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TR 28.836
Study on intent-driven management for Network Slicing

3GPP‑Page  
V18.0.0 (Wzip)2023/12  25 p.
Rapporteur:
Mr. Groenendijk, Jan
Ericsson LM

full Table of Contents for  TR 28.836  Word version:  18.0.0

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0  Introductionp. 6

With the recent introduction of intent driven management a service provider or network operator can manage 5G network and services through the expression of intents (expectations). Network slice requirements are specified in service profile(s) which can be viewed as expectations on a network slice.

1  Scopep. 7

The present document specifies potential use cases, requirements, and solutions for intent driven management for network slicing. The document provides conclusions and recommendations on the next steps in the standardization.

2  Referencesp. 7

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]
TR 21.905: "Vocabulary for 3GPP Specifications".
[2]
TS 28.530: "Management and orchestration; Concepts, use cases and requirements".
[3]
TS 28.531: "Management and orchestration; Provisioning".
[4]
TS 28.541: "Management and orchestration; 5G Network Resource Model (NRM); Stage 2 and stage 3".
[5]
TS 28.312: "Management and orchestration; Intent driven management services for mobile networks"
[6]
TS 23.501: "System Architecture for the 5G System; Stage 2".
[7]
TR 28.912: "Study on enhanced intent driven management services for mobile networks".
[8]
TS 28.536: "Management and orchestration; Management services for communication service assurance; Stage 2 and stage 3".
[9]
TS 28.532: "Management and orchestration; Generic management services".
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3  Definitions of terms, symbols and abbreviationsp. 7

3.1  Termsp. 7

For the purposes of the present document, the terms given in TR 21.905 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.
intent:
expectations including requirements, goals and constraints given to a 3GPP system, without specifying how to achieve them.
network slice:
a logical network that provides specific network capabilities and network characteristics, supporting various service properties for network slice customers.
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3.2  Symbolsp. 8

Void.

3.3  Abbreviationsp. 8

For the purposes of the present document, the abbreviations given in TR 21.905 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.
CRUD
Create, Read, Update, Delete
CSC
Communication Service Customer
CSP
Communication Service Provider
DNN
Data Network Name
NF
Network Function
NSC
Network Slice Customer
NSP
Network Slice Provider
NOP
Network Operator NRF Network Resource Function
S-NSSAI
Single-Network Slice Selection Assistance Information
UPF
User Plane Function
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4  Concepts and Overviewp. 8

4.1  Generalp. 8

Network slicing is one of the key 5G features. The lifecycle of a Network Slice instance can be described by the following: commissioning, operation and decommissioning. Before a NetworkSlice instance can be created there is a preparation phase. The different phases are described in more detail in TS 28.530.
The attributes in ServiceProfile represent the network slice related requirements, and the attributes in SliceProfile represent network slice subnet related requirements. The uses of ServiceProfile and SliceProfile are described in TS 28.531 and TS 28.541.
Copy of original 3GPP image for 3GPP TS 28.836, Fig. 4.1-1: Intent-driven MnS
Figure 4.1-1: Intent-driven MnS
(⇒ copy of original 3GPP image)
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In Intent-driven management, the MnS consumer provides its intent to the MnS producer. The producer of an Intent-driven MnS permits the consumer to manage the service and / or network resources through the use of intents.

4.2  Classification of use cases in TS 28.531p. 8

The use cases for provisioning of a network slice instance and a network slice subnet instance described in TS 28.530 and TS 28.531 are as follows:
  • Create a network slice instance;
  • Activate a network slice instance;
  • De-active a network slice instance;
  • Modify a network slice instance;
  • Terminate a network slice instance;
  • Create a network slice subnet instance;
  • Activate a network slice subnet instance;
  • De-active a network slice subnet instance;
  • Modify a network slice subnet instance;
  • Terminate a network slice subnet instance.
The technical specification TS 28.531 describes specification level use cases related to network slice management and network slice subnet management. Table 4.2-1 provides the classification of those use cases related to network slice instance and network slice subnet management to required management capabilities. The detail information about use cases and management capability supporting the use cases are described in TS 28.531.
Clause Use case Management capabilities required
5.1.1Network slice instance allocationProvisioning of a network slice
5.1.2Network slice instance subnet allocationProvisioning of a network slice subnet
5.1.3Network slice instance deallocationProvisioning of a network slice
5.1.4Network slice subnet instance deallocationProvisioning of a network slice subnet
5.1.5Obtaining network slice subnet instance informationQuery information
5.1.6Network slice feasibility checkProvisioning of a network slice (subnet)
5.1.7Network slice instance activationProvisioning of a network slice
5.1.8Network slice instance deactivationProvisioning of a network slice
5.1.9Network slice instance modificationModification of a network slice
5.1.10Network slice subnet instance activationProvisioning of a network slice subnet
5.1.11Network slice subnet instance deactivationProvisioning of a network slice subnet
5.1.12Network slice subnet instance modificationModification of a network slice subnet
5.1.13Network slice subnet configurationModification of a network slice subnet
5.1.14Exposure of network slice management dataQuery information
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4.3  Background information of Intent-driven management and intent driven management MnSp. 9

The intent driven management solution is specified in TS 28.312 and was introduced in release 17. As described in TS 28.312, an intent specifies expectations including requirements, goals and constraints for a specific service or network management workflow.
As described in clause 4.1.2 of TS 28.312, based on network slice management, an intent can be categorized based on user types as follows:
  • Intent-CSC MnS producer provides intent driven MnS for communication services.
  • Intent-CSP MnS producer provides intent driven MnS for network services.
  • Intent-NOP MnS producer provides intent driven MnS for network equipment.
Similar with the intent types for CSC, CSP and NOP, the TS 28.530 describes roles related to 5G network and network slicing, some examples of roles are:
  • Communication Service Customer (CSC): Uses communication services.
  • Communication Service Provider (CSP): communication service provided by CSP can be built with or without network slice
  • Network Operator (NOP): Designs, builds, and operates networks and provides related services, including network services and network slices.
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4.4  Background information on the 5G features QoS and network slicingp. 10

Intent-driven management solution tries to relieve the consumer of the management system from (artificial) complexity. In the end the consumer of a management system is not interested in instances of IOC like NetworkSlice, which are concepts introduced to manage slices by classical configuration management. Instead, the consumer of a management system wants to request mobile communication for UE -without the need to know about details of the management system.
The management system needs to offer the flexibility as provided by the network architecture described in TS 23.501, while at the same time any request needs to obey to the limitations of the architecture. The following paragraphs give a brief summary of the basic concepts of QoS and slicing which are the basis for intent-driven management of network slices.
The QoS framework (clause 5.7) and network slicing (clause 5.15) are two independent key features of the 3GPP mobile network architecture [6]. According to TS 23.501:
  • One network slice (identified by its S-NSSAI) supports one or more PDU Connectivity Service ("PDU sessions") i.e. services that provide exchange of PDUs between a UE and a data network identified by a DNN.
  • Each PDU connectivity service contains one or more QoS flows, which might be of different QoS characteristics and which all terminate at the same DNN via the same UPF.
  • Each QoS flow is associated to one "requested" QoS profile and additionally might be associated to "alternative" QoS profiles. Depending on the experienced network conditions the network can switch between these QoS profiles.
On the one hand this concept is the basis to use network slices as internal means for the network operator to partition the network in a way, that QoS flows of similar QoS characteristics are grouped to PDU connectivity services that are tagged by the same S-NSSAI. This specific combination of QoS and network slicing results in that network slices as a whole might be optimized for certain traffic, i.e. to optimize certain NF specifically for the assigned traffic and to assign these NF in NRF to the S-NSSAI. An operator might prepare several of such network slices for traffic of different QoS characteristics; Once a customer requests a PDU connectivity service that matches the QoS characteristics of such prepared network slice, the operator assigns the PDU connectivity services to the correspondingly optimized network slice.
On the other hand, the concept offers the flexibility for CSP and NOP to offer to CSCs a dedicated network slice as a product, that carries all PDU connectivity services as the CSC requires, potentially towards different DNNs (e.g., local breakout in the tenants computing centre, public voice to IMS, and towards public internet), while each PDU connectivity service might carry multiple QoS flows of different QoS.
This flexibility enables the CSC to request PDU connectivity services that are terminating at DNN as required by the CSC (e.g. breakout at local UPF) and that carry QoS flows of specific QoS characteristics. Depending on technical bordering conditions of the requested PDU connectivity services and by the business model of CSP and NOP, CSP or NOP might use the S-NSSAI to group PDU connectivity services to network slices.
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4.5  Benefits of intent driven management approach to network slicingp. 10

One of the drivers of adoption of 5G in the Telecoms industry is support for network slicing. The management solution for network slicing enables an operator to provision a network slice, to do fault supervision and performance assurance of a network slice. Over time more features have been specified to make network slice management more efficient and effective, one example is the ability to create and monitor closed control loops that automatically adjust the network resources to assure that the goals specified in a service profile or slice profile are continuously met without manual intervention. The granularity of this solution is that of ServiceProfile/NetworkSlice and SliceProfile/NetworkSliceSubnet, the fulfilment information is reported on the granularity of a ServiceProfile/SliceProfile.
  • Currently the standards support an MnS consumer to request provision of a NetworkSlice or NetworkSliceSubnet using the mechanism in TS 28.531, and to assure the performance using the mechanism in TS 28.536, see reference [8], this means that a consumer handles two separate requests to provision and to assure a NetworkSlice as the consumer does not know the ServiceProfile Id and may not know the NetworkSlice Id both of which are needed as input to closed loop assurance (fulfilment). With the introduction of intent, the consumer can combine the provisioning and assurance requirements in a single request for an intent which contains a combination of a network slice provisioning expectation and a network slice assurance expectation.
  • Allows decoupling the lifecycle management of network slice requirements from the lifecycle management of the actual network slice. This enables MnS consumer to focus on expressing network slicing requirements (and obtain fulfilment information for those requirements), without knowing how to deal with the detailed management of a network slice. The latter is on MnS producer side.
  • With an intent driven management solution, the consumer automatically receives information about the intent fulfilment status which simplifies the interaction with the producer.
  • Simplified approach, allows using one single unified solution to support the wide variety of slice management functionalities which can be fulfilled by different solutions with the existing slicing management approach, including;
    • Network Slice provisioning allocation/deallocation functionality. In existing slicing management approach, this is implemented by (de-)allocateNSI operation or CRUD operations defined in TS 28.531.
    • Network Slice modification, query functionality. In existing slicing management approach, this is implemented by CRUD operation with Network slicing NRM fragment defined in TS 28.532 and TS 28.541.
    • Network Slice SLS assurance functionality. In existing slicing management approach, this is implemented by CRUD operation with Assurance closed control loop NRM fragment defined in TS 28.532 and TS 28.536.
    • Network Slice Feasibility check. In existing slicing management approach, this is implemented by CRUD operation with feasibility check NRM fragment defined in TS 28.532 and TS 28.541.
  • In current TS 28.531 solutions, when the consumer needs to be more aware of concerns such as the timing and sequencing of CM changes required to modify the NetworkSlice or NetworkSliceSubnet requirements. For example, the consumer needs to issue requests to the MnS producer, monitor the results and issue subsequent requests carefully as the producer will initiate each provisioning procedure upon receiving each request.
  • With an intent driven management solution, the consumer does not need to be aware of the underlying provisioning procedures. The consumer simply modifies their requirements, and the producer decides whether and when a provisioning procedure will be initiated. This can provide the convenience and benefit for Intent driven MnS consumer to express and modify the network slice expectations and its interactions provided by a more MnS consumer friendly management capability.
  • The object in case of using the intent interface is the intent's object type, the fulfilment information can be reported at the level that matches the requirements of the MnS consumer at the intent level. This is independent of the internal object type(s) used by the producer to fulfil the intent.
  • For an MnS consumer it is easier to express the network slice expectations including requirements, goals and constraints using the data structures used for intent.
  • An MnS consumer does not have to have the knowledge about the relations between NetworkSlice provisioning and assurance, or between NetworkSliceSubnet provisioning and assurance.
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5  Use cases and potential requirementsp. 12

6  Potential solutionsp. 15

7  Conclusion and Recommendationp. 22

A  Key issuesp. 23

$  Change historyp. 24


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