ETSI GR NFV-EVE 012 V3.1.1 (2017-12)

Network Functions Virtualisation (NFV) Release 3; Evolution and Ecosystem; Report on Network Slicing Support with ETSI NFV Architecture Framework

DGR/NFV-EVE012

General Information

• Status: Published
• Publication Date: 20-Dec-2017
• Technical Committee: NFV EVE - Evolution and Ecosystem
• Current Stage: 12 - Completion
• Due Date: 08-Jan-2018
• Completion Date: 21-Dec-2017

Standards Content (Sample)

GROUP REPORT
Network Functions Virtualisation (NFV) Release 3;
Evolution and Ecosystem;
Report on Network Slicing Support
with ETSI NFV Architecture Framework
Disclaimer
The present document has been produced and approved by the Network Functions Virtualisation (NFV) ETSI Industry
Specification Group (ISG) and represents the views of those members who participated in this ISG.
It does not necessarily represent the views of the entire ETSI membership.

2 ETSI GR NFV-EVE 012 V3.1.1 (2017-12)

Reference
DGR/NFV-EVE012
Keywords
network, NFV, slicing
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3 ETSI GR NFV-EVE 012 V3.1.1 (2017-12)
Contents
Intellectual Property Rights . 5
Foreword . 5
Modal verbs terminology . 5
1 Scope . 6
2 References . 6
2.1 Normative references . 6
2.2 Informative references . 6
3 Definitions and abbreviations . 7
3.1 Definitions . 7
3.2 Abbreviations . 8
4 Overview of network slicing . 8
4.1 Introduction . 8
4.2 Concepts defined by SDOs and Fora and NFV architectural framework mapping . 8
4.2.1 Potential relevant SDOs and Fora . 8
4.2.2 NGMN . 10
4.2.2.1 Network slicing as defined by NGMN . 10
4.2.3 3GPP . 11
4.2.3.1 Network slicing as defined by 3GPP . 11
4.2.3.2 Mapping NFV and 3GPP network slicing concepts . 12
4.2.3.2.1 Network slice vs. Network service . 12
4.2.3.2.2 Architecture . 12
4.2.3.2.3 Network slice lifecycle management . 14
4.2.4 ONF . 14
4.2.4.1 Network slicing abstraction and resource control from the ONF perspective . 14
4.2.4.2 Mapping NFV and ONF SDN architecture network slicing concepts . 16
4.3 NFV and SDN relation in multi-tenant and multi-domain environments . 16
5 Use cases analysis . 18
5.1 Introduction . 18
5.2 Use case 1: Single operator domain network slice . 18
5.2.1 Description . 18
5.2.2 Security implication . 19
5.2.3 Reliability implication . 19
5.2.4 Relation to NFV constructs . 19
5.2.5 Potential impact to the NFV architectural framework . 19
5.3 Use case 2: Network Slice Instance creation . 20
5.3.1 Description . 20
5.3.2 Security implication . 20
5.3.3 Reliability implication . 20
5.3.4 Relation to NFV constructs . 21
5.3.5 Potential impact to the NFV architectural framework . 21
5.4 Use case 3: Network Slice Subnet Instance creation . 21
5.4.1 Description . 21
5.4.2 Security implication . 21
5.4.3 Reliability implication . 21
5.4.4 Relation to NFV constructs . 22
5.4.5 Potential impact to the NFV architectural framework . 22
5.5 Use case 4: Network Slice Instance creation, configuration and activation with VNFs . 22
5.5.1 Description . 22
5.5.2 Security implication . 22
5.5.3 Reliability implication . 22
5.5.4 Relation to NFV constructs . 22
5.5.5 Potential impact to the NFV architectural framework . 22
5.6 Use case 5: Priority of NSI for re-allocating the limited resources . 22
5.6.1 Description . 22
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4 ETSI GR NFV-EVE 012 V3.1.1 (2017-12)
5.6.2 Security implication . 23
5.6.3 Reliability implication . 23
5.6.4 Relation to NFV constructs . 23
5.6.5 Potential impact to the NFV architectural framework . 23
5.7 Use case 6: Network Slice as a Service . 23
5.7.1 Description . 23
5.7.2 Security implication . 23
5.7.2.0 Introduction . 23
5.7.2.1 Network service level . 24
5.7.2.2 VNF level . 24
5.7.3 Reliability implication . 26
5.7.4 Relation to NFV constructs . 26
5.7.5 Potential impact to the NFV architectural framework . 26
5.8 Use case 7: Network Slice Instance across multiple operators . 27
5.8.1 Description . 27
5.8.2 Security implication . 27
5.8.3 Reliability implication . 27
5.8.4 Relation to NFV constructs . 27
5.8.5 Potential impact to the NFV architectural framework . 27
6 Support of network slicing . 27
6.1 Recommendation: Architectural framework . 27
6.1.0 Introduction. 27
6.1.1 Reference points and/or interfaces . 27
6.1.2 Functional . 28
6.1.3 Descriptors . 28
6.2 Recommendation: Security . 28
6.2.0 Introduction. 28
6.2.1 Network service level . 28
6.2.2 VNF level . 29
6.3 Recommendation: Reliability . 29
6.4 Relation with ETSI ISG NFV group specifications . 29
7 Conclusion . 31
Annex A: Authors & contributors . 32
Annex B: Change History . 34
History . 35

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5 ETSI GR NFV-EVE 012 V3.1.1 (2017-12)
Intellectual Property Rights
Essential patents
IPRs essential or potentially essential to the present document 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
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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
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.
Foreword
This Group Report (GR) has been produced by ETSI Industry Specification Group (ISG) Network Functions
Virtualisation (NFV).
Modal verbs terminology
In the present document "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.

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6 ETSI GR NFV-EVE 012 V3.1.1 (2017-12)
1 Scope
The present document analyses use cases related to network slicing as defined in SDOs and industry fora. Furthermore,
the present document describes how these use cases could be mapped to the current NFV concepts and supported by the
ETSI NFV architectural framework [i.2] and by NFV-MANO [i.10].
2 References
2.1 Normative references
Normative references are not applicable in the present document.
2.2 Informative references
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
referenced document (including any amendments) applies.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
The following referenced documents are not necessary for the application of the present document but they assist the
user with regard to a particular subject area.
[i.1] ETSI GR NFV 001 (V1.2.1) (05-2017): "Network Functions Virtualisation (NFV); Use Cases".
[i.2] ETSI GS NFV 002 (V1.2.1) (12-2014): "Network Functions Virtualisation (NFV); Architectural
Framework".
[i.3] ETSI GS NFV 003 (V1.2.1) (12-2014): "Network Functions Virtualisation (NFV); Terminology
for Main Concepts in NFV".
[i.4] ETSI GS NFV-EVE 005 (V1.1.1) (12-2015): "Network Functions Virtualisation (NFV);
Ecosystem; Report on SDN Usage in NFV Architectural Framework".
[i.5] ETSI GS NFV-IFA 009: "Network Functions Virtualisation (NFV); Management and
Orchestration; Report on Architectural Options".
[i.6] ETSI GS NFV-IFA 013 (V2.1.1) (10-2016): "Network Functions Virtualisation (NFV);
Management and Orchestration; Os-Ma-Nfvo reference point - Interface and Information Model
Specification".
[i.7] ETSI GS NFV-IFA 014 (V2.3.1) (08-2017): "Network Functions Virtualisation (NFV) Release 2;
Management and Orchestration; Network Service Templates Specification".
[i.8] ETSI GR NFV-IFA 022 (V0.8.1): "Network Functions Virtualisation (NFV) Release 3;
Management and Orchestration; Report on Management and Connectivity for Multi-Site
Services".
[i.9] ETSI GR NFV-IFA 028 (V0.13.0): "Network Functions Virtualisation (NFV) Release 3;
Management and Orchestration; Report on architecture options to support multiple administrative
domains".
[i.10] ETSI GS NFV-MAN 001 (V1.1.1) (12-2014): "Network Functions Virtualisation (NFV);
Management and Orchestration".
[i.11] ETSI GR NFV-REL 007 (V1.1.1) (09-2017): "Network Functions Virtualisation (NFV);
Reliability; Report on the resilience of NFV-MANO critical capabilities".
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[i.12] ETSI GS NFV-SEC 009 (V1.2.1) (12-2016): "Network Functions Virtualisation (NFV); NFV
Security; Report on use cases and technical approaches for multi-layer host administration".
[i.13] ETSI GS NFV-SEC 012 (V3.1.1) (01-2017): "Network Functions Virtualisation (NFV) Release 3;
Security; System architecture specification for execution of sensitive NFV components".
[i.14] NGMN Alliance: "Description of Network Slicing Concept", January 2016.
[i.15] NGMN Alliance: "5G security recommendations; Package #2: Network Slicing", April, 2016.
[i.16] ONF TR-521: "SDN Architecture", Issue 1.1, February 2016.
[i.17] ONF TR-526: "Applying SDN architecture to 5G slicing", Issue 1, April 2016.
[i.18] ONF TR 527: "Functional Requirements for Transport API", June 2016.
[i.19] ONF TR-540: "Orchestration: A More Holistic View", January 2017.
[i.20] 3GPP TS 22.261 (V15.2.0) (09-2017): "Service requirements for next generation new services and
markets".
[i.21] 3GPP TR 28.801 (V15.0.0) (09-2017): "Telecommunication management; Study on management
and orchestration of network slicing for next generation network".
[i.22] ETSI GS NGP 001: "Next Generation Protocol (NGP); Scenario Definitions".
[i.23] ETSI GS NFV-IFA 005: "Network Functions Virtualisation (NFV); Management and
Orchestration; Or-Vi reference point - Interface and Information Model Specification".
[i.24] ETSI GS NFV-IFA 006: "Network Functions Virtualisation (NFV); Management and
Orchestration; Vi-Vnfm reference point - Interface and Information Model Specification".
[i.25] ETSI GS NFV-IFA 008: "Network Functions Virtualisation (NFV); Management and
Orchestration; Ve-Vnfm reference point - Interface and Information Model Specification".
[i.26] ETSI GS NFV-IFA 012: "Network Functions Virtualization (NFV) Release 3; Management and
Orchestration; Os-Ma-Nfvo reference point - Application and Service Management Interface and
Information Model Specification".
[i.27] ETSI GS NFV-IFA 010: "Network Functions Virtualisation (NFV); Management and
Orchestration; Functional requirements specification".
[i.28] ETSI GS NFV-IFA 011: "Network Functions Virtualisation (NFV); Management and
Orchestration; VNF Packaging Specification".
[i.29] 3GPP TR 23.799: "Study on Architecture for Next Generation System".
[i.30] 3GPP TS 23.501: "System Architecture for the 5G System".
[i.31] 3GPP TS 23.502: "Procedures for the 5G System".
[i.32] 3GPP TR 33.899: "Study on the security aspects of the next generation system".
[i.33] 3GPP TS 28.531: "Provisioning of network slicing for 5G networks and services".
[i.34] 3GPP TS 28.530: "Management of network slicing in mobile networks; Concepts, use cases and
requirements".
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the terms and definitions given in ETSI GS NFV 003 [i.3] apply.
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8 ETSI GR NFV-EVE 012 V3.1.1 (2017-12)
3.2 Abbreviations
For the purposes of the present document, the abbreviations given in ETSI GS NFV 003 [i.3] and the following apply:
3GPP 3rd Generation Partnership Project
5G Fifth Generation
AN Access Network
CN Core Network
CSMF Communication Service Management Function
HMEE Hardware-Mediated Execution Enclave
NF Network Function
NGMN Next Generation Mobile Networks
NGP Network Generation Protocols
NS Network Service
NSI Network Slice Instance
NSM Network Slice Manager
NSMF Network Slice Management Function
NSSI Network Slice Subnet Instance
NSSMF Network Slice Subnet Management Function
NST Network Slice Template
OAM Operations and Management
ONF Open Networking Foundation
QoS Quality of Service
SDN Software Defined Networking
SDO Standards Development Organisation
TN Transport Network
4 Overview of network slicing
4.1 Introduction
Network slicing is defined by multiple SDOs and Fora. However, the meaning and understanding of the network slicing
concept are different from each other and there is no common definition. The present document does not define network
slicing use cases or features but references external SDOs and Fora's definition and concept of network slicing within
the context of each individual SDO/Fora.
Clause 4.2 shows relevant external body's documents which introduce and define network slicing, and describes related
details provided in NGMN, 3GPP, and ONF. It also describes the possible relationship with the NFV constructs.
Clause 4.3 describes NFV and SDN relation in a multi-tenant and multi-domain environment in term of network slice
deployment.
4.2 Concepts defined by SDOs and Fora and NFV architectural
framework mapping
4.2.1 Potential relevant SDOs and Fora
Table 4.2.1-1 describes relevant SDOs and Fora and their documentation which introduce and define the concept of
network slicing.
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9 ETSI GR NFV-EVE 012 V3.1.1 (2017-12)
Table 4.2.1-1: Relevant external bodies' documents
External
Body Relation to NFV ISG
Title of Document Current Relation to
(Upstream, Area Scope support to Network
or Activity Status Network Slicing
User, or Slicing
Both)
Introduces network
slicing, named as
5G slicing in 5G
white paper, for
purposes of
flexibility,
High level 5G white paper
NGMN 5G white paper Published management and
requirements from NGMN
orchestration.
Needs
standardization
phase to support
those motivations
and requirements.
NGMN white paper
White paper NGMN white
High level describing network
NGMN description of paper for Published
requirements slicing for service
network slicing network slicing
provider networks.
Generic
requirements for
Network slice
Applying SDN SDNizing SDN-based network
abstraction for
Architecture to 5G network slicing for 5G
ONF sustainability Published
Slicing (ONF slicing for 5G services including
and business
TR-526 [i.17]) services orchestration for
agility
holistic operations
[i.19].
Network architecture
including network
entity and UE. Key
issues identified by
3GPP SA2 to
address network
slicing selection,
Study on isolation, roaming
Architecture for Network slice and security as well
High level
3GPP SA2 Next Generation related Published as some examples.
requirements
System (3GPP functionality 3GPP SA2 specifies
TR 23.799 [i.29]) network slicing
concept and
network architecture
and does not have
direct relation to
virtualisation and
MANO work in ISG
NFV.
Definition,
identification,
selection,
subscription,
configuration and
storage aspects of
System network slicing.
Network slice
Architecture for the Architectural Work in High level
3GPP SA2 related
5G System (3GPP requirements progress functionality for
functionality
TS 23.501 [i.30]) network slicing, and
network slicing
supported by the
architecture
including roaming
and non-roaming
scenarios.
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External
Body Relation to NFV ISG
Title of Document Current Relation to
(Upstream, Area Scope support to Network
or Activity Status Network Slicing
User, or Slicing
Both)
Procedures
Procedures
description and
Procedures for the and flows of Network slice
Work in aspects of
3GPP SA2 5G System (3GPP the related
progress supporting network
TS 23.502 [i.31]) architectural procedures
slicing in the 5G
elements
system.
Study work in 3GPP
Study on the
SA3 including
security aspects of
High level Network slice Work in security areas and
3GPP SA3 the next generation
requirements related security progress high level security
system (3GPP
requirements related
TR 33.899 [i.32])
to network slicing.
May be relevant to
Study on Study work in 3GPP
ETSI
management and SA5 on
GS NFV-IFA 008 [i.25],
orchestration of High level Network slice management and
3GPP SA5 Published ETSI
network slicing requirements management orchestration of
GS NFV-IFA 013 [i.6],
(3GPP network slicing in
and ETSI
TR 28.801 [i.21]) mobile networks.
GS NFV-IFA 014 [i.7].
Work item in 3GPP
SA5 on network
Provisioning of Detailed
slice provisioning May be relevant to ETSI
network slicing for specification
Network slice Work in which includes GS NFV-IFA 013 [i.6]
3GPP SA5 5G networks and of network
management progress service provisioning and ETSI
services (3GPP slice
related information GS NFV-IFA 014 [i.7].
TS 28.531 [i.33]) provisioning
model and NST
specification.
Work item in 3GPP
Management of
SA5 on network
network slicing in
Detailed slice management
mobile networks - May be relevant to ETSI
specification which specifies the
concepts, use Network slice Work in GS NFV-IFA 013 [i.6],
3GPP SA5 of network management related
cases and management progress ETSI
slice use cases and
requirements GR NFV-IFA 022 [i.8]
requirements requirements of
(3GPP
3GPP
TS 28.530 [i.34])
TR 28.801 [i.21].
Specify the key
Next Generation
scenarios for the
Protocols (NGP);
ETSI ISG High level Key scenarios NGP, including the
Scenarios Frozen
NGP requirements for the NGP network slicing use
Definitions (ETSI
case of network
GS NGP 001 [i.22])
virtualisation.
4.2.2 NGMN
4.2.2.1 Network slicing as defined by NGMN
According to clause 4 of the NGMN's White Paper [i.14], a Network Slice Instance (NSI) may be composed by none,
one or more Network Slice Subnet Instance (NSSI), which may be shared by another NSI. Similarly, the NSSI is
formed of a set of Network Functions, which can be either VNFs or PNFs.
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Figure 4.2.2.1-1: Network slice conceptual outline
(figure 1 in NGMN White Paper [i.14])
4.2.3 3GPP
4.2.3.1 Network slicing as defined by 3GPP
According to clause 4.2.1 of 3GPP TR 28.801 [i.21], the network slice concept includes the following aspects:
1) Completeness of an NSI:
- An NSI is complete in the sense that it includes all functionalities and resources necessary to support
certain set of communication services thus serving certain business purpose.
2) Components of an NSI:
- The NSI contains NFs (e.g. belonging to AN and CN).
- If the NFs are interconnected, the 3GPP management system contains the information relevant to the
connections between these NFs such as topology of connections, individual link requirements (e.g. QoS
attributes), etc.
- For the part of the TN (Transport Network) supporting connectivity between the NFs, the 3GPP
management system provides link requirements (e.g. topology, QoS attributes) to the management
system that handles the part of the TN supporting connectivity between the NFs.
3) Resources used by the NSI:
- The NSI is realized via the required physical and logical resources.
4) Network Slice Template:
- The network slice is described by a Network Slice Template (NST). The NSI is created using the NST
and instance-specific information.
5) NSI policies and configurations:
- Instance-specific policies and configurations are required when creating an NSI.
- Network characteristics examples are ultra-low-latency, ultra-reliability, etc.
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- NSI contains a Core Network part and an Access Network part.
6) Isolation of NSIs:
- A NSI may be fully or partly, logically and/or physically, isolated from another NSI.
4.2.3.2 Mapping NFV and 3GPP network slicing concepts
4.2.3.2.1 Network slice vs. Network service
3GPP TR 28.801 [i.21] describes an information model where a network slice contains one or more network slice
subnets, each of which in turn contains one or more network functions and can also contain other network slice subnets
(see left-hand side of figure 4.2.3.2-1). These network functions can be managed as VNFs and/or PNFs. An NFV
Network Service (NS) can thus be regarded as a resource-centric view of a network slice, for the cases where a Network
Slice Instance (NSI) would contain at least one virtualised network function.
According to 3GPP TR 28.801 [i.21], a network slice subnet instance (NSSI) can be shared by multiple NSIs. The
virtualised resources for the slice subnet and their connectivity to physical resources can be represented by the nested
NS concept defined in ETSI GS NFV-IFA 014 [i.7] (see right-hand side of figure 4.2.3.2-1), or one or more VNFs and
PNFs directly attached to the NS used by the network slice. The dotted arrows in figure 4.2.3.2-1 illustrate this
correspondence from a resource point of view.
NOTE: ETSI ISG NFV does not handle the:
Application-aware NS configuration and management; and
VNF application layer configuration and management; and
Management and deployment of PNFs, or their application layer configuration and management.

Figure 4.2.3.2-1: Relating the information models
4.2.3.2.2 Architecture
3GPP TR 28.801 [i.21] identifies 3 management functions related to network slicing management:
• Communication Service Management Function (CSMF): this function is responsible for translating the
communication service related requirement to network slice related requirements. The CSMF communicates
with the Network Slice Management Function (NSMF).
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• Network Slice Management Function (NSMF): this function is responsible for the management (including
lifecycle) of NSIs. It derives network slice subnet related requirements from the network slice related
requirements. NSMF communicates with the NSSMF and the CSMF.
• Network Slice Subnet Management Function (NSSMF). This function is responsible for the management
(including lifecycle) of NSSIs. The NSSMF communicates with the NSMF.
As shown in figure 4.2.3.2.2-1, the Os-Ma reference point can be used for the interaction between 3GPP slicing related
management functions and NFV-MANO. To properly interface with NFV-MANO, the NSMF and/or NSSMF need to
determine the type of NS or set of NSs, VNF and PNF that can support the resource requirements for a NSI or NSSI,
and whether new instances of these NSs, VNFs and the connectivity to the PNFs need to be created or existing instances
can be re-used.
NOTE 1: In order to use the NS, the NSMF and/or NSSMF would have to maintain an association between
Network Slice Templates (NSTs), and NFV Network Service Descriptors (NSDs) with applicable
deployment flavour identifiers, as well as an association between NSI identifiers and NS instance
identifiers.
NOTE 2: The 3GPP slice-related management functions are still under definition in 3GPP SA5 and future updates
might require further analysis about the interaction between 3GPP slicing related management functions
and NFV-MANO.
Figure 4.2.3.2.2-1: Network slice management in an NFV framework
From a resource management viewpoint, NSI can be mapped to an instance of a simple or composite NS or to a
concatenation of such NS instances. From a resource management viewpoint, different NSIs can use instances of the
same type of NS (i.e. they are instantiated from the same NSD) with the same or different deployment flavours.
Alternatively, different NSIs can use instances of different types of NSs. The first approach can be used if the NSIs
share the same types of network functions (or a large common subset) but differ in terms of the performance expected
from these network functions (and from the virtual links connecting them) and/or the number of instances to be
deployed for each of them. If slices differ more significantly, mapping to different NSs, each with its own NSD can be
considered. The same mapping principles might apply to NSSIs.
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4.2.3.2.3 Network slice lifecycle management
3GPP TR 28.801 [i.21] describes the lifecycle of a network slice, which is comprised of the four following phases:
• Preparation;
• Instantiation, Configuration and Activation;
• Run-time;
• Decommissioning.
The preparation phase includes the creation and verification of NST(s). From an NFV perspective, the resource
requirement for a NST can be realized by one or more existing NSDs that have been previously on-boarded on the
NFVO. The creation of a new NST can lead to requiring update of an existing NSD or generation of a new NSD
followed by on-boarding the new NSD if the slice requirements do not map to an already on-boarded NSD
(i.e. available in the NSD catalogue). Indeed, the NS for the multiple NSIs may be instantiated with the same NSD, in
order to deliver exactly the same optimizations and features but dedicated to different enterprise customers. On the
other hand, a network slice intended to support totally new customer facing services is likely to require a new NS and
thus the generation of a new NSD.
The network slice instantiation step in the second phase triggers the instantiation of the underlying NSs. NFV-MANO
functions are only involved in the network slice configuration phase if the configuration of virtualisation-related
parameters is required on one or more of the constituent VNF instances. Configuration of the network applications
embedded in the constituent network functions involves the NSMF or NSSMF and/or other parts of the OSS/BSS, and
the element managers (if any) associated to these functions. NFV-MANO functions can be triggered during the network
slice activation step. If explicit activation of VNFs is required, the NSMF or the NSSMF can change the operational
state of those VNFs through an Update NS operation defined in ETSI GS NFV-IFA 013 [i.6].
The involvement of NFV-MANO in the run-time phase is limited to the operations related to the performance
management, fault management, and lifecycle management of virtualised resources (e.g. scaling an underlying NS to
expand a NSI).
The decommissioning phase triggers the termination of the underlying network service instances.
4.2.4 ONF
4.2.4.1 Network slicing abstraction and resource control from the ONF perspective
According to clause 3 of ONF TR-526 [i.17], slicing requires the partitioning and assignment of a set of resources that
can be used in an isolated, disjunctive or shared manner. A set of such dedicated resources can be called a slice
instance. Examples of resources to be partitioned or shared, understanding they can be physical or virtual, would be:
bandwidth on a network link, forwarding tables in a network element (switch, router), processing capacity of servers,
processing capacity of network elements. As it can be assumed that slice instances will often contain a
combination/group of the above resources, appropriate resource abstractions as well as the exposure of abstract
resources towards clients are needed for the operation of slices.
To comprehend the notion of a slice from the ONF perspective, it is important to understand the ONF SDN architecture
concept in general, especially the concepts of client context and server context which are defined in ONF TR-521 [i.16].
Major components of SDN are resources and controllers. Service delivery (send, receive, transmit, transform data)
makes use of resources. Provisioning, management and control of services and related resources are executed via the
controller.
The controller in the SDN architecture is at the centre of a feedback loop: it mediates client requirements with resource
availability, supporting policy-driven real-/run-time optimization of changes in network state, service parameters,
service and traffic flow.
An SDN controller works with two major types of resource views: it interacts with its client via a (client specific) client
context, and with its resources via a (server specific) server context.
The term virtualisation is used to describe the function of a controller to aggregate and abstract the underlying resources
it manages-controls. Views onto such virtualised resources, or resource groups dedicated to particular clients, are
provided to clients/applications/users via northbound interfaces.
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The term orchestration is used to describe the responsibility of the controller to dispatch resources in a way that
simultaneously satisfies service demands from all of its clients as cost-effectively as possible.

Figure 4.2.4.1-1: Core concepts of the SDN architecture and slice abstraction
(figure 2 in ONF TR-526 [i.17])
An SDN controller's client context provides the complete abstract set of resources and supporting control logic for
constituting a slice, including the complete collection of related client service attributes. The client context also offers to
the client functions to manage-control the slice resources, including OAM related-functions, as visible by/available to
the client according to administrative policy.
A client context represents the necessary and sufficient material in the SDN controller to support a given client, where a
client may be a customer, partner, or even another entity within the same administration that owns the controller. It
includes all of the attributes of a service as requested by the client, and may contain service-specific information
necessary to map service attributes into the realization of the service.
The resource group in a client context defines the semantic interfaces exposed to the client. Virtual resources represent
infrastructure resources that are created from the SDN controller's underlying resources through the process of
virtualisation, and that are exposed to the client by way of a mapping function. Support resources, which represent
functions hosted in the SDN controller itself, enable or facilitate interaction with the client. Examples for support
resources are: security credentials, notifications subscription, profiles, logs, etc.
NOTE: The administrator's client context is special in that it is used for the internal configuration and
management of (administrative) policies and constraints of the controller, including all client and server
contexts.
A server context is the symmetric counterpart to a client context. It contains everything necessary and sufficient to
interact with a group of underlying resources, which could be, for example, a discrete network element or the virtual
resources contracted from a partner domain.
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Resources fall into and may be combinations of the categories network, storage and compute, with resource capabilities
therefore ranging from simple, e.g. switching between ports, to complex, e.g. firewall with DPI or a video transcoder.
The state of the resources owned by the controller is continually adapted in compliance with policies provided by the
administrator. These policies include parameters to satisfy commitments to clients. For all ser
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