ETSI TS 128 531 V15.5.0 (2020-01)

TECHNICAL SPECIFICATION
5G;
Management and orchestration;
Provisioning
(3GPP TS 28.531 version 15.5.0 Release 15)

3GPP TS 28.531 version 15.5.0 Release 15 1 ETSI TS 128 531 V15.5.0 (2020-01)

Reference
RTS/TSGS-0528531vf50
Keywords
5G
ETSI
650 Route des Lucioles
F-06921 Sophia Antipolis Cedex - FRANCE

Tel.: +33 4 92 94 42 00  Fax: +33 4 93 65 47 16

Siret N° 348 623 562 00017 - NAF 742 C
Association à but non lucratif enregistrée à la
Sous-Préfecture de Grasse (06) N° 7803/88

Important notice
The present document can be downloaded from:
http://www.etsi.org/standards-search
The present document may be made available in electronic versions and/or in print. The content of any electronic and/or
print versions of the present document shall not be modified without the prior written authorization of ETSI. In case of any
existing or perceived difference in contents between such versions and/or in print, the prevailing version of an ETSI
deliverable is the one made publicly available in PDF format at www.etsi.org/deliver.
Users of the present document should be aware that the document may be subject to revision or change of status.
Information on the current status of this and other ETSI documents is available at
https://portal.etsi.org/TB/ETSIDeliverableStatus.aspx
If you find errors in the present document, please send your comment to one of the following services:
https://portal.etsi.org/People/CommiteeSupportStaff.aspx
Copyright Notification
No part may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying
and microfilm except as authorized by written permission of ETSI.
The content of the PDF version shall not be modified without the written authorization of ETSI.
The copyright and the foregoing restriction extend to reproduction in all media.

© ETSI 2020.
All rights reserved.
DECT™, PLUGTESTS™, UMTS™ and the ETSI logo are trademarks of ETSI registered for the benefit of its Members.

3GPP™ and LTE™ are trademarks of ETSI registered for the benefit of its Members and
of the 3GPP Organizational Partners.
oneM2M™ logo is a trademark of ETSI registered for the benefit of its Members and
of the oneM2M Partners. ®
GSM and the GSM logo are trademarks registered and owned by the GSM Association.
ETSI
3GPP TS 28.531 version 15.5.0 Release 15 2 ETSI TS 128 531 V15.5.0 (2020-01)
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.
Trademarks
The present document may include trademarks and/or tradenames which are asserted and/or registered by their owners.
ETSI claims no ownership of these except for any which are indicated as being the property of ETSI, and conveys no
right to use or reproduce any trademark and/or tradename. Mention of those trademarks in the present document does
not constitute an endorsement by ETSI of products, services or organizations associated with those trademarks.
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
interpreted as being references to the corresponding ETSI deliverables.
The cross reference between 3GPP and ETSI identities can be found under http://webapp.etsi.org/key/queryform.asp.
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
3GPP TS 28.531 version 15.5.0 Release 15 3 ETSI TS 128 531 V15.5.0 (2020-01)
Contents
Intellectual Property Rights . 2
Legal Notice . 2
Modal verbs terminology . 2
Foreword . 6
1 Scope . 7
2 References . 7
3 Definitions and abbreviations . 7
3.1 Definitions . 7
3.2 Abbreviations . 8
4 General . 8
4.1 Overview . 8
4.2 Configuration information for the constituents of an NSI . 10
4.3 General information for network slice instance. 10
4.4 General information for network slice subnet instance . 11
4.5 General information for service profile . 11
4.6 General information for network slice related identifiers . 11
5 Specification level requirements . 13
5.1 Use cases . 13
5.1.1 Network slice instance creation . 13
5.1.2 Network slice subnet instance creation . 14
5.1.3 Network slice instance termination . 16
5.1.4 Network slice subnet instance termination . 17
5.1.5 Obtaining network slice subnet instance information . 18
5.1.6 Network slice feasibility check . 19
5.1.7 Network slice instance activation . 20
5.1.8 Network slice instance deactivation . 20
5.1.9 Network slice instance modification . 21
5.1.10 Network slice subnet instance activation . 22
5.1.11 Network slice subnet instance deactivation . 23
5.1.12 Network slice subnet instance modification . 24
5.1.13 Network slice subnet configuration . 25
5.1.14 Exposure of network slice management data . 25
5.1.15 Exposure of network slice management capability . 26
5.1.16 Network slice subnet instance management capability exposure . 26
5.1.17 Creation of a 3GPP NF . 27
5.1.18 Configuration of a 3GPP NF instance. 28
5.1.19 Creation of a 3GPP sub-network . 29
5.1.20 Configuration of a 3GPP sub-network . 30
5.1.21 Network slice subnet feasibility check. 31
5.1.22 Network slice resource capacity planning . 32
5.1.23 Network slice subnet management with assigned priority . 33
5.1.24 Management interaction with NFV MANO for network service priority . 33
5.2 Requirements . 34
5.2.1 Requirements for network slice provisioning service . 34
5.2.2 Requirements for network slice subnet provisioning service . 34
5.2.3 Requirements for NF provisioning service . 35
5.2.4 Requirements for sub-network provisioning service . 35
6 Management services for provisioning of networks and network slicing . 36
6.1 Management services for network slice provisioning . 36
6.2 Management services for network slice subnet provisioning . 39
6.3 Management services for network function provisioning . 40
6.4 Management services for network and sub-network provisioning . 41
ETSI
3GPP TS 28.531 version 15.5.0 Release 15 4 ETSI TS 128 531 V15.5.0 (2020-01)
6.5. Operations of provisioning . 42
6.5.1 AllocateNsi operation . 42
6.5.1.1 Description . 42
6.5.1.2 Input parameters . 42
6.5.1.3 Output parameters . 43
6.5.2 AllocateNssi operation . 43
6.5.2.1 Description . 43
6.5.2.2 Input parameters . 43
6.5.2.3 Output parameters . 43
6.5.3 DeallocateNsi operation . 43
6.5.3.1 Description . 43
6.5.3.2 Input parameters . 43
6.5.3.3 Output parameters . 44
6.5.4 DeallocateNssi operation . 44
6.5.4.1 Description . 44
6.5.4.2 Input parameters . 44
6.5.4.3 Output parameters . 44
6.5.5 AllocateNetwork operation . 44
6.5.5.1 Description . 44
6.5.5.2 Input parameters . 44
6.5.5.3 Output parameters . 44
7 Provisioning procedures of networks and network slicing . 45
7.1 General . 45
7.2 Procedure of Network Slice Instance Allocation . 45
7.3 Procedure of Network Slice Subnet Instance Allocation . 46
7.4 Procedure of Network Slice Instance Deallocation . 48
7.5 Procedure of Network Slice Subnet Instance Deallocation . 49
7.6 Procedure of Network Slice Instance Modification . 51
7.7 Procedure of Network Slice Subnet Instance Modification . 52
7.8 Procedure of Obtaining Network Slice Subnet Capability . 53
7.8.1 Introduction. 53
7.8.2 Querying Network Slice Subnet Capability Information . 53
7.8.3 Notify Network Slice Subnet Capability Information . 54
7.9 Procedure of TN coordination supporting network slicing . 54
7.9.1 Introduction . 54
7.9.2 Interaction with NFVO as TN Manager . 54
7.10 Procedure of NF instance creation . 55
7.11 Procedure of NF instance modification . 57
7.12 Procedure of NF instance deletion . 57
7.13 Procedure of reservation and checking feasibility of NSI . 58
7.14 Procedure of reservation and checking feasibility of network slice subnet . 59
7.15 Procedure of network slice capacity planning . 60
7.16 Procedure of allocating network with or without slicing for communication services . 62
8 RESTful HTTP-based solution set of provisioning. 63
8.1 Mapping of operations . 63
8.1.1 Introduction. 63
8.1.2 Operation AllocateNsi . 63
8.1.3 Operation AllocateNssi . 63
8.1.4 Operation DeallocateNsi . 64
8.1.5 Operation DeallocateNssi . 64
8.1.6 Operation AllocateNetwork . 64
8.2 Resources . 65
8.2.1 Resource definitions . 65
8.2.1.1 Resource ObjectManagement/NS/ServiceProfiles . 65
8.2.1.1.1 Description . 65
8.2.1.1.2 URI . 65
8.2.1.1.3 HTTP methods . 65
8.2.1.2 Resource ObjectManagement/NSS/SliceProfiles . 66
8.2.1.2.1 Description . 66
8.2.1.2.2 URI . 66
ETSI
3GPP TS 28.531 version 15.5.0 Release 15 5 ETSI TS 128 531 V15.5.0 (2020-01)
8.2.1.2.3 HTTP methods . 66
8.2.1.3 Resource ObjectManagement/ServiceProfiles . 67
8.2.1.3.1 Description . 67
8.2.1.3.2 URI . 67
8.2.1.3.3 HTTP methods . 67
Annex A (informative): Change history . 68
History . 69

ETSI
3GPP TS 28.531 version 15.5.0 Release 15 6 ETSI TS 128 531 V15.5.0 (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 28.531 version 15.5.0 Release 15 7 ETSI TS 128 531 V15.5.0 (2020-01)
1 Scope
The present document specifies use cases, requirements, management services and procedures for provisioning of 5G
networks.
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 28.525: "Telecommunication management; Life Cycle Management (LCM) for mobile
networks that include virtualized network functions; Requirements".
[3] ETSI GS NFV-IFA 013 (V2.4.1) (2018-02): "Network Function Virtualisation (NFV); Release 2;
Management and Orchestration; Os-Ma-nfvo reference point - Interface and Information Model
Specification".
[4] 3GPP TS 28.530: "Management and orchestration; Concepts, use cases and requirements".
[5] 3GPP TS 22.261 "Service requirements for next generation new services and markets".
[6] 3GPP TS 28.541: "Management and orchestration; 5G Network Resource Model (NRM); Stage 2
and stage 3".
[7] 3GPP TS 28.526: "Life Cycle Management (LCM) for mobile networks that include virtualized
network functions; Procedures".
[8] 3GPP TS 28.532: "Management and orchestration; Generic management services".
[9] 3GPP TS 23.501: "Technical Specification Group Services and System Aspects;System
Architecture for the 5G System;Stage 2".
[10] 3GPP TS 38.300: "Technical Specification Group Radio Access Network;NR; NR and NG-RAN
Overall Description;Stage 2".
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the terms and definitions given in TR 21.905 [1], TS 28.530 [4] and the
following apply. A term defined in the present document takes precedence over the definition of the same term, if any,
in TR 21.905 [1] and TS 28.530 [4].

ETSI
3GPP TS 28.531 version 15.5.0 Release 15 8 ETSI TS 128 531 V15.5.0 (2020-01)
3.2 Abbreviations
For the purposes of the present document, the abbreviations given in TR 21.905 [1], TS 28.530 [4] and the following
apply. An abbreviation defined in the present document takes precedence over the definition of the same abbreviation, if
any, in TR 21.905 [1].
5GC 5G Core Network
AMF Access and Mobility Management Function
CSC Communication Service Customer
CSMF Communication Service Management Function
CSP Communication Service Provider
CP Control Plane
IOC Information Object Class
MANO Management and Orchestration
MnS Management Service
NF Network Function
NFV Network Functions Virtualisation
NRM Network Resource Model
NSaaS Network Slice as a Service
NSI Network Slice Instance
NSMF Network Slice Management Function
NSSI Network Slice Subnet Instance
NSSMF Network Slice Subnet Management Function

TN Transport Network
VNF Virtualized Network Function
UP User Plane
4 General
4.1 Overview
5G system consists of 5G Access Network (AN), 5G Core Network (5GC). Network slicing is one of 5G key features.
The management aspects of a Network Slice Instance (NSI) are described by the four phases shown in Figure 4.3.1.1 of
TS 28.530 [4].
The provisioning of network slicing includes the four phases which are preparation, commissioning, operation and
decommissioning:
- In the preparation phase the NSI does not exist. The preparation phase includes network slice design, on-
boarding, evaluation of the network slice requirements, preparing the network environment and other necessary
preparations required to be done before the creation of an NSI.
- During the NSI lifecycle stage which include commissioning phase, operation phase and decommissioning
phase, the NSI provisioning operations include:
- Create an NSI;
- Activate an NSI;
- De-active an NSI;
- Modify an NSI;
- Terminate an NSI.
The operations of the provisioning of an NSI occurs during different phases of a NSI:
a) During the commissioning phase:
ETSI
3GPP TS 28.531 version 15.5.0 Release 15 9 ETSI TS 128 531 V15.5.0 (2020-01)
- Create an NSI.
During NSI creation all resources to the NSI have been created and configured to satisfy the network slice
requirements. NSI creation may trigger NSSI(s) creation or using existing NSSI(s) and setting up the
corresponding associations.
b) During the operation phase:
- Activate an NSI;
- Modify an NSI;
- De-active an NSI.
NSI activation includes any actions that make the NSI active to provide communication services. NSI activation
may trigger NSSI activation.
NSI modification in operation phase could map to several workflows, e.g. changes of NSI capacity, changes of
NSI topology, NSI reconfiguration. NSI modification can be triggered by receiving new network slice related
requirements, new communication service requirements, or the result of NSI supervision automatically. NSI
modification may trigger NSSI modification.
The NSI deactivation operation may be needed before NSI modification operation and the NSI activation
operation may be needed after the NSI modification operation. NSI deactivation includes any actions that make
the NSI inactive and not providing any communication services. NSI deactivation trigger NSSI deactivation to
deactivate constituent NSSI(s) which is not used by other NSI(s). Operator may decide to keep the NSI without
termination after deactivation and reactivate it when receives new communication service request.
c) During the decommissioning phase:
- Terminate an NSI.
NSI termination step includes any action that make the NSI does not exist anymore and release resources that are
not used by other NSI(s). NSI termination may trigger NSSI termination to terminate constituent NSSI(s) which
is not used by other NSI(s).
Similarly, provisioning for network slice subnet instance includes the following operations:
- Create an NSSI;
- Activate an NSSI and associate it with certain NSI to be used by the NSI;
- Disassociate the NSSI with certain NSI and de-active the NSSI if it’s not associated with any NSI;
- Modify an NSSI;
- Terminate an NSSI.
The following are NSSI states:
NSSI_NULL – the NSSI does not exist
NSSI_NOT_IN_USE – the NSSI exists, but is not used by (associated with) any NSI or NSSI
NSSI_IN_USE – the NSSI is used by (associated with) at least one NSI or at least one NSSI
The following is the state diagram:
ETSI
3GPP TS 28.531 version 15.5.0 Release 15 10 ETSI TS 128 531 V15.5.0 (2020-01)
NSSI_NULL
Terminate
Create
Modify NSSI_NOT_IN_USE
Associate
Modify
NSSI_IN_USE
Associate
Deassociate
Used by any NSI or other
NSSI?
Yes
No
Figure 4.1-1
4.2 Configuration information for the constituents of an NSI
To use network slice to support communication service or deliver a network slice as a service, the 3GPP defined
constituents of the NSI should be configured by 3GPP management system according to the types and requirements of
the network slice so that the NSI can be operated and maintained.
The configuration information of these components may include:
- Information on the requirements to be applied to every NSI constituent to satisfy the requirements of multiple
NSIs if the constituent is shared by multiple NSIs;
- Network function selection information: Information on the selection of the NFs (e.g., AMF) according to the
requirements of this NSI;
- Connection information: The information of the logical links to carry the NSI’s CP and UP data between the
component and other NFs and NSSIs belonging to the NSI.
NOTE 1: The list of information above is not exhaustive.
NOTE 2: The list of information above is not all necessary for an NSI.
4.3 General information for network slice instance
The general information used to describe network slice instance may include:
- Resource model information, which describes the static parameters and functional components of network slice,
includes service profile, network slice type (e.g. eMBB), additional system feature (e.g. multicast, Edge
Computing), priority.
ETSI
3GPP TS 28.531 version 15.5.0 Release 15 11 ETSI TS 128 531 V15.5.0 (2020-01)
- Management model information, which describes the information model that is used for network slice lifecycle
management, includes configuration profile (e.g. application configuration parameters).
- Capability model information, which describes the capability including supported communication service
characteristic information (e.g. service type, UE mobility level, density of users, traffic density), QoS attributes
(e.g. bandwidth, latency, throughput and so on) and capacity (e.g. maximum number of UEs), can be exposed to
CSC via CSMF.
4.4 General information for network slice subnet instance
The general information used to describe network slice subnet instance may include:
- Resource model information, which describes the static parameters and functional component of network slice
subnet, includes slice profile, network slice subnet type (e.g. RAN eMBB, CN eMBB), additional system feature
(e.g. multicast, Edge Computing), priority, QoS attributes (e.g. bandwidth, latency, number of subscribers and so
on), NSD ID.
- Management model information, which describes the information model that is used for network slice subnet
lifecycle management, includes configuration profile (e.g. application configuration parameters).
- Capability model information, which describes the capability including supported communication service
characteristic information (e.g. service type, UE mobility level, density of users, traffic density), QoS attributes
(e.g. bandwidth, latency, throughput and so on) and capacity (e.g. maximum number of UEs).
4.5 General information for service profile
Depending on industry requirements and operator’s design requirements, different service profiles may be used to
represent SLS associated with instances of Network Slice IOC.
The following are examples for service profile:
- A service profile is used to capture a set of requirements for the new network slice instance such as (i.e. eMBB,
MIoT, URLLC).
- A service profile is used to capture a set of specific industry requirements for creation of network slice instance
such as (e.g. V2X, smart grid, Remote Healthcare).
4.6 General information for network slice related identifiers
There are following network slice related identifiers which serve different purposes:
Identifier Description
Identifiers for network slice management purpose
NetworkSlice Represent the management identifier of network slice instance. Management identifier
identifier of network slice instance is defined in TS 28.541[6] as objectinstance attribute of
NetworkSlice IOC.
NetworkSliceSubnet
Represent the management identifier for a network slice subnet instance. Management
identifier
identifier of network slice subnet instance is defined in TS 28.541[6] as objectinstance
attribute of NetworkSliceSubnet IOC.
Identifiers for network slice selection purpose
NSI ID Represent Core Network part of a Network Slice instance when multiple Network Slice
instances of the same Network Slice are deployed, and there is a need to differentiate
between them in the 5GC. Referred to TS 23.501[9].
S-NSSAI Represent network slice. Referred to TS 23.501[9] and TS 38.300[10].
ETSI
3GPP TS 28.531 version 15.5.0 Release 15 12 ETSI TS 128 531 V15.5.0 (2020-01)
PLMN ID Represent PLMN identifier.

The NSI ID and S-NSSAI are configured by the management system.

ETSI
3GPP TS 28.531 version 15.5.0 Release 15 13 ETSI TS 128 531 V15.5.0 (2020-01)
5 Specification level requirements
5.1 Use cases
5.1.1 Network slice instance creation
<>
Use case stage Evolution/Specification
Related use
Goal To satisfy request for allocation of a network slice instance with certain
characteristics, by creation of new or using existing network slice instance; the
request includes the network slice related requirements.
Actors and Roles CSMF, who acts as an example of network slice management service consumer.
NOP operator
Telecom Network slice instance
resources Network slice subnet instance
Transport network
NSMF, who acts as an example of network slice management service provider.
NSSMF, who acts as an example of network slice subnet management service
provider.
Assumptions
N/A
Pre-conditions N/A
Begins when NSMF receives the request for allocation of the network slice instance with
certain characteristics; the request contains network slice related requirements
and the information indicating whether the requested NSI could be shared with
other consumers.
Step 1 (M) If the requested NSI can be shared and if an existing NSI can be used, the NSMF
decides to use the existing NSI.
Modification of the existing NSI may be needed to satisfy the network slice
instance related requirements. Use case is completed go to “Step 8".
Otherwise, the NSMF triggers to create a new NSI, for which the following steps 2
– 8 are needed.
Step 2 (M)
NSMF decides on the constituent NSSIs and the topology of the NSI to be
created using the information from service profile [6]. For the constituent NSSIs,
the NSMF derives network slice subnet related requirements from the network
slice related requirements. If reconfiguration of the transport network is needed,
the NSMF derives transport network related requirements (e.g. latency,
bandwidth) from the network slice related requirements.
Step 3 (M) For the required NSSI(s), the NSMF sends network slice subnet related Network slice
requirements to the NSSMF to request allocation of the required NSSI(s). subnet
instance
creation use
case
Step 4 (M) NSMF receives the information of the allocated NSSI(s) (e.g. the management
identifier of NSSI, service access point information of NSSI, external connection
point information of NSSI) from NSSMF.
Step 5 (M) NSMF, via NSSMF, sends the transport network related requirements (e.g.
external connection point, latency and bandwidth) to the TN Manager. The TN
manager reconfigures the TN accordingly and responds to the NSMF via NSSMF.
Step 6 (M)
NSMF receives the response from TN Manager via NSSMF.
Step 7 (M)
NSMF associates the NSSI(s) with the corresponding NSI (e.g. allocation of the
management identifier of NSI and mapping the management identifier of NSI with
the received management Identifier of NSSI(s)) and triggers to establish the links
between the service access points of the NSSI(s).
Step 8 (M) NSMF notifies the network slice instance information of NSI (e.g., the
management identifier of NSI).
Ends when
All the steps identified above are successfully completed.
Exceptions One of the steps identified above fails.
Post-conditions An NSI is ready to satisfy the network slice related requirements.
Traceability REQ-PRO_NSSI-FUN-1, REQ-PRO_NSI-FUN-3.

ETSI
3GPP TS 28.531 version 15.5.0 Release 15 14 ETSI TS 128 531 V15.5.0 (2020-01)
5.1.2 Network slice subnet instance creation
ETSI
3GPP TS 28.531 version 15.5.0 Release 15 15 ETSI TS 128 531 V15.5.0 (2020-01)
<>
Use case stage Evolution/Specification
Related use
Goal Create a new network slice subnet instance or use an existing network slice
subnet instance to satisfy the network slice subnet related requirements; provide
the provisioning service consumer with identity of the NFVO which the consumer
can use for further access to the information of the involved VNFs, PNFs and
NSs.
Actors and Roles NSMF, who acts as an example of network slice subnet management service
consumer.
Telecom Network Slice Subnet instance
resources Network Service instance
NSSMF, who acts as an example of network slice subnet management service
provider.
The operator deployed NFVO to manage the lifecycle of VNFs and
interconnection between the VNFs and PNFs in terms of the NS instances.
Assumptions
Network slice subnet instance may include network functions which are
virtualized.
Pre-conditions VNF Packages for virtualized network functions to be included in the network
slice subnet instance have been already on-boarded.
Begins when The NSMF sends to the NSSMF a request for a NSSI to be associated with the
NSI; the request contains network slice subnet related requirements including the
SliceProfile [6].
NSSMF receives request for a network slice subnet instance. The request
contains network slice subnet related requirements. The request may include
guidance for use of particular NFVO(s) when VNFs and PNFs in certain part of
the network are involved. The request may also include query of the identity of
the NFVO to be used.
Step 1 (M) Based on the network slice subnet related requirements received, NSSMF
decides to create a new NSSI or use an existing NSSI.
Step 2 (M) If an existing network slice subnet instance is decided to be used, NSSMF may
trigger to modify the existing network slice subnet instance to satisfy the network
slice subnet related requirements. Go to “Step 8”.
Otherwise, NSSMF triggers to create a new NSSI, the following steps are
needed.
Step 3 (O)
If the required NSSI contains constituent NSSI(s) managed by other NSSMF(s),
the first NSSMF derives the requirements for the constituent NSSI(s) and sends
those requirements to the corresponding NSSMF(s) which manages the
constituent NSSI(s).
The first NSSMF receives the constituent NSSI information from the other
NSSMF(s) and associates the constituent NSSI(s) with the required NSSI.
Step 4 (M) Based on the network slice subnet related requirements received and SliceProfile
[6], the NSSMF decides that to satisfy the NSSI requirements, the part of the
network controlled by certain NFVO should be involved. The NSSMF determines
the NS related requirements (i.e. information about the target NSD and additional
parameterization for the specific NS to instantiate, see clause 7.3.3 in ETSI GS
NFV-IFA013 [3]).
Step 5 (M) Based on the NS related requirements, NSSMF triggers corresponding NS TS 28.525 [2]
instantiation request to NFVO via Os-Ma-nfvo interface as described in clause Clause 6.4.3
6.4.3 in TS 28.525 [2], and the NFVO performs NS instantiation. (see note) NS instance
use cases
Step 6 (M) NSSMF associates the NS instance with corresponding network slice subnet
instance (e.g. allocation of the management identifier of NSSI and mapping with
the corresponding identifiers).
Step 7 (M) NSSMF is using the NF provisioning service to configure the NSSI constituents. NF
In case of RAN NSSI, the configuration contains RRM policy information for provisioning
individual Radio cells. In the cells shared by multiple NSSIs such policy includes service
guidance for split of Radio resources between the NSSIs.
Step 8 (M) NSSMF notifies the provisioning service consumer with the NSSI information (e.g.
the management identifier of NSSI) and the NFVO identity when relevant. The
NSMF associates the NSSI with the NSI.
Ends when All the steps identified above are successfully completed.
Exceptions
One of the steps identified above fails.
Post-conditions A NSSI is ready to satisfy the network slice subnet related requirements.
Traceability REQ-PRO_NSSI-FUN-2, REQ-PRO_NSSI-FUN-3, REQ-PRO_NSSI-FUN-4,
REQ-PRO_NSSI-FUN-5, REQ-PRO_NSSI-FUN-6, REQ-PRO_NSSI-FUN-14.
NOTE: According to the TS 28.525 [2], for the PNFs, NS instantiation includes only establishment of interconnection
with other NFs.
ETSI
3GPP TS 28.531 version 15.5.0 Release 15 16 ETSI TS 128 531 V15.5.0 (2020-01)

5.1.3 Network sl
...