.5 STUN consent freshness test . 151
6.2.17.6 STUN Consent Freshness Test Failure Notification . 152
6.2.18 TCP bearer connection control . 152
6.2.18.1 General . 152
6.2.18.2 Stateless TCP handling . 152
6.2.18.3 State-aware TCP handling without support of modifying the TCP setup direction . 152
6.2.18.4 State-aware TCP handling with support of modifying the TCP setup direction . 152
6.2.19 Application-aware MSRP interworking at the IMS-AGW . 154
6.2.20 Alternate Connection (ALTC) Addresses Management . 155
6.2.21 Video Region-of-Interest (ROI) . 157
6.2.21.1 Video Region-of-Interest (ROI) using FECC. 157
6.2.21.2 "Predefined ROI" mode . 158
6.2.21.3 "Arbitrary ROI" mode . 159
6.2.22 WebRTC . 160
6.2.22.1 Establishment of a WebRTC data channel . 160
6.2.22.2 Release of a WebRTC data channel . 160
6.2.22.3 Media Plane Optimization . 162
7 Charging . 164
8 Messages/Procedures and Contents . 164
8.1 General . 164
8.2 Reserve and Configure AGW Connection Point . 165
8.3 Reserve AGW Connection Point Procedure . 173
8.4 Configure AGW Connection Point Procedure . 180
8.5 Release AGW Termination . 188
8.6 Termination heartbeat indication . 188
8.7 IMS-AGW Out-of-Service . 189
8.8 IMS-AGW Communication Up . 189
8.9 IMS-AGW Restoration . 190
8.10 IMS-AGW Register . 190
8.11 IMS-ALG Restoration . 191
8.12 IMS-AGW Re-register . 191
8.13 IMS-ALG Ordered Re-registration . 192
8.14 Audit Value . 192
8.15 Audit Capability . 193
8.16 Capability Update . 193
8.17 IMS-ALG Out of Service . 194
8.18 IMS-AGW Resource Congestion Handling - Activate. 194
8.19 IMS-AGW Resource Congestion Handling - Indication . 195
8.20 Inactivity Timeout Activate . 195
8.21 Inactivity Timeout Notification . 196
8.22 Command Reject . 196
8.23 Realm Availability Activate . 197
8.24 Realm Availability Notification . 197
8.25 IP Bearer Released . 198
8.26 Media Inactivity Notification . 198
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8.27 Termination Out-of-Service . 199
8.28 Change Through-Connection . 199
8.29 Change Flow Direction . 200
8.30 ECN Failure Indication . 200
8.31 Notify (D)TLS session establishment Failure Indication . 201
8.32 Notify TCP connection establishment Failure Indication . 201
8.33 ICE Connectivity Check Result Notification . 202
8.34 ICE New Peer Reflexive Candidate Notification . 202
8.35 STUN Consent Freshness Test Failure Notification . 203
8.36 Notify SCTP Stream Reset . 203
8.37 Notify SCTP Stream Reset Result . 204
Annex A (informative): Change history . 205
History . 207

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3GPP TS 23.334 version 13.10.0 Release 13 8 ETSI TS 123 334 V13.10.0 (2020-01)
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.
ETSI
3GPP TS 23.334 version 13.10.0 Release 13 9 ETSI TS 123 334 V13.10.0 (2020-01)
1 Scope
Annex G of 3GPP TS 23.228 [2] gives out an IMS Application Level Gateway (IMS-ALG) and IMS Access Media
Gateway (IMS-AGW) based reference model to support NAPT-PT, gate control and traffic policing between IP-CAN
and IMS domain.
Figure 1.1: Scope of the specification
Figure 1.1 illustrates the reference model for Iq:
- the dashed line represents the IP signalling-path with SIP (at Gm) as call/session control protocol between the
UE and the P-CSCF (IMS-ALG);
- the bold, horizontal line represents the IP media-path (also known as (IP) bearer-path or (IP) data-path; the
notion 'media' is used as generic term for "IP application data"); and
- the vertical line represents the Iq control-path with H.248 as gateway/policy control protocol betwe
...