Network Working Group                                            L. Geng
Internet-Draft                                              China Mobile
Intended status: Informational                              S. Kuklinski
Expires: March 29, 2018                                           Orange
                                                                L. Qiang
                                                     Huawei Technologies
                                                           S. Matsushima
                                                                A. Galis
                                               University College London
                                                         Luis. Contreras
                                                      September 25, 2017

     Problem Statement of Supervised Heterogeneous Network Slicing


   This document discusses the general requirements and problem
   statement of supervised heterogeneous network slicing.  The purpose
   of this document is to identify the key network components that are
   used to create a network slice instance.  Base on this information, a
   general network slice template can be visualized.  Furthermore, the
   requirement of a common information model is identified and
   corresponding management consideration of heterogeneous network slice
   instance is also discussed.

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   This Internet-Draft will expire on March 29, 2018.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
     1.2.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  The components for a network slice instance . . . . . . . . .   4
     2.1.  Connectivity of network slice instance  . . . . . . . . .   5
     2.2.  Computing for network slice instance  . . . . . . . . . .   5
     2.3.  Storage for network slice instance  . . . . . . . . . . .   6
     2.4.  Pre-defined function block for network slice instance . .   6
   3.  The requirements of common information model for supervised
       heterogeneous network slice . . . . . . . . . . . . . . . . .   7
     3.1.  Management of heterogeneous network slice . . . . . . . .   8
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   9
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   9
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   9
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   9
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   9
     7.2.  Informative References  . . . . . . . . . . . . . . . . .   9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  10

1.  Introduction

   The concept of network slicing is not new but energized greatly under
   5G work in 3GPP.  It is expected that further 5G network should be
   capable of providing dedicated private network for different
   verticals according to their specific requirements, which are created
   by diversity of new services such as high definition (HD) video,
   virtual reality (VR) and V2X applications.  Looking at the
   development of future network, no matter the service is connected via
   5G cellular RAN, FTTx optical access network or other dedicated
   connections, this resource dedication has become a fundamental
   technology for services requiring extreme quality of user experience.

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   The best effort transport is not good enough as both subscribers and
   application providers are looking for and willing to pay for certain
   level of quality dedication.  Therefore it is inevitable for service
   providers (telecommunication infrastructure owners) to rethink the
   means of management and operation of their networks, which should
   support end-to-end slicing capabilities.

   The requirements from different verticals may be extremely
   diversified.  Typical examples includes high bandwidth, low latency,
   high level of isolation, specific security and encryption
   requirements and etc.  These requirements may also change dynamically
   along time since the services of certain industry vertical changes
   very fast, and sometime spontaneously (i.e. burst bandwidth/latency
   requirement from on-line shopping provider on certain period).  It is
   expected that the configuration of certain network slice instances
   are very dynamic in a case-by-case manner.  Meanwhile, there are many
   technology options to fulfil particular requirements depending on
   considerations on many aspects including cost, TTM and etc.  The
   diversity of both requirements and technology options makes network
   slices significantly heterogeneous.

   In order to provide cost-effective and efficient network slice
   configuration, service provider needs to understand specifically the
   components it can make use to create a network slice instance and how
   these components map with the customer requirements.  These
   components include both network resources and management entities.

1.1.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in RFC 2119.

1.2.  Terminology

   Network Slice Instance - A network slice instance (NSI) is a managed
   group of subsets of network resources, network functions and network
   management entities, forming a complete instantiated logical/physical
   network to meet certain network characteristics required by the
   network slice tenant(s).  A network slice instance may also be shared
   across multiple services provided by the network slice tenant.  It is
   re-configurable and is managed by network slice provider.

   Network Slice Provider - A network slicing provider (NSP), typically
   a telecommunication service provider, is the owner or tenant of the
   network infrastructures from which network slices are created.  The
   network slicing provider takes the responsibilities of managing and

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   orchestrating corresponding resource and management components that
   the network slicing consists of.

   Network Slice End-point - A network slice end-point (NSE) is a
   network-slice-aware terminal, typically subscribed to the service
   which is hosted in a network slice instance.  A network slice end-
   point may be capable of subscribing to multiple services hosted
   independently in different network slice instance simultaneously.

   Network Slice Tenant - A network slice tenant (NST) is the user of
   specific NSIs, in which specific services are hosted and can be
   provided to NSEs.  Network slice tenants can make requests of the
   creation of new network slice instances.  Certain level of management
   capability should be exposed to network slice tenant from network
   slice service provider by pre-allocated outsource management

   End-to-end Network Slice - A cross-domain network slice which may
   consist of access network (fixed or cellular), transport network,
   (mobile) core network and etc.  End-to-end network slice can be
   customized according to the requirements of network slice tenants

   Network Function (NF) - A processing function in a network.  It
   includes but is not limited to network nodes functionality, e.g.
   session management, mobility management, switching, routing
   functions, which has defined functional behaviour and interfaces.
   Network functions can be implemented as a network node on a dedicated
   hardware or as a virtualized software functions.  Data, Control,
   Management, Orchestration planes functions are Network Functions.

   Virtual Network Function (VNF) - A network function whose functional
   software is decoupled from hardware.  One or more virtual machines
   running different software and processes on top of industry-standard
   high-volume servers, switches and storage, or cloud computing
   infrastructure, and capable of implementing network functions
   traditionally implemented via custom hardware appliances and middle-
   boxes (e.g. router, NAT, firewall, load balancer, etc.)

2.  The components for a network slice instance

   Fundamentally, NSIs are created based on the shared network
   infrastructures.  One can not create or define an NSI with components
   that are not available in the shared infrastructure.  Hence, it is
   extremely important, both for NST and NSP, to understand a clear
   scope of the usable components for NSI construction.  An NSP can
   therefore refer to this general scope to decide how each component
   can be orchestrated and provided as a packaged network slice service
   to NSTs.  Based on this information, NSP can also further outline and

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   figure out the what capability each component can offer and how they
   meet NST's demands.  Overall, it is not possible to map the offered
   capability of a network slice instance with the specific demands from
   an NST if an NSP is not clear on what components and corresponding
   characteristics can be provided.

   Network slice instance consists of dedicated network resources which
   are orchestrated using all the available components offered by a NSP
   network.  In general, the components that an NSP can use to create an
   NSI include connectivity, computing, storage, and management entity.

2.1.  Connectivity of network slice instance

   Connectivity is one of the essential components for an NSI.  It can
   be as simple as a best effort point-to-point VPN or a dedicated
   complex topology with other specific requirements including
   bandwidth, latency and etc.  The characteristics of the connectivity
   component should include the following aspects.

   o  Connection topology - The description of connection topology of a
      NSI.  It should explicitly describe the connectivity relationship
      between each access point of the NSI.  An NSP should be able to
      understand the overall connectivity requirement of an NSI from
      this topology information.

   o  Bandwidth - The description of bandwidth requirements of specific
      links within an NSI.  The requirements includes exactly amounts of
      assured bandwidth, maximum bandwidth and other bandwidth QoS-
      specific requirements

   o  Latency - The description of link latency requirements within an
      NSI.  It should identify the exact amount of latency between a
      link defined in connection topology.

   o  Determinism - The description of the determinism of a link
      latency.  This should be defined in addition to the latency, which
      further specify the jitter of the latency for a given link.

   o  Isolation level - The description of isolation level of an NSI.  A
      NST may request logical isolation which can be mapped to
      tunnelling technologies.  It may also request explicitly a
      dedicated lamda or even physical link for specific services.

2.2.  Computing for network slice instance

   If an NST would like to host virtualized functions in an NSI, it may
   be interested in asking for specific computing resource including

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   both bare metal common servers and virtual machines.  This resource
   should also be specified considering the following characteristics.

   o  CPU resources - The physical and virtual CPU specifications a NST
      may request a NSP to provide.

   o  GPU resources - The GPU specifications a NST may request a NSP to

   o  RAM resources - The RAM size associated with the requested
      computing resources in a NSI.

   Instead of providing bare metal resources, NSP may also provide
   ready-to-used virtual machines and containers as part of the NSI.
   This virtual resources need also be specified with virtulization
   technology options, CPU/Virtual CPU requirements and etc.

2.3.  Storage for network slice instance

   It is necessary for NSP to provide storage components in an NSI since
   NSTs may want to host contents on dedicated resources.  Meanwhile,
   NSP may also prefer to use dedicated storage for specific service
   policies,authentication information and other management profiles.

   o  General storage - The description of storage resource in a NSI.
      This may include the location, type, size and usage of the storage
      resource.  The general storage requirements may closely related to
      the connectivity topology as well.

   o  CDN service - If an NSP can provide a turn-key CDN solution for
      the NST.  It can also include CDN service withing an NSI

2.4.  Pre-defined function block for network slice instance

   Many dedicated network functions, either physical or virtual, may
   requested by a NST.  Typical example include common network functions
   as DHCP server, DNS, NAT, Firewall, SDN controller.  Application-
   level functions may also exist in a NSI, such as session management,
   mobility management and etc.  NSP should be able to provide such pre-
   defined function blocks according to NST's request.

   o  Physical network function blocks- The description of dedicated
      physical network functions.  Physical network functions are
      network equipments with dedicated software and hardware, which are
      strictly coupled for the purpose of a providing specific network

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   o  Virtual network function blocks- The description of virtualized
      network functions.  VNFs are software entities which are normally
      hosted within pre-allocated virtual machines (or containers).  The
      virtual resources which are required by the VNF should be also
      specified in terms of computing resources as described previously.

3.  The requirements of common information model for supervised
    heterogeneous network slice

   As NSTs are not expected to be "network experts", the requirements
   injected to a NSP may be diversified in forms.  NSP may have
   different preferences for the network slice service model provided to
   potential NSTs.  However, there is a need for a common information
   model which explicitly describes the components and parameters within
   a NSI.

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                              Slice Tenant
                   |        Slice Provider            |
                   |        Slice Manager             |
                   |    +------------------------+    |
                   |    |Common Information Model|    |
                   |    +------------------------+    |
                         |         |
            |            |                                   |
            | +----------|---------------------------+       |
            | | +--------v-------+ +--------------+  |       |
            | | |  Mngt Agent    | |IntraNS Mngt  |  +----+  |
            | | +----------------+ +--------------+  |    |  |
            | | +---------------------------------+  |    |  |
            | | | Connectivity, Computing         |  |    |  |
            | | | Storage, Pre-defined Functions  |  |    |  |
            | | |                                 |  |    |  |
            | | +---------------------------------+  |    |  |
            | |                                  NSI |    |  |
            | +----+---------------------------------+    |  |
            |      |                                  NSI |  |
            |      +--------------------------------------+  |
            |             Network Infrastructure             |

             Figure 1: Supervised heterogeneous network slice

   As seen in Figure 1.  The common information model is used to
   describe a NSI according to the service model provided by NSTs.  It
   is then further de-composited to models that are used by various
   management domain within the NSP's network infrastructure.

3.1.  Management of heterogeneous network slice

   The network slice management include two levels.  One is network-
   slice level management which is maintained by NSP, the other is
   intra-slice management which is maintained by NST but supervised by

   o  Network slice management agent - This is the NS-level management
      agent provided by NSP.  Each created NSI should have a logical

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      entity serving as a network slice management agent.  It executes
      the OAM messages received from the NSP network slice manager
      including life-cycle management, monitoring and etc.  A profile of
      the created NSI should also be maintained within this agent, where
      the status of each element can be managed.

   o  Intra-slice management - As per agreement between NST and NSP,
      intra-slice management may be provide by NSP to oversee an given
      NSI as a general private network.  NST are authorized to use this
      management capability to maintain the NSI.  The NSI-level
      information is transparent to intra-slice management, which means
      the management system does not know the existence of network slice
      instances.  The exposed management capability should be supervised
      by the NSP, so that the NSI will not violate NSI-level policies.
      Meanwhile, intra-slice management


4.  IANA Considerations

   This document makes no request of IANA.

5.  Security Considerations

   Each layer of the system has its own security requirements.

6.  Acknowledgements

7.  References

7.1.  Normative References

              Finn, N. and P. Thubert, "Deterministic Networking
              Architecture", draft-finn-detnet-architecture-08 (work in
              progress), August 2016.

              Qin, J.,, k., Dong, J., Qiang,
              L., and S. Peng, "Network Slicing Use Cases: Network
              Customization for Different Services", draft-qin-
              netslices-use-cases-00 (work in progress), March 2017.

7.2.  Informative References

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   [NS_WP]    China Mobile Communication Corporation, Huawei
              Technologies Co. Deutsche Telekom AG,Volkswagen, "5G
              Service-Guaranteed Network Slicing White Paper", 2016,

Authors' Addresses

   Liang Geng
   China Mobile


   Slawomir Kuklinski


   Li Qiang
   Huawei Technologies
   Huawei Campus, No. 156 Beiqing Rd.
   Beijing  100095


   Satoru Matsushima


   Alex Galis
   University College London


   Luis Miguel Contreras Murillo


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