Internet Engineering Task Force                                H. Flinck
Internet-Draft                                                C. Sartori
Intended status: Informational                              A. Andrianov
Expires: January 4, 2018                                   C. Mannweiler
                                                             N. Sprecher
                                                            July 3, 2017

              Network Slicing Management and Orchestration


   Network Slicing is worked in multiple SDOs from different view
   points.  As network slicing is an end-to-end topic, this draft
   proposes that network slices architecture [NS-Framework] aligns with
   the work done in NGMN, 3GPP and ETSI with relation to management and
   orchestration.  The key aspect that this draft makes is the rational
   for role and need for Network Slice Management Function (NSMF) entity
   that operates above Network Virtualization Function Orchestrator and
   PNFs Management Functions.  NSMF needs to support different
   abstractions of resources and to offer access to different management

Status of This Memo

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   Copyright (c) 2017 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Acronyms and Abbreviations  . . . . . . . . . . . . . . .   5
   2.  Different levels of Network Slice Control exposure  . . . . .   5
   3.  Network Slice Management Function (NSMF)  . . . . . . . . . .   6
   4.  IANA considerations . . . . . . . . . . . . . . . . . . . . .   8
   5.  Security considerations . . . . . . . . . . . . . . . . . . .   8
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   8
   7.  Informative References  . . . . . . . . . . . . . . . . . . .   8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   9

1.  Introduction

   The purpose of this draft is to highlight the essential aspects of
   network slice management from 3GPP, NGMN and ETSI relevant for the
   network slices architecture as described in [NS-Framework] and to
   propose a minimal alignment between these works to ensure
   compatibility between them.  NGMN documents
   "161010_NGMN_Network_Slicing_framework_v1.0.8" [NGMN_NS] and "5G
   Network and Service Management including Orchestration" [NGMN_NSMN]
   define Network Slicing and how it relates to overall Service and
   Network Management architecture.  The NGMN documents define as well
   the terminology adopted later by 3GPP and reflected in 3GPP
   [TR28.801].  In this paper, for sake of simplicity, only an
   "executive summary" of network slicing is given, while relying on
   both terminology and complete descriptions on the above mentioned

   Network Slicing provides multiple logical networks on top of a
   partially shared network infrastructure as described in
   [NS-Framework].  Each instance of a network slice represents an
   independent end-to-end network that allows deployment of different
   architectural flavors in parallel slices.  These slices may be
   deployed and/or operated by the slice provider, or by the tenant who
   requested the slice.

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   A network slice can span across different administrative domains.
   NGMN Network slicing white paper [NS-Framework] defines various
   forward-looking business models engaging multiple administrative
   domains that may be envisioned in the industry.  An administrative
   domain refers to the scope of jurisdiction of a provider.  A provider
   may obtain services from 3rd parties (i.e. sub-providers) to enrich
   the services it provides to its end customers.  A provider could also
   benefit from offering its spare capabilities or resources to other
   providers becoming itself a sub-provider.  A network service can be a
   single user connectivity service, NaaS (Network as a Service) such as
   a service instance, a network slice instance or a subnetwork slice
   (note NGMN and 3GPP use a different terminology for what IETF
   netslices drafts call for "network slice segment") instance offering
   for a business vertical that utilizes forward-looking business
   models, or IaaS (Infra structure as a Service).

   Depending on the use cases and type of services for which the end-to-
   end slice has been instantiated multiple levels of control may be
   exposed to the tenants by the slice provider.  On the lowest level of
   the exposed control the network slice provider grants only access to
   use the slice and means to monitor its performance.  At second level
   a control exposure is to allow tenants to change the configuration of
   the network functions associated to the tenant's network slice.  At
   the highest level of control tenants can compose network slices and
   manage them with their own management system.  These different levels
   of control exposure require that the network slice management must
   work on multiple levels of abstractions where highest level is at the
   Service Management & Orchestration (M&O) and lowest level at the
   network functions.  The slice provider must be able to isolate these
   control functions of different tenants to match the "Slice Provider"
   - "Slice Consumer" -relationship.

   A network slice instance can contain virtualized network functions as
   well as physical network functions.  Virtualized network functions
   (VNF) are decoupled from physical network equipment by a
   virtualization layer.  Both the lifecycle of the types of the network
   functions can span beyond the lifecycle of a Network Slice and they
   need their own life cycle management functions.  The life cycle
   management of these two types of network functions differ.  The
   environment in which VNFs are deployed is called Network Functions
   Virtualisation Infrastructure (NFVI) and is managed by Virtualised
   Infrastructure Manager (VIM) according to ETSI NFV-MANO [MANO]
   reference architecture.  VNFs are instantiated by requests of NFV
   Orchestrator (NFVO).  In the MANO architecture NFV Orchestrator
   (NFVO) uses VNF Managers for the lifecycle management of VNF
   instances and the VIM allocates the needed virtualized resources as
   requested by the NFVO into the NFVI.  However, the same approach
   cannot be applied to network functions of dedicated hardware

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   (Physical Network Functions, PNF) as their resources are not
   controlled by NFVO nor VIMs.  Network Functions (whether PNF or VNF)
   require their function specific management, as well as their resource

   When adding support for the virtualized version of the PNFs their
   management systems will evolve to either extend their capability with
   an embedded VNF management functionality or will delegate their
   virtual resource management to an external VNF manager.  In either
   case, the VNF management function interacts with the NFVO and the VIM
   through the MANO defined interfaces and provides the cloud resource
   FCAPS management for the network functions.  Another key issue for
   provisioning of network slices is the identification, design, and
   management of network functions which can be shared by multiple end-
   to-end slices [Rost].

   For Network slice management function (NSMF), which is a slice-
   dedicated function with slice-specific view on any FCAPS data and
   management procedures, such sharing or common usage should be
   transparent, i.e., the multiplexing of multiple network slices to a
   commonly used function/element is done by EMS/NMS.  NSMF operates
   above NFVO and PNFs Management Functions in the Service M&O.  In view
   of 3GPP as well as ETSI NFV, NSMF belongs to OSS/BSS.  When a network
   slice contains PNFs the NSMF instructs the PNFs Management Functions
   to configure the physical network components to deliver the required
   slice characteristics.

   This draft introduces the role of NSMF in the context of 3GPP
   [TR28.801], [TS28.530] and ETSI [MANO] work and reflects that back to
   netslices-architecture presented in [NS-Framework].  We argue that
   the NSMF is at the Service M&O level, even at a tenant.  This is
   because of several reasons:

   o  Need for exposing different levels of network slice control to the

   o  Different life cycle management approaches for PNFs and VNFs.
      NSMF must have interfaces both to NFVO and to PNFs Management and
      is therefore above of the NFVO and PNF management and it should
      support service level abstractions.

   Network slicing is end-to-end concept, thus including several network
   components, (Network Slice Subnetwork Functions according to 3GPP
   terminology).  Often those components belong to different
   administrative domains (e.g.  RAN, Core Network, Transport) and
   therefore the need for a higher level of abstraction.  Transport
   network [ACTN] is a subnetwork slice in the 3GPP model and recursion
   can be applied to slices as well as to subnetwork slices.

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1.1.  Acronyms and Abbreviations

   This document uses the following acronyms:

   3GPP    3rd Generation Partnership Project
   BSS/OSS Business Support Systems/Operations Support Systems
   EMS     Element Management System
   ETSI    European Telecommunications Standards Institute
   FCAPS   Fault, Configuration, Accounting, Performance, Security
   IaaS    Infra structure as a Service
   KPI     Key Performance Indicator
   MANO    ETSI Management and Orchestration
   LCM     Life Cycle Management
   MNO     Mobile Network Operator
   M&O     Management & Orchestration
   NaaS    Network as a Service
   NGMN    Next Generation Mobile Networks
   NMS     Network Management System
   NSMF    Network Slice Subnet Management Functions
   NSSMF   Network Slice Management Function
   NFVI    Network Functions Virtualisation Infrastructure
   NVFO    Network Virtualization Function Orchestrator
   PNF     Physical Network Function
   RAN     Radio Access Network
   SLA     Service Level Agreement
   VIM     Virtualised Infrastructure Manager
   VNF     Virtualised Network Function

2.  Different levels of Network Slice Control exposure

   Depending on the "Slice Provider" - "Slice Consumer" -relationship
   the Slice Provider can offer various levels of control to the Slice
   Consumers.  Roughly speaking levels of control can be categorized
   onto follow cases:

   1.  Monitoring only.  The Slice Provider offers only means to monitor
       the slice KPIs as agreed in the contract.  Network slice
       configuration is chosen from a catalogue of readymade slice
       templates.  Accesses via dashboard-like web service and/or north
       bound interfaces provided by the Slice Provider.

   2.  Limited control to Slice Consumer to perform design and
       composition of network slice.  Slice Consumer can change
       configuration of deployed network functions and /or onboard own
       certified network functions into Slice Provider's repository
       using interfaces provided by the Slice Provider.

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   3.  Extended Control.  In this case the Slice Consumer deploys and
       operates the network slice using its own MANO stack and NMS.  The
       Slice consumer has tight control over its own network functions
       and services while has limited control over MNO network

   Because of these varying levels of network slice control, the NSMF
   needs to support different abstractions of resources and to offer
   access to different management entities (e.g.  PNFs management
   functions, NFV-MANO).  Consequently, the logical place for NSMF
   function in the network slice management architecture is at the
   Service Management & Orchestration (M&O).

3.  Network Slice Management Function (NSMF)

   Network slicing concept of NGMN consists of 3 layers: Service
   Instance Layer, Network Slice Instance Layer, and Resource layer
   [NGMN_NS].  The Service Instance Layer is managed by service
   orchestrator that is considered to be part of BSS/OSS according to
   the 3GPP view [TR28.801].  Network Slicing Instance Layer is a
   Business to Business service and may pass across multiple
   administrative domains.  Network Slice Management Function resides at
   this layer and is consequently part of Service Orchestration and BSS/

   The end-to-end network slice management (NSMF) can use different
   technology domains and their segments to create an end-to-end slice.
   It has full visibility and control to the end-to-end slice and its
   performance.  It resides above the Network Slice Subnet Management
   Functions (NSSMF).  It monitors slice specific FCAPS to maintain and
   to expose the overall SLAs of the end-to-end slices to the tenant.

   NSMF interfaces domain specific Network Management and Element
   Management Systems through Network Slice Subnet Management Functions
   (NSSMF).  In addition, NSMF also interfaces NFV-MANO to manage
   virtualization aspects (through "OS-Ma-nfvo"-interface).

   NSSMF manages Network Slice Subnet (3GPP defined management
   abstraction) composed of Network Functions (virtualized or not) and
   other Network Slice Subnets (recursion principle).  NM/EM could play
   the role of NSSMF.  For management of virtualization aspects (such as
   NS and VNF LCM) and TN, NSSMF interacts with NFV-MANO (through "Os-
   Ma-nfvo"-interface).  The 3GPP defined Network Slice Subnets
   correspond to ETSI NFV defined NSs composed from either network
   functions and/or nested network slices (recursion principle).

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   | BSS/OSS                            |
   |        +-----------------------+   |
   |        | Service M&O           |   |
   |        |                       |   |
   |        |  +-------------+      |   |
   |        |  |    NSMF     +--------------------------+
   |        |  ++------------+      |   |               |
   |        +---|-------------------+   |               |
   +------------|-----------------------+               |
                |                                       |
                |                                       |
     +----------|-----+                                 |
     | NM/EM    |     |                                 |
     |   +------+-----+                           +-----+------+
     |   |            |                           |            |
     |   |            |                           |    NFV     |
     |   |    NSSMF   +---------------------------+    MANO    |
     |   |            |                           |            |
     |   |            +------------+              |            |
     +---+------+-----+            |              +-----+------+
                |                  |                    |
                |                  |                    |
          +-----+-----+            |               +----+------+
          |           |            |               |           |
          |   PNFs    |            +---------------+   VNFs    |
          |           |                            |           |
          +-----+-----+                            +----+------+
                |                                       |
                |                                       |
                |                                       |
      |       Slice with shared and dedicated network functions       |

             Network Slice Management functional architecture.

                                 Figure 1

   Based on the above reasoning we propose to replace the "Figure 2: E2E
   Slice Orchestration"-figure of the section of Management and
   Orchestration of Network Slicing in [NS-Framework] with the following
   figure with the above stated reasoning.

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               + ------------------------------------------------+
               |                  NSMF                           |
                  |              |                           |
        +-----------+      +-----------+                 +----------+
        | Network   |      | Network   |                 | Network  |
        | Slice     |      | Slice     |                 | Slice    |
        | Subnet    |      | Subnet    |                 | Subnet   |
        | Management|      | Management|                 |Management|
        | Function  |------| Function  |------  ...  --  |Function  |
         +----------+      +-----------+                 +----------+
              |                    |                          |
        |   P/VNF FCAPS Management  /  NFV-MANO: VNF LCM management  |
             |            |                  |                 |
        +--------+   :  +--------+   :  +--------+   :       +--------+
        | PNF 1  |----- | PNF n   |----- | VNF 1 |----...--  | VNF n  |
        +--------+   :  +--------+   :  +--------+   :       +--------+

       Network Slice Management Function (Network Slice segment term
    corresponds roughly to Network Slice subnetwork term used by 3GPP/

                                 Figure 2

4.  IANA considerations

   This document makes no request of IANA.

5.  Security considerations

   Each element and their interface of the proposed management
   architecture needs to address their security requirements.

6.  Acknowledgements

7.  Informative References

   [ACTN]     Ceccarelli, D. and Lee, Y., "Framework for Abstraction and
              Control of Traffic Engineered Networks", draft-ietf-teas-
              actn-framework-06 (work in progress), June 2017.

   [MANO]     ETSI, "ETSI GS NFV-MAN 001: Network Functions
              Virtualization (NFV); Management and Orchestration", 2014.

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   [NGMN_NS]  NGMN Alliance, "Description of Network Slicing Concept",
              media/161010_NGMN_Network_Slicing_framework_v1.0.8.pdf  ,

              NGMN Alliance, "5G Network and Service Management
              including Orchestration",
              orchestration.html  , 2017.

              Geng, L., Dong, J., Bryant, S., Makhijani, K., Galis, A.,
              De Foy, X., and Kuklinsk, S., "Network Slicing
              Architecture", draft-geng-netslices-architecture-01 (work
              in progress), June 2017.

   [Rost]     Rost, P., Mannweiler, C., Diomidis, M., Sartori, C.,
              Sciancalepore, V., Sastry, N., Holland, O., Tayade, S.,
              Han, B, Bega, D., Aziz, D., Bakker, H., and IEEE
              Communications Magazine, Volume: 55 Issue: 5,, "Network
              Slicing to Enable Scalability and Flexibility in 5G Mobile
              Networks", May 2017.

              3GPP, "Study on management and orchestration of network
              slicing for next generation network, Release 14)3GPP TR
              28.801 V1.2.0",
              SpecificationDetails.aspx?specificationId=3091  , 2017.

              3GPP, "Management of network slicing in mobile networks;
              Concepts, use cases and requirements. Technical
              specification. Release 15. 3GPP TR 28.530.",
              SpecificationDetails.aspx?specificationId=3091  , 2017.

Authors' Addresses

   Hannu Flinck

   Phone: +358504839522

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   Cinzia Sartori

   Phone: +491713008990

   Anatoly Andriannov
   Arlington Heights, IL

   Phone: +1-847-668-0394

   Christian Mannweiler

   Phone: +491715581581

   Nurit Sprecher
   Hod HaSharon

   Phone: +97297751229

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