No Working Group                                                A. Galis
Internet-Draft                                 University College London
Intended status: Informational                                   J. Dong
Expires: July 23, 2017                                      K. Makhijani
                                                               S. Bryant
                                                     Huawei Technologies
                                                        January 19, 2017


 Network Slicing - Introductory Document and Revised Problem Statement
                  draft-gdmb-netslices-intro-and-ps-00

Abstract

   This documents represents an introduction to the motivation and
   Network Slicing problems and work ares.  It represents an initial
   revision of Network Slicing problem statement derived from the
   analysis of the technical gaps in IETF protocols ecosystem.  It
   complements and it bring together the isolated efforts being carried
   out in several IETF working groups to achieve certain aspects of
   network slice functions and operations.

Status of This Memo

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   publication of this document.  Please review these documents



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   carefully, as they describe your rights and restrictions with respect
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Notes . . . . . . . . . . . . . . . . . . . . . . . . . .   4
   2.  Suggested Problems and Work Areas . . . . . . . . . . . . . .   4
     2.1.  Notes . . . . . . . . . . . . . . . . . . . . . . . . . .   6
   3.  Documents . . . . . . . . . . . . . . . . . . . . . . . . . .   7
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   7
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   8
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   8
     7.2.  Informative References  . . . . . . . . . . . . . . . . .   9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  10

1.  Introduction

   Network slicing (NS) refers to the managed partitions of physical
   and/or virtual network resources, network physical/virtual and
   service functions that can act as an independent instance of a
   network and/or as a network cloud.  Network resources include
   connectivity, compute and storage resources.

   Slices considerably transform the networking perspective by
   abstracting, isolating, orchestrating, softwarizing and separating
   logical network components from the underlying physical network
   resources and as such they enhance Internet architecture.

   For slice creation, the management plane creates the grouping of
   physical and virtual network resources, connects with the physical
   and virtual network and service functions as appropriate and it
   instantiates all the network and service functions assigned to the
   slice.  On the other hand for slice operations the slice control
   takes over the control and governing of all the network resources,
   network functions and service functions assigned to the slice, and
   (re-) configure them as appropriate and as per elasticity needs in
   order to provide an end-to-end service.

   Network operators can exploit NS to significantly reduce operations
   expenditures, and enable softwarization, programmability and the
   innovation necessary to enrich the offered services.  Network
   softwarization techniques [IMT2020-2015], [IMT2020-2016] may be used



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   to realised and manage [MANO-2014] network slicing.  NS provides the
   means for the network operators to provide network programmable
   capabilities to OTT providers and other market players without
   changing their physical infrastructure.  NS enables the concurrent
   deployment of multiple logical, self-contained and independent,
   shared or partitioned networks on a common infrastructure.  Slices
   support also dynamic multi-services, multi-tenancy and the
   integration means for vertical market players.

   The purpose of NS work in IETF is to develop a set of protocols and/
   or protocol extensions that enable efficient slice creation,
   activation / deactivation, composition, elasticity, orchestration,
   management, isolation, guaranteed SLA and safe operations within a
   network or network cloud / data centre environment that assumes an IP
   and/or MPLS-based underlay.

   While there are, isolated efforts being carried out in several IETF
   working groups DETNET, [I-D.leeking-actn-problem-statement],
   [I-D.dong-network-slicing-problem-statement],
   [I-D.galis-anima-autonomic-slice-networking], [IETF-Slicing1],
   [IETF-Slicing2], [IETF-Slicing3], [IETF-Slicing4], [IETF-Slicing5] to
   achieve certain aspects of network slice functions and operations,
   there is a clear need to look at complete life-cycle management
   characteristics of network Slicing solutions though the discussions
   based on the following architectural tenets:

   o Underlay tenet: support for an IP/MPLS-based underlay data plane
   the transport network used to carry that underlay.

   o Governance tenet: a logically centralized authority for network
   slices in a domain.

   o Separation tenet: slices are independent and have appropriate
   degree of isolation (1) from each other.

   o Capability exposure tenet: each slice allows third parties to
   access via APIs information regarding services provided by the slice
   (e.g. connectivity information, QoS, mobility, autonomicity, etc.)
   within the limits set by the operator.

   NS approaches that do not adhere to these tenets are explicitly
   outside of the scope of the proposed work at IETF.

   In pursuit of the solutions described above, there is a need to
   document an architecture for network slicing within both wide area
   network and a data center environments.





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   Elicitation of requirements ([RFC2119], [RFC4364]) for a network
   slice control and management planes and will be needed facilitating
   the selection, extension, and/or development of the protocol for each
   of the functional interfaces identified to support the architecture.

   Additionally, documentation on the common use-cases for slice
   validation for 5G is needed (e.g. mission-critical ultra-low latency
   communication services; massive-connectivity machine communication
   services - smart metering, smart grid and sensor networks; extreme
   QoS; Independent operations and management; Independent cost and/or
   energy optimisation; Independent multi-topology routing; multi-tenant
   operations, etc.).

   The proposed NS work would be co-ordinated with other IETF WGs (e.g.
   TEAS WG, DETNET WG, ANIMA WG, NETCONF WG, SUPA WG, NVO3 WG, Routing
   Area WG (RTGWG), Network Management Research Group (NMRG) and NFV
   Research Group (NFVRG)) to ensure that the commonalities and
   differences in solutions are properly considered.  Where suitable
   protocols, models or methods exist, they will be preferred over
   creating new ones.

1.1.  Notes

   (1) This issue require efficient interaction between an upper layer
   in the hierarchy and a lower layer for QoS guaranties and most of the
   operations on slicing.

2.  Suggested Problems and Work Areas

   The goal of this work is to develop one or more protocol
   specifications (or extensions to existing protocols) to address the
   following problem areas.  These problems were selected according to
   the analysis of the technical gaps in IETF protocols ecosystem.

   o Uniform Reference Model for Network Slicing; Describe all elements
   and instances of a network slice.  Describe shared non-sliced network
   parts.

   o Slice Templates: Design the slices to different scenarios
   ([ChinaCom-2009], [GENI-2009], [IMT2020-2016bis], [NGMN-2016],
   [NGS-3GPP-2016], [ONF-2016]); an appropriate slice template
   definition that may include capability exposure of managed partitions
   of physical and/or virtual network resources (i.e.  connectivity,
   compute and storage resources), physical and/or virtual network and
   service functions that can act as an independent network and/or as a
   network cloud.





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   o Network slice expected capabilities (i.e. prioritization may be
   needed):

       * Four-dimensional efficient slice isolation with guarantees for
         isolation in Data / Control / Management / Service planes.
         Enablers for safe and efficient multi-tenancy in slices.

       * Methods to guarantee the end-to-end QoS of a slice.

       * Recursion - methods for NS segmentation allowing a slicing
         hierarchy with parent child relationships.

       * Efficiency in slicing: realize diverse requirements without
         re-engineering the infrastructure.

       * Customized security mechanisms per slice.

       * Enablers to manage the trade-offs between flexibility and
         efficiency in slicing.

       * Optimisation - methods for network resources automatic
         acquisition, global resource view formed; global energy view
         formed; Network Slice deployed based on global resource
         and energy efficiency; Mapping algorithms.

       * Monitoring status and behaviour of NS in a single and/or
         muti-domain environment.

       * Capability exposure for slices; APIs for slices.

       * Programmability and openness of network slices.

   o Network slice operations (i.e. prioritization may be needed):


















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    * Slice creation: slices in access, core and transport
      networks; slices in data centres, slices in edge clouds.

    * Slice life cycle management including creation,
      activation/ deactivation, protection (2) , elasticity (3),
      extensibility (4) , safety (5) , Sizing and
      scalability of the slicing model per network and
      per network cloud.

    * Autonomic slice management and operation (i.e. self-configuration,
      self-composition, self-monitoring, self-optimisation,
      self-elasticity are carried as part of the slice protocols).

    * Slice stitching / composition: Enablers for efficient stitching /
      composition/ decomposition of slices:

        - vertically (service + management + control planes) and/or
        - horizontally (between different domains part of access,
          core, edge segments) and /or
        - vertically + horizontally.

    * E2E wireline network segments and network clouds orchestration
      of slices ([GUERZONI-2016], [KARL-2016]).

    * Service Mapping: Dynamic Mapping of Services to slices; YANG
      models for slices.

   o Efficient enablers for Integration of above capabilities and
   operations.

2.1.  Notes

   (2) Protection refers to the related mechanisms so that events within
   one slice, such as congestion, do not have a negative impact on
   another slice.

   (3) Elasticity refers to the mechanisms and triggers for the growth
   /shrinking of network resources, network and service functions.

   (4) Extensibility refers to the ability to expand a NS with
   additional functionality and/or characteristics or through
   modification of existing functionality/characteristics, while
   minimizing impact to existing functions.

   (5) Safety refers to the conditions of being protected against
   different types and the consequences of failure, error harm or any
   other event, which could be considered non-desirable.




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   [GUERZONI-2016] [KARL-2016]

3.  Documents

   The following are the proposed / expected / resulting documents with
   priority (I) or (II) (i.e. revised prioritization may be needed):

   o Agreed work plan

   o Slice template and reference model to IESG (Informational)

   o Slice life-cycle management model to IESG (Informational)

   o Requirements for a network slice control and management planes.

   o Common use-cases for slice validation for 5G

   o (I) Slice template and reference model.

   o (I) Four dimensional efficient slice isolation with guarantees for
   isolation in Data/ Control/ Management/ Service planes.

   o (II) Methods to guarantee the end-to-end QoS of a slice.

   o (I) YANG data model for slicing.

   o (I) E2E orchestration of slices.

   o (II) Customized security mechanisms per slice.

   o (I) Slice stitching / composition: enablers for efficient stitch /
   composition / decomposition of slices vertically, horizontally and
   vertically + horizontally

4.  Security Considerations

   Security will be a major part of the design of network slicing.

5.  IANA Considerations

   This document requests no IANA actions.

6.  Acknowledgements

   Thanks to Sheng Jiang (Huawei Technologies) for reviewing this draft.






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7.  References

7.1.  Normative References

   [I-D.dong-network-slicing-problem-statement]
              Dong, J. and S. Bryant, "Problem Statement of Network
              Slicing in IP/MPLS Networks", draft-dong-network-slicing-
              problem-statement-00 (work in progress), October 2016.

   [I-D.galis-anima-autonomic-slice-networking]
              Galis, A., Makhijani, K., and D. Yu, "Autonomic Slice
              Networking-Requirements and Reference Model", draft-galis-
              anima-autonomic-slice-networking-01 (work in progress),
              October 2016.

   [I-D.leeking-actn-problem-statement]
              Lee, Y., King, D., Boucadair, M., Jing, R., and L.
              Contreras, "Problem Statement for Abstraction and Control
              of Transport Networks", draft-leeking-actn-problem-
              statement-03 (work in progress), September 2014.

   [IETF-Slicing1]
              "Presentations - Network Slicing meeting at IETF 97 of
              15th November 2016", n.d., <https://www.dropbox.com/s/ax2o
              fdwygjema8z/0-Network%20Slicing%20Side%20Meeting%20Introdu
              ction_IETF97.pdf>.

   [IETF-Slicing2]
              "Presentations - Network Slicing meeting at IETF 97 of
              15th November 2016", n.d., <https://www.dropbox.com/s/k2or
              6sd0ddzrc6c/1-Network%20Slicing%20Problem%20Statement_IETF
              97.pdf>.

   [IETF-Slicing3]
              "Presentations - Network Slicing meeting at IETF 97 of
              15th November 2016", n.d., <https://www.dropbox.com/s/g8zv
              fvbrtkysjs1/2-Autonomic%20Slice%20Networking_IETF97.pdf>.

   [IETF-Slicing4]
              "Presentations - Network Slicing meeting at IETF 97 of
              15th November 2016", n.d., <https://www.dropbox.com/s/d3rk
              4pjeg552ilv/3-Architecture%20for%20delivering%20multicast%
              20mobility%20services%20using%20network%20slicing_IETF97.p
              df>.







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   [IETF-Slicing5]
              "Presentations - Network Slicing meeting at IETF 97 of
              15th November 2016", n.d., <https://www.dropbox.com/s/e3is
              n1bxwwhaw8g/4-ACTN%20and%20network%20slicing_IETF97.pdf>.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <http://www.rfc-editor.org/info/rfc2119>.

   [RFC4364]  Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private
              Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364, February
              2006, <http://www.rfc-editor.org/info/rfc4364>.

7.2.  Informative References

   [ChinaCom-2009]
              "A. Galis et al - Management and Service-aware Networking
              Architectures (MANA) for Future Internet - Invited paper
              IEEE 2009 Fourth International Conference on
              Communications and Networking in China (ChinaCom09) 26-28
              August 2009, Xi'an, China", n.d.,
              <http://www.chinacom.org/2009/index.html>.

   [GENI-2009]
              "GENI Key Concepts - Global Environment for Network
              Innovations (GENI)", n.d.,
              <http://groups.geni.net/geni/wiki/GENIConcepts>.

   [GUERZONI-2016]
              "Guerzoni, R., Vaishnavi,I.,Perez-Caparros, D., Galis, A.,
              et al Analysis of End-to-End Multi Domain Management and
              Orchestration Frameworks for Software Defined
              Infrastructures - an Architectural Survey", June 2016,
              <onlinelibrary.eiley.com/10.1002/ett.3084/pdf>.

   [IMT2020-2015]
              "Report on Gap Analysis", ITU-T FG IMT2020 , December
              2015, <http://www.itu.int/en/ITU-T/focusgroups/imt-
              2020/Pages/default.aspx>.

   [IMT2020-2016]
              "Draft Technical Report Application of network
              softwarization to IMT-2020 (O-041)", ITU-T FG IMT2020 ,
              December 2016, <http://www.itu.int/en/ITU-T/focusgroups/
              imt-2020/Pages/default.aspx>.





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   [IMT2020-2016bis]
              "Draft Terms and definitions for IMT-2020 in ITU-T
              (O-040)", ITU-T FG IMT2020 , December 2016,
              <http://www.itu.int/en/ITU-T/focusgroups/imt-2020/Pages/
              default.aspx>.

   [KARL-2016]
              "Karl, H., Peuster, M, Galis, A., et al DevOps for Network
              Function Virtualization - An Architectural Approach", July
              2016,
              <http://onlinelibrary.wiley.com/doi/10.1002/ett.3084/
              full>.

   [MANO-2014]
              "Network Functions Virtualisation (NFV); Management and
              Orchestration v1.1.1.", ETSI European Telecommunications
              Standards Institute. , December 2014,
              <http://www.etsi.org/deliver/etsi_gs/NFV-
              MAN/001_099/001/01.01.01_60/gs_nfv-man001v010101p.pdf>.

   [NGMN-2016]
              "Hedmar,P., Mschner, K., et al - Description of Network
              Slicing Concept", NGMN Alliance NGS-3GPP-2016 , January
              2016, <https://www.ngmn.org/uploads/
              media/160113_Network_Slicing_v1_0.pdf>.

   [NGS-3GPP-2016]
              "Study on Architecture for Next Generation System - latest
              version v1.0.2", September 2016,
              <http://www.3gpp.org/ftp/tsg_sa/WG2_Arch/Latest_SA2_Specs/
              Latest_draft_S2_Specs>.

   [ONF-2016]
              "Paul, M, Schallen, S., Betts, M., Hood, D., Shirazipor,
              M., Lopes, D., Kaippallimalit, J., - Open Network
              Fundation document "Applying SDN Architecture to 5G
              Slicing", Open Network Fundation , April 2016,
              <https://www.opennetworking.org/images/stories/downloads/
              sdn-resources/technical-reports/
              Applying_SDN_Architecture_to_5G_Slicing_TR-526.pdf>.

Authors' Addresses

   Alex Galis
   University College London

   Email: a.galis@ucl.ac.uk




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   Jie Dong
   Huawei Technologies

   Email: jie.dong@huawei.com


   Kiran Makhijani
   Huawei Technologies

   Email: kiran.makhijani@huawei.com


   Stewart Bryant
   Huawei Technologies

   Email: stewart.bryant@gmail.com



































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