ETSI TS 123 527 V15.0.0 (2018-10)

5G; 5G System; Restoration Procedures (3GPP TS 23.527 version 15.0.0 Release 15)

ETSI TS 123 527 V15.0.0 (2018-10)

Name:ETSI TS 123 527 V15.0.0 (2018-10)   Standard name:5G; 5G System; Restoration Procedures (3GPP TS 23.527 version 15.0.0 Release 15)
Standard number:ETSI TS 123 527 V15.0.0 (2018-10)   language:English language
Release Date:03-Oct-2018   technical committee:3GPP CT 4 - MAP/CAMEL/GTP/BCH/SS/TrFO/IMS/GUP/WLAN (formely CN4)
Drafting committee:   ICS number:
ETSI TS 123 527 V15.0.0 (2018-10)






TECHNICAL SPECIFICATION
5G;
5G System;
Restoration Procedures
(3GPP TS 23.527 version 15.0.0 Release 15)

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3GPP TS 23.527 version 15.0.0 Release 15 1 ETSI TS 123 527 V15.0.0 (2018-10)



Reference
DTS/TSGC-0423527vf00
Keywords
5G
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3GPP TS 23.527 version 15.0.0 Release 15 2 ETSI TS 123 527 V15.0.0 (2018-10)
Intellectual Property Rights
Essential patents
IPRs essential or potentially essential to normative deliverables may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (https://ipr.etsi.org/).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
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ETSI claims no ownership of these except for any which are indicated as being the property of ETSI, and conveys no
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not constitute an endorsement by ETSI of products, services or organizations associated with those trademarks.
Foreword
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, UMTS identities or
GSM identities. These should be interpreted as being references to the corresponding ETSI deliverables.
The cross reference between GSM, UMTS, 3GPP and ETSI identities can be found under
.
Modal verbs terminology
In the present document "shall", "shall not", "should", "should not", "may", "need not", "will", "will not", "can" and
"cannot" are to be interpreted as described in clause 3.2 of the ETSI Drafting Rules (Verbal forms for the expression of
provisions).
"must" and "must not" are NOT allowed in ETSI deliverables except when used in direct citation.
ETSI

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3GPP TS 23.527 version 15.0.0 Release 15 3 ETSI TS 123 527 V15.0.0 (2018-10)
Contents
Intellectual Property Rights . 2
Foreword . 2
Modal verbs terminology . 2
Foreword . 4
1 Scope . 5
2 References . 5
3 Definitions and abbreviations . 5
3.1 Definitions . 5
3.2 Abbreviations . 5
4 Restoration Procedures related to the N4 Interface . 5
4.1 General . 5
4.2 N4 Failure and Restart Detection . 6
4.3 UPF Restoration Procedures. 6
4.3.1 General . 6
4.3.2 Restoration Procedure for PSA UPF Restart . 6
4.3.3 Restoration Procedure for PSA UPF Failure without Restart . 6
4.3.4 Restoration Procedure for Intermediate UPF Restart . 6
4.3.5 Restoration Procedure for Intermediate UPF Failure without Restart . 7
4.4 SMF Restoration Procedures . 7
4.4.1 General . 7
4.4.2 Restoration Procedure for SMF Restart . 7
4.4.3 Restoration Procedure for SMF Failure without Restart . 7
4.5 N4 path failure . 7
5 Restoration Procedures related to the User Plane Interfaces N3 and N9 . 7
5.1 General . 7
5.2 User Plane Failure Detection . 8
5.2.1 Loss of GTP-U contexts . 8
5.2.2 User Plane Path Failure . 8
5.3 Restoration Procedures upon Loss of GTP-U contexts . 8
5.3.1 General . 8
5.3.2 Procedure for GTP-U Error Indication received from 5G-AN . 8
5.3.2.1 Principles . 8
5.3.3 Procedure for GTP-U Error Indication received from UPF . 9
5.3.3.1 GTP-U Error Indication received by 5G-AN . 9
5.3.3.2 GTP-U Error Indication received by another UPF . 9
5.4 Restoration Procedures upon User Plane Path Failure . 10
6 Restoration Procedures related to Service-Based Interfaces . 10
6.1 General . 10
6.2 NF (NF Service) Failure and Restart Detection using the NRF . 10
6.2.1 General . 10
6.2.2 NF (NF Service) Failure . 10
6.2.3 NF (NF Service) Restart . 12
Annex A (informative): Change history . 15
History . 16

ETSI

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3GPP TS 23.527 version 15.0.0 Release 15 4 ETSI TS 123 527 V15.0.0 (2018-10)
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

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3GPP TS 23.527 version 15.0.0 Release 15 5 ETSI TS 123 527 V15.0.0 (2018-10)
1 Scope
The present document defines the restoration procedures in the 5G System.
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 23.007: "Restoration procedures".
[3] 3GPP TS 29.281: "General Packet Radio System (GPRS) Tunneling Protocol User Plane (GTPv1-
U)".
[4] 3GPP TS 29.244: "Interface between the Control Plane and the User Plane Nodes; Stage 3".
[5] 3GPP TS 23.502:"Procedures for the 5G System; Stage 2"
[6] 3GPP TS 29.518: "5G System; Access and Mobility Management Service; Stage 3".
[7] 3GPP TS 29.510: "5G System; Network Function Repository Services; Stage 3".

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].
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].
F-SEID Fully Qualified SEID
PFCP Packet Forwarding Control Protocol
PSA PDU Session Anchor

4 Restoration Procedures related to the N4 Interface
4.1 General
This clause specifies the procedures supported in the 5G System to detect and handle failures affecting the N4 interface.
ETSI

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3GPP TS 23.527 version 15.0.0 Release 15 6 ETSI TS 123 527 V15.0.0 (2018-10)
4.2 N4 Failure and Restart Detection
Across PFCP based interfaces an SMF and UPF shall utilize the PFCP Heartbeat Request and Heartbeat Response
messages or PFCP messages containing the Recovery Time Stamp to detect a peer PFCP failure or restart as described
in clause 19A of 3GPP TS 23.007 [2].
4.3 UPF Restoration Procedures
4.3.1 General
When a UPF fails, all its Session contexts and PFCP associations affected by the failure become invalid and may be
deleted.
4.3.2 Restoration Procedure for PSA UPF Restart
If F-TEID allocation is performed in the UPF, the UPF shall ensure that previously used F-TEID values are not
immediately reused after a UPF restart, in order to avoid inconsistent TEID allocation throughout the network and to
enable the restoration of PFCP sessions affected by the failure. How this is ensured is implementation specific.
The UPF shall not send an Error indication message for a configurable period after an UPF restart when the UPF
receives a G-PDU not matching any PDRs.
During or immediately after an UPF Restart, the UPF shall place a local UPF Recovery Time Stamp value in all
Heartbeat Request/Response and PFCP Association Setup Request/Response Messages.
Immediately after the re-establishment of a PFCP association between the SMF and the UPF, the SMF may start
restoring PFCP sessions in the UPF.
4.3.3 Restoration Procedure for PSA UPF Failure without Restart
Procedures for PSA UPF failure without restart are implementation specific.
4.3.4 Restoration Procedure for Intermediate UPF Restart
The SMF will receive the UPF recovery time stamps in the PFCP association setup Request/Response and the PFCP
heartbeat requests/responses.
After an Intermediate UPF restart, the PFCP association between the SMF(s) and the Intermediate UPF has to be re-
established.
The restoration of the PFCP sessions may start immediately after the PFCP association setup procedure:
- if the restoration is supported in the SMF on a proactive basis, the SMF may start re-establishing PFCP sessions
matching any PDRs.
- if the restoration is supported in the SMF on a reactive basis:
- the SMF shall establish an PFCP session with a wildcarded PDR to instruct the Intermediate UPF to forward
G-PDU packets which are not matching any other PDRs to the SMF (to a F-TEID uniquely assigned in the
SMF for this PFCP-u tunnel);
- upon receipt of G-PDUs from this PFCP-u tunnel, the SMF shall then check if it has an active session for
each received G-PDU packet:
- if so, the SMF shall pe
...

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