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Versions: 00 01 02                                                      
Network Working Group                                          X. de Foy
Internet-Draft                                                 A. Rahman
Intended status: Informational          InterDigital Communications, LLC
Expires: September 7, 2017                                 March 6, 2017


                    Network Slicing - 3GPP Use Case
             draft-defoy-netslices-3gpp-network-slicing-00

Abstract

   This document describes work conducted at the 3GPP standard
   organization on 5G Network Slicing.  Its goal is to provide a
   detailed use case, and help better define requirements, for Internet
   Protocols supporting Network Slicing.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
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   Internet-Drafts are draft documents valid for a maximum of six months
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   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on September 7, 2017.

Copyright Notice

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

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
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   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.




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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Background  . . . . . . . . . . . . . . . . . . . . . . .   3
     1.2.  NS Work in 3GPP Prior to 5G Phase 1 . . . . . . . . . . .   3
   2.  Network Slicing Requirements in 3GPP  . . . . . . . . . . . .   3
   3.  Network Slicing in Logical 5G Architecture in 3GPP  . . . . .   4
     3.1.  Early Work on RAN Slicing . . . . . . . . . . . . . . . .   7
   4.  Management Aspect of Network Slicing in 3GPP  . . . . . . . .   8
   5.  5G Virtual Infrastructure Management in 3GPP  . . . . . . . .   8
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  10
   7.  Conclusion  . . . . . . . . . . . . . . . . . . . . . . . . .  12
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  13
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  13
   10. Informative References  . . . . . . . . . . . . . . . . . . .  13
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  15

1.  Introduction

   This document describes work conducted at the 3GPP standard
   organization on 5G Network Slicing.  Its goal is to provide a
   detailed use case, and help better define requirements, for Internet
   Protocols supporting Network Slicing.

   The concept of Network Slicing (NS) is considered a key mechanism for
   5G networks to serve vertical industries with widely different
   service needs, in term of latency, reliability, capacity, and domain
   specific extra functionalities.  It does so by exposing isolated
   partitions of network resources and services.  The IETF Bar-BoF
   NETSLICES activity studies the need for supporting protocols.  In
   particular, [I-D.gdmb-netslices-intro-and-ps] defines Network Slicing
   in a broad context and suggests related problems and work areas.  It
   also identifies the need to provide use cases such as, for example,
   ultra-low latency and massive-connectivity machine communication
   services.  We propose to review ongoing NS work in 3GPP within the
   present document.  This constitutes in our view another valid type of
   use case, since 3GPP architecture may ultimately use or integrate
   with NS solutions defined in IETF.

   Sections 2 to 6 aim to represent the current state of network slicing
   and related aspects in 3GPP.  We attempted to leave our own analysis
   out of these sections and present it into section 7.  For simplicity,
   3GPP-specific acronyms are defined in the section they are used,
   which is mostly section 3.







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1.1.  Background

   The 3GPP standard organization is in the process of developing 5G
   system architecture, which includes network slicing.  In the present
   document we will use information collected from 3GPP Release 15
   specifications (as well as preliminary studies from Release 14 when
   specifications are not yet available).  This release aims to address
   a more urgent subset of commercial needs in "5G Phase 1", with
   expected deployments in 2020.  Work on network slicing is split
   between different working and study groups, reviewed here in separate
   sections.

1.2.  NS Work in 3GPP Prior to 5G Phase 1

   While the present document will only focus on Network Slicing in 5G
   Phase 1, an early form of network slicing was introduced in Release
   13, with the Dedicated Core Network (DCN) or DECOR feature, where
   dedicated core network nodes are forming a DCN serving subscribers or
   devices with a certain "usage type" (e.g. machine-to-machine or
   enterprise).  In the Release 14 eDECOR feature, the DCN selection
   mechanism was extended to be assisted by the device, which can now
   send its usage type to the RAN.  This is specified in [_3GPP.23.401].
   Deployments are expected in 2017 and 2018.

2.  Network Slicing Requirements in 3GPP

   Network slicing requirements are included in [_3GPP.22.261].  There
   are requirements related to:

   o  Provisioning: create/modify/delete network slices, provision
      network functions to be used in slices, define network services
      and capabilities supported by a network slice.

   o  Managing association to slices: configure association of devices
      and services to network slices, move/remove user between/from
      slices.

   o  Interoperating: support roaming and non-roaming using the same
      home slice, support devices simultaneously connected to multiple
      slices.

   o  Supporting performance and isolation: support dynamic slice
      elasticity, ensure performance isolation during normal and elastic
      slice operation and during slice creation or deletion, enable
      operators to differentiate performance and functionalities between
      slices.





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3.  Network Slicing in Logical 5G Architecture in 3GPP

   5G network architecture is entering its normative stage in 2017 with
   a "5G System - Phase 1" Release 15 work item, which is in the process
   of producing two technical specifications: 23.501 "System
   Architecture for the 5G System" and 23.502 "Procedures for the 5G
   System".  At this early stage, though, we will still need to refer to
   the earlier technical report [_3GPP.23.799].  The following text
   summarizes what has been agreed about network slicing (refer to
   section 8.1 of that report for more details).

   A network slice is a complete logical network including Radio Access
   Network (RAN) and Core Network (CN).  It provides telecommunication
   services and network capabilities, which may vary (or not) from slice
   to slice.  Distinct RAN and core network slices will exist.  A device
   may access multiple slices simultaneously through a single RAN.

   The device may provide Network Slice Selection Assistance Information
   (NSSAI) parameters to the network to help it select a RAN and a core
   network part of a slice instance for the device.  A single NSSAI may
   lead to the selection of several slices.  The network may also use
   device capabilities, subscription information and local operator
   policies to do the selection.

   A NSSAI is a collection of smaller components, Session Management
   NSSAIs (SM-NSSAI), which each include a Slice Service Type (SST) and
   possibly a Slice Differentiator (SD).  Slice service type refers to
   an expected network behavior in terms of features and services (e.g.
   specialized for broadband or massive IoT), while the slice
   differentiator can help selecting among several network slice
   instances of the same type, e.g. to isolate traffic related to
   different services into different slices.

   A PDU session is a 5G concept for an association between the device
   and a data network, which can be IP, Ethernet or Unstructured (i.e.
   transparent to the 5G system).  The device will associate an
   application with one out of multiple parallel PDU sessions, each PDU
   session correspond to one core network slice and one RAN slice.
   Different PDU sessions may belong to different slices.  More
   precisely, an application will be associated with a SM-NSSAI (as
   mentioned above, this includes a slice service type and may also
   include a service differentiator), and data for this application will
   be routed to a PDU session associated to this SM-NSSAI.

   Part of the control plane, the Common Control Network Function
   (CCNF), is common to all or several slices.  It includes the Access
   and mobility Management Function (AMF) as well as the Network Slice
   Selection Function (NSSF), which is in charge of selecting core



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   network slice instances.  Besides those shared functions, different
   slices may also have dedicated control plane functions such as the
   Session Management Function (SMF), which manages PDU sessions.  User
   plane functions are dedicated to each slice.  The RAN selects a CCNF
   for a new PDU session.  CCNF may initiate the redirection of service
   for a device towards another CCNF, initially at session setup, or
   later on.

   In figures 1 and 2 we attempt to represent the use of network slicing
   in 3GPP logical architecture (those figures are our interpretation
   and are not directly adapted from the report).  Figure 1 represents
   the role of NSSAI in network selection.  Figure 2 represents the
   major network functions and interfaces in the context of RAN and Core
   Network slicing.  The terms used in these diagrams were introduced
   earlier.  System description and diagrams in section 4 of
   [_3GPP.23.501] can provide additional context.



































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                                  +-------+
                                  |       |
                                  |Device |
                                  |       |
                  RAN uses NSSAI  +---+---+
                  to select CCNF      |
                                \     |(NSSAI)
                                 \    |
                                  +---+---+
                                  |       +-------------+
                CCNF uses NSSAI   |  RAN  +---------+   |
                to select slice   |       |         |   |
                or redirect to    +---+---+         |   |
                another CCNF          |             |   |
                            \         |(NSSAI)      |   |
                             \        |             |   |
                              +-------+--------+    |   |
                              | Common Control |    |   |
                              | Plane Network  |    |   |
                              |    Functions   |    |   |
                              |    (CCNF)      |    |   |
                              +-----+----+-----+    |   |
                                    |    |          |   |
                                    |    |          |   |
                                    |    |          |   |
                          +---------|----+----------|---+-------+
                          |         |               |           |
                       +------------|---------------|-------+   |
                       |  +---------++        +-----+----+  |   |
                       |  |          |        |          |  |   |
                       |  | +------+ |        | +------+ |  |   |
                       |  | |      | |        | |      | |  |   |
                       |  | |CP NF1| |        | |UP NF1| |  |   |
                       |  | |      | |        | |      | |  |   |
                       |  | +------+ |        | +------+ |  |   |
                       |  |    ...   |        |    ...   |  |   |
                       |  |          |        |          |  |   |
                       |  | +------+ |        | +------+ |  |   |
                       |  | |      | |        | |      | |  |   |
                       |  | |CP NFn| |        | |UP NFn| |  |   |
                       |  | |      | |        | |      | |  |   |
                       |  | +------+ |        | +------+ |  |   |
                       |  |          |        |          |  +---+
                       |  +----------+        +----------+  |
                       +------------------------------------+
                            Core Network Slice Instances

          Figure 1: Network Slice Selection in 3GPP architecture



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                    CCNF         Network Slice Instance
            +-----------------+---------------------+
            |                 |                     |
            |                 |                     |
            |   +--------+    |     +--------+      |
            |   | Control|    |     | Control|      |
       +--------+ Plane  +----------+ Plane  |      |
       |    |   | AMF... |    |     | SMF... |      |
       |    |   +--------+    |     +----+---+      |
       |    |                 |          |          |
       |    |                 |          |          |
       |    |                 |          |          |
   +---+--+ +-----------------+          |          |
   |Device| |                 |          |          |
   +---+--+ |                 |          |          |
       |    |                 |          |          |
       |    |   +--------+    |   +------+-----+    |
       |    |   |        |    |   | User Plane |    | +---------------+
       +--------+  RAN   +--------+ Functions  +------+Data Network or|
            |   |        |    |   |            |    | | The Internet  |
            |   +--------+    |   +------------+    | +---------------+
            |                 |                     |
            |                 |                     |
            +-----------------+---------------------+
                 RAN Slice

               Figure 2: Network Slices in 3GPP architecture

3.1.  Early Work on RAN Slicing

   In line with the logical architecture described above, early work on
   RAN slicing is being conducted as part of the larger Release 14
   "Study on New Radio Access Technology".  Key principles are likely to
   include the following, extracted from [_3GPP.38.801]:

   1.  RAN will support differentiated handling of traffic between pre-
       configured, isolated RAN slices.  How to perform this is left to
       implementation.

   2.  Selection of the RAN slice will be based on IDs (which should be
       the slice service type and slice differentiator defined above)
       provided by the device or core network.

   3.  A RAN slice may or may not be available at a given location.

   4.  RAN will select the core network slice.

   5.  QoS differentiation within a RAN slice will be supported as well.



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4.  Management Aspect of Network Slicing in 3GPP

   3GPP is developing a Release 14 "Study on management and
   orchestration of network slicing for next generation network"
   technical report [_3GPP.28.801], which defines an information model
   where the network slice as well as physical and virtualized network
   functions belong to the network operator domain, while the
   virtualized resources belong to another domain operated by a
   virtualization infrastructure service provider.

   The concept of "sub-netslice" is used in the model, as defined
   originally in [NGMN_Network_Slicing] (we will use the term sub-
   netslices here, instead of the original subnet or sub-networks, which
   can be confusing).  Sub-netslice instances are comprised of physical
   and virtual resources, have a life cycle independent from network
   slices they belong to, can be shared between several network slices
   and may be associated with other sub-netslice instances.

   Multiple management use cases are described, ranging from creating
   and monitoring a slice instance to configuring its SLA policy,
   capacity and roaming support.  It is also expected that some level of
   slice management will be exposed to customers, and that operators
   will have the possibility to create end-to-end network slices
   involving multiple operators' networks.

   Key issues are identified, including creating a slice across multiple
   administrative domains, sharing a network slice between multiple
   services, moving towards a more autonomous management, as well as
   additional management specific key issues.

   Finally, the life cycle of a slice is defined over 4 phases:
   preparation phase including design and pre-provisioning, an
   "instantiation, configuration and activation" phase, a run-time phase
   including supervision and reporting, as well as upgrade,
   reconfiguration and scaling, and a decommissioning phase.

5.  5G Virtual Infrastructure Management in 3GPP

   To support the logical architecture defined earlier, some aspects of
   virtualization infrastructure management are also being standardized
   by 3GPP, through the activity "Management of mobile networks that
   include virtualized network functions".  This includes 5 work tasks,
   the first of which deals with concept, architecture and requirements
   [_3GPP.28.500], and 4 additional specialized work tasks on
   configuration, fault, lifecycle and performance management, are in
   the process of creating more detailed technical specification
   documents.




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   The new 5G management system is tied to NFV-MANO, as defined by ETSI.
   Its system architecture is described in [_3GPP.28.500] and
   represented in Figure 3 (directly adapted from TS28.500).  It defines
   interconnections between the 3GPP management system and the NFV-MANO
   system.  NFV-MANO has the responsibility to manage NFV Infrastructure
   (NFVI) and VNF lifecycle, and to report performance data, fault and
   VNF instance information to 3GPP management system.

   +--------------------------------------------+    +-------------+
   | +----------------------------------+OSS/BSS|    |   NFV       |(3)
   | |      NM                          |       | (1)|Orchestrator +--+
   | +--+--------------+--------------+-+       +----+   (NFVO)    |  |
   +----|--------------|--------------|---------+    +-------------+  |
        |              |              |                     |(2)      |
        | Itf-N        | Itf-N        | Itf-N               |         |
        |              |              |              +------+------+  |
        |              |              |              |             |  |
        |    +---------+------------+ |              |             |  |
        |    |DM +----------------+ | |          (5) |             |  |
        |    |   |       EM       +------------------+   VNF       |  |
        |    |   +-+--------+-----+ | |          (5) |  Manager    |  |
        |    +-----|--------|-------+ |   +----------+  (VNFM)     |  |
        |          |        |         |   |          |             |  |
        |          |        |         |   |          |             |  |
        |          |        |         |   |          |             |  |
        |          |        |         |   |          |             |  |
    +-+-+--+       |        |      +--+---++--+  (5) |             |  |
    | | EM |       |        |      | EM    |  +------+             |  |
    | +----+       |        |      +-------+  |      +------+------+  |
    |      |       |        |      |    VNF   |             |         |
    |      |  +----++  +----+----+ +----+-----+             |(4)      |
    |      |  |     |  |         |      |                   |         |
    |      |  |     |  |  VNF    |      |                   |         |
    |      |  |     |  |         |      |(7)                |         |
    |      |  |     |  +-----+---+      |            +------+------+  |
    |      |  |     |        |(7)       |            |             |  |
    |  NE  |  | NE  |  +-----+----------+----+       | Virtualized |  |
    | (PNF)|  |(PNF)|  |                     |       | Infrastruct.|  |
    |      |  |     |  | NFV Infrastructure  |  (6)  | Manager     +--+
    |      |  |     |  |     (NFVI)          +-------+  (VIM)      |
    |      |  |     |  |                     |       |             |
    +------+  +-----+  +---------------------+       +-------------+

              Figure 3: 3GPP Network Management Architecture

   The major building blocks on the left are from pre-existing 3GPP
   architecture and on the right are from ETSI NFV architecture.  Itf-N
   is the traditional 3GPP management interface between the network



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   manager and domain and element managers, some of which will now be
   collocated with VNFs.  Other interfaces identified in the diagram are
   defined as part of the NFV architecture and described in published
   NFV specifications (which themselves do not make mention of network
   slicing).

   o  (1) Os-Ma-nfvo enables managing Network Service Descriptors (NSD),
      network service lifecycle, performance, faults and VNF packages.
      The NSD information model is specified by ETSI NFV as well.  It
      enables describing network connectivity topology graphs where VNFs
      are connected together through virtual links.  An NSD also
      includes VNF descriptors, which include memory and CPU
      requirements, a link to a software image, initial setup scripts,
      etc.

   o  (2) Or-Vnfm includes package management, VNF lifecycle/fault/
      configuration management, virtualized resources management (in
      indirect mode as seen below), and relays notifications from the
      VNF or EM.

   o  (3) Or-Vi and (4) Vi-Vnfm are the northbound interface of the
      Virtual Infrastructure Manager (VIM).  The orchestrator can
      basically use a direct interface to VIM, or indirectly go through
      the VNF manager over Or-Vnfm.  The orchestrator can add software
      images, create/update/terminate virtualized compute/network/
      storage resources allocations, manage resource capacity, manage
      network virtual paths, run and query performance collection jobs,
      set quotas.  Location/affinity constraints can be applied when
      creating resources.

   o  (5) Ve-Vnfm is used both between VNFM and EM and between VNFM and
      VNFs.  It includes lifecycle, performance, fault and configuration
      management, as well as notifications from the EM that VNFM can
      subscribe to.

   o  (6) Nf-Vi is for assignment of virtualized resources, hardware
      resource configuration and state information exchange.

   o  (7) Vn-Nf represents the execution environment provided to the
      VNF.

6.  Security Considerations

   The present section on network slicing security is based on the
   "Study on Architecture and Security for Next Generation System", a
   Release 14 study item.  Its related technical report is
   [_3GPP.33.899], and covers, among other areas, a network slicing
   security area dealing with service access, network function sharing



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   and isolation.  Multiple key issues are summarized here (refer to the
   TR section 5.8 for more details):

   1.  Isolation requirements, especially performance isolation, ask for
       data plane actions on one slice to have no influence on other
       slices and for control plane actions (e.g. creation/update/
       deletion) to have little influence on other slices.  Lack of
       isolation can enable DoS attacks from one slice to another,
       especially since some functions can be shared between slices.
       Moreover, a device can access multiple slices, which increases
       the possibility for leakage/breach type of issues between slices,
       both from the device and the service side.

   2.  Different slices may need to implement different security
       policies, e.g. in term of authentication requirements (IoT vs.
       mobile broadband user).  Authentication may be centralized and/or
       per-slice.

   3.  Security and privacy of devices' access to slices is also a
       concern.  It may be possible to forge slice selection information
       for a device.  Slice selection information sent over the access
       network can also lead to confidentiality issues.  The proposed
       key hierarchy supports having different keys for different
       slices.  How to enable security isolation of a common control
       plane between different slices is not addressed at this point.

   4.  Security of sensitive shared network elements such as the HSS
       (which holds customers' profiles) is identified as a key issue as
       well.

   5.  Slice management functions should be secured, since an attacker
       may use them, e.g. to delete a slice.  Slice management
       capabilities exposed through APIs for 3rd parties are especially
       vulnerable.

   6.  Security on inter-slice communications is an issue in several
       scenarios, for example when multiple slices share control plane
       functions, and when a RAN slice and a core network slice are
       interconnected to form a complete slice.  Each slice is
       considered a different trusted domain.

   7.  A range of potential issues related to virtualization are yet to
       be explored further, though it is not clear if they are in the
       scope of 3GPP.  Issues include for example isolation between VNFs
       hosted by the same hypervisor, authentication between VNFs,
       performance isolation between VNFs.





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7.  Conclusion

   This document summarized our understanding of 5G architecture and
   requirements for network slicing, as defined by 3GPP, in their
   current state.  Our goal was to provide context to IETF NETSLICES,
   since a protocol or framework defined by IETF for network slicing may
   be used to implement or interoperate with 3GPP-compliant 5G systems.
   In reference to Figure 3, the scope of IETF involvement with network
   slicing could be within NFV Infrastructure, as well as some aspects
   of the control plane on the right-hand side of the figure.

   Here is a list of discussion points gathered while preparing this
   document, in no particular order:

   1.  The concept of "sub-netslice" in section 4 may be useful as a
       building block, e.g. a single-domain, indivisible and composable
       service chain that is used to assemble a network slice.  Defining
       the interfaces of such a component could help focusing on sharing
       between slices and extending slices across domains.

   2.  A large portion of the NS-related logical architecture agreements
       so far is focusing on network slice instance selection. 3GPP
       architecture demonstrate a requirement for common authentication
       and network slice selection functions.  It is our understanding
       that the described mechanism enables a wide variation of cases
       associating "n" slices with "m" network services or applications
       involving "p" end devices.  For example: a single slice instance
       could be associated with multiple IoT applications, each
       connected to multiple devices.  In another example, an
       application may split its end users in 2 service categories with
       different SLAs, using different network slice instances.

   3.  Interoperation between slices is a major risk factor on isolation
       and can occur in various scenarios:

       *  "Interoperation for extension" when data and control plane are
          interconnected for extending a slice between RAN and CN, or
          between visitor and home networks in a roaming scenario.

       *  "Interoperation through network function sharing" occurs in
          3GPP when some control planes functions are performed by
          common functions.

       *  "Interoperation through end points" can occur on user devices
          connected to multiple network slices, or on an application
          server side interacting with clients over different slices.





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   4.  Sharing and interoperation within slices is also a concern and
       occurs at multiple levels: QoS differentiation within a given
       slice, and sharing a single slice between multiple services.
       Deployment of a single slice over multiple data centers is not an
       explicitly described scenario but may possibly be implied by the
       use of virtualization of core network function.

   5.  Managing and deploying 3rd party network services is a potential
       use case for network slicing.  For example, network slice
       management will likely be partially exposed to customers.
       Additionally, an early requirement, that was finally not included
       in the 3GPP specifications for network slicing, mentioned
       "hosting multiple 3rd parties (e.g., enterprises) or MVNOs".

   6.  There is a strict requirement for security and performance
       isolation from data plane and control plane actions between
       slices.  Should network slices be allowed to tap into currently
       unused resource capacity?  There is a possible tradeoff here
       between performance/network efficiency and isolation, since in
       this case, through its normal operation, a slice may influence
       another slice by denying it this extra capacity.

   7.  Beyond performance isolation, there are multiple security
       concerns related to network slicing, including the need for
       separate per-netslice security policies.

   We hope these points will contribute to the ongoing discussion taking
   place in IETF NETSLICES to define requirements and work areas related
   to network slicing.

8.  IANA Considerations

   This document requests no IANA actions.

9.  Acknowledgements

   The authors would like to thank Ulises Olvera-Hernandez for his
   contribution and comments.

10.  Informative References

   [_3GPP.22.261]
              3GPP, "Service requirements for next generation new
              services and markets", 3GPP TS 22.261 1.1.0, February
              2017, <http://www.3gpp.org/ftp/Specs/html-info/22261.htm>.






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   [_3GPP.23.401]
              3GPP, "General Packet Radio Service (GPRS) enhancements
              for Evolved Universal Terrestrial Radio Access Network
              (E-UTRAN) access", 3GPP TS 23.401 14.2.0, 12 2016,
              <http://www.3gpp.org/ftp/Specs/html-info/23401.htm>.

   [_3GPP.23.501]
              3GPP, "System Architecture for the 5G System", 3GPP
              TS 23.501 0.2.0, 2 2017,
              <http://www.3gpp.org/ftp/Specs/html-info/23501.htm>.

   [_3GPP.23.799]
              3GPP, "Study on Architecture for Next Generation System",
              3GPP TR 23.799 14.0.0, 12 2016,
              <http://www.3gpp.org/ftp/Specs/html-info/23799.htm>.

   [_3GPP.28.500]
              3GPP, "Telecommunication management; Management concept,
              architecture and requirements for mobile networks that
              include virtualized network functions", 3GPP TS 28.500
              1.3.0, 11 2016,
              <http://www.3gpp.org/ftp/Specs/html-info/28500.htm>.

   [_3GPP.28.801]
              3GPP, "Study on management and orchestration of network
              slicing for next generation network", 3GPP TR 28.801
              0.4.0, 1 2017,
              <http://www.3gpp.org/ftp/Specs/html-info/28801.htm>.

   [_3GPP.33.899]
              3GPP, "Study on the security aspects of the next
              generation system", 3GPP TR 33.899 0.6.0, 11 2016,
              <http://www.3gpp.org/ftp/Specs/html-info/33899.htm>.

   [_3GPP.38.801]
              3GPP, "Study on the security aspects of the next
              generation system", 3GPP TR 38.801 1.0.0, 12 2016,
              <http://www.3gpp.org/ftp/Specs/html-info/38801.htm>.

   [I-D.gdmb-netslices-intro-and-ps]
              Galis, A., Dong, J., kiran.makhijani@huawei.com, k.,
              Bryant, S., Boucadair, M., and P. Martinez-Julia, "Network
              Slicing - Introductory Document and Revised Problem
              Statement", draft-gdmb-netslices-intro-and-ps-02 (work in
              progress), February 2017.






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   [NGMN_Network_Slicing]
              NGMN, "Description of Network Slicing Concept", 1 2016,
              <https://www.ngmn.org/uploads/
              media/160113_Network_Slicing_v1_0.pdf>.

Authors' Addresses

   Xavier de Foy
   InterDigital Communications, LLC
   Montreal
   Canada

   Email: Xavier.Defoy@InterDigital.com


   Akbar Rahman
   InterDigital Communications, LLC
   Montreal
   Canada

   Email: Akbar.Rahman@InterDigital.com






























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