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Versions: 00 01                                                         
TEAS                                                       LM. Contreras
Internet-Draft                                                Telefonica
Intended status: Informational                                  R. Rokui
Expires: August 26, 2021                                           Nokia
                                                             J. Tantsura
                                                                  Apstra
                                                                   B. Wu
                                                                  Huawei
                                                                  X. Liu
                                                                   Volta
                                                                D. Dhody
                                                                  Huawei
                                                              S. Belloti
                                                                   Nokia
                                                       February 22, 2021


      IETF Network Slice Controller and its associated data models
            draft-contreras-teas-slice-controller-models-01

Abstract

   This document describes the major functional components of an IETF
   Network Slice Controller (NSC) as well as references the data models
   required for supporting the requests of IETF network slices and their
   realization.

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
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   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 August 26, 2021.








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Copyright Notice

   Copyright (c) 2021 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
   (https://trustee.ietf.org/license-info) in effect on the date of
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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.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  IETF Network Slice data models  . . . . . . . . . . . . . . .   3
   3.  Structure of the IETF Network Slice Controller (NSC)  . . . .   4
     3.1.  NS Mapper . . . . . . . . . . . . . . . . . . . . . . . .   7
     3.2.  NS Realizer . . . . . . . . . . . . . . . . . . . . . . .   7
   4.  Model types in IETF Network Slice Controller interfaces . . .   7
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   9

1.  Introduction

   Editor's Note: the terminology in this draft will be aligned with the
   final terminology selected for describing the notion of IETF Network
   Slice when applied to IETF technologies, which is currently under
   discussion.  By now same terminology as used in
   [I-D.nsdt-teas-ietf-network-slice-definition] and
   [I-D.nsdt-teas-ns-framework] is primarily used here.  Consensus to
   use "IETF Network Slice" term has been reached.

   The generic idea of network slicing intends to provide tailored end-
   to-end network capabilities to customers in the way that they could
   be perceived as a dedicated network, despite the fact that it makes
   use of shared physical infrastructure facilities.

   Among the capabilities mentioned, connectivity of different parts of
   a network slice with particular characteristics play a central role.
   Thus, the concept of IETF Network Slice, realized by any of the IETF
   technologies, emerges as complementary but essential part of an end-
   to-end network slice.



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   In order to facilitate the request, realization and lifecycle control
   and management of a transport slice, a new element named IETF Network
   Slice Controller (NSC) is being proposed in
   [I-D.nsdt-teas-ietf-network-slice-definition] and
   [I-D.nsdt-teas-ns-framework].

   The NSC from its North Bound Interface (NBI) exposes set of APIs that
   allow a higher level system to request an end-to-end transport slice.
   It receives the request of enablement of an IETF Network Slice by a
   customer (i.e. creation, modification or deletion).  Upon receiving a
   request from its NBI, NSC finds the resources needed for realization
   of the IETF Network Slice and in turn interfaces from its South Bound
   Interface (SBI) with one or more Network Controllers for the
   realization of the requested IETF Network Slice request and the
   management of its lifecycle.  Figure 1 presents a high-level view of
   the TSC.


                   +------------------------------------------+
                   |         A higher level system            |
                   |   (e.g E2E network slice orchestrator)   |
                   +------------------------------------------+
                                        A
                                        | NSC NBI
                                        V
                   +------------------------------------------+
                   |   IETF Network Slice Controller (NSC)    |
                   +------------------------------------------+
                                        A
                                        | NSC SBI
                                        V
                   +------------------------------------------+
                   |           Network Controller(s)          |
                   +------------------------------------------+

             Figure 1: Interface of Transport Slice Controller

   This memo describes the characteristics of the NSC as well as a
   detailed structure of the NSC and its major components.  In addition,
   it describes the characteristics of the data models to identify the
   IETF Network Slice and its realization.  Then the data models
   referred are mapped to the interfaces among components.

2.  IETF Network Slice data models

   At the time of provisioning and operating IETF Network Slices
   different views can be identified as necessary:




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   o  Customer's view, mostly focused on the individual IETF Network
      Slice request process, reflecting the needs of each particular
      customer, including SLOs and other characteristics of the slice
      relevant for it.  This view is technology agnostics and describes
      the characteristics of the IETF Network Slice from a customer's
      point of view.  It can include the slice topology, performance
      parameters, endpoints of the slice, traffic characteristics of the
      slice, and the KPIs to monitor the slice.

   o  Provider's view, mostly focused on the provisioning and operation
      of the IETF Network Slices in the transport network, considering
      how a particular IETF Network Slice interplays with other IETF
      Network Slices maintained by the provider on a shared
      infrastructure.  In other words, operator's view shows how an IETF
      Network Slice is realized in operator's network along with all the
      resources used during the its realization.

   Both views are complementary, each of them specialized for a given
   purpose.  In consequence, it should be consistency between both in
   order to ensure alignment.

   Currently there are two different models proposed, on for each of the
   categories above.  The model in
   [I-D.wd-teas-ietf-network-slice-nbi-yang] fits into the customer
   view, while the model defined in
   [I-D.liu-teas-transport-network-slice-yang] fits in to the provider
   view.

   It should be noted that for the realization of a transport slice, the
   NSC interacts with one or more Network Controllers.  In that case,
   the data models to be used are particular for each Network Controller
   (e.g., technology dependent), as well as the mapping function from
   its NBI to SBI and the details of this mapping function are both out
   of the scope of this document.

3.  Structure of the IETF Network Slice Controller (NSC)

   The NSC should work with both data models.  The NSC takes first the
   customer's view by analyzing the needs of the customer, processing
   such requests taking into account the overall view of the network and
   the IETF Network Slices already instantiated, normalizing its
   instantiation across different technologies, and finally generates
   the provider view.

   Once the new request is processed and declared as feasible, the NSC
   triggers its realization by interacting with the Network Controllers
   and communicates back to the higher level controller to start the
   billing cycle.



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   In order to accommodate these procedures, the internal structure of
   the NSC can be divided into:

   o  IETF Network Slice Mapper: this high-level component processes the
      customer request, putting it into the context of the overall IETF
      Network Slices in the network.

   o  IETF Network Slice Realizer: this high-level component processes
      the complete view of transport slices including the one requested
      by the customer, decides the proper technologies for realizing the
      IETF Network Slice and triggers its realization.

   Figure 2 illustrates the components described and the associated
   models, as follows

   o  (a) -> customer's view, e.g.
      [I-D.wd-teas-ietf-network-slice-nbi-yang].

   o  (b) -> provider's view, e.g.
      [I-D.liu-teas-transport-network-slice-yang].

   o  (c) -> models per network controller, out of scope of this
      document




























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                                    Higher Level System
                                             |
                                             |
                                ---------------------------
                                | NSC        | (a)        |
                                |            v            |
                                |   -------------------   |
                                |   |                 |   |
                                |   |    NS Mapper    |   |
                                |   |                 |   |
                                |   -------------------   |
                                |            | (b)        |
                                |            v            |
                                |   -------------------   |
                                |   |                 |   |
                                |   |    NS Realizer  |   |
                                |   |                 |   |
                                |   -------------------   |
                                |            | (c)        |
                                ---------------------------
                                             |
                                             v
                                    Network Controllers

     Figure 2: IETF Network Slice Controller structure and asspociated
                                data models

   IETF Network Slices with different level of detail could be
   requested:

   o  The IETF network slice can be abstracted as a set of edge-to-edge
      links (Type 1).

   o  The IETF network slice can be abstracted as a topology of virtual
      nodes and virtual links (Type 2) which represent the partitioning
      of underlay network resources for use by network slice
      connectivity.

   The use cases of these two types of networks are further described by
   [RFC8453].  [I-D.wd-teas-ietf-network-slice-nbi-yang] models the Type
   1 service, while [I-D.liu-teas-transport-network-slice-yang] models
   the Type 2 service.  When a customer intends to request a Type 2
   service, [I-D.liu-teas-transport-network-slice-yang] can also be used
   at the point (a) in Figure 2.  As an example, when ACTN is used to
   realize an IETF network slice, model mappings are described in more
   details in [I-D.ietf-teas-actn-yang].





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3.1.  NS Mapper

   The Mapper will receive the IETF Network Slice request from the
   customer.  It will process it obtaining an overall view of how this
   new request complements or fits with the rest of IETF Network Slices,
   if any, as provisioned in the network.  As part of that processing, a
   single customer IETF Network Slice request could result in the need
   of actually provisioning different IETF Network Slices in the
   network.  The Mapper will maintain the relationship among customer
   IETF Network Slice request and provisioned IETF Network Slices.

3.2.  NS Realizer

   The Realizer will receive from the Mapper one or more requests for
   provision of IETF Network Slices, potentially including some
   technology-specific information.  With that information, the Realizer
   will determine the realization of each particular IETF Network Slice
   interacting with technology-specific Network Controllers.

4.  Model types in IETF Network Slice Controller interfaces

   Both [RFC8309] and [RFC8969] offer a complete view of customer,
   service and network model types.  In this sense a potential mapping
   of models to IETF Network Slcie Controller interfaces is as follows:

   o  NBI of the IETF NSC (interface (a) in Figure 2) -> Customer
      service model.  According to [RFC8309] "a customer's service
      request is (or should be) technology agnostic.  That is, a
      customer is unaware of the technology that the network operator
      has available to deliver the service, so the customer does not
      make requests specific to the underlying technology but is limited
      to making requests specific to the service that is to be
      delivered".  This definition matches the expected behavior of the
      IETF NSC NBI as considered in in
      [I-D.nsdt-teas-ietf-network-slice-definition] and
      [I-D.nsdt-teas-ns-framework].

   o  Interface between NS Mapper and NS Realizer (interface (b) in
      Figure 2) -> Service Delivery model.  According to [RFC8309] "a
      service delivery module is expressed as a core set of parameters
      that are common across a network type and technology [...] Service
      delivery modules include technology-specific modules.".
      Furthermore, [RFC8969] (in its Figures 3 and 5) considers L3SM or
      VN Service models to be later on fed into a controller.

   o  SBI of the IETF NSC (interface (c) in Figure 2) -> Network
      Configuration model.  According to [RFC8309] "the orchestrator
      must map the service request to its view, and this mapping may



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      include a choice of which networks and technologies to use
      depending on which service features have been requested".  This is
      coincideent with the expected behavior of the IETF NSC SBI as
      considered in in [I-D.nsdt-teas-ietf-network-slice-definition] and
      [I-D.nsdt-teas-ns-framework].

5.  Security Considerations

   To be done.

6.  IANA Considerations

   This draft does not include any IANA considerations

7.  References

   [I-D.ietf-teas-actn-yang]
              Lee, Y., Zheng, H., Ceccarelli, D., Yoon, B., Dios, O.,
              Shin, J., and S. Belotti, "Applicability of YANG models
              for Abstraction and Control of Traffic Engineered
              Networks", draft-ietf-teas-actn-yang-06 (work in
              progress), August 2020.

   [I-D.liu-teas-transport-network-slice-yang]
              Liu, X., Tantsura, J., Bryskin, I., Contreras, L., WU, Q.,
              Belotti, S., and R. Rokui, "IETF Network Slice YANG Data
              Model", draft-liu-teas-transport-network-slice-yang-02
              (work in progress), November 2020.

   [I-D.nsdt-teas-ietf-network-slice-definition]
              Rokui, R., Homma, S., Makhijani, K., Contreras, L., and J.
              Tantsura, "Definition of IETF Network Slices", draft-nsdt-
              teas-ietf-network-slice-definition-02 (work in progress),
              December 2020.

   [I-D.nsdt-teas-ns-framework]
              Gray, E. and J. Drake, "Framework for Transport Network
              Slices", draft-nsdt-teas-ns-framework-04 (work in
              progress), July 2020.

   [I-D.wd-teas-ietf-network-slice-nbi-yang]
              Bo, W., Dhody, D., Han, L., and R. Rokui, "A Yang Data
              Model for IETF Network Slice NBI", draft-wd-teas-ietf-
              network-slice-nbi-yang-01 (work in progress), November
              2020.






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   [RFC8309]  Wu, Q., Liu, W., and A. Farrel, "Service Models
              Explained", RFC 8309, DOI 10.17487/RFC8309, January 2018,
              <https://www.rfc-editor.org/info/rfc8309>.

   [RFC8453]  Ceccarelli, D., Ed. and Y. Lee, Ed., "Framework for
              Abstraction and Control of TE Networks (ACTN)", RFC 8453,
              DOI 10.17487/RFC8453, August 2018,
              <https://www.rfc-editor.org/info/rfc8453>.

   [RFC8969]  Wu, Q., Ed., Boucadair, M., Ed., Lopez, D., Xie, C., and
              L. Geng, "A Framework for Automating Service and Network
              Management with YANG", RFC 8969, DOI 10.17487/RFC8969,
              January 2021, <https://www.rfc-editor.org/info/rfc8969>.

Authors' Addresses

   Luis M. Contreras
   Telefonica
   Ronda de la Comunicacion, s/n
   Sur-3 building, 3rd floor
   Madrid  28050
   Spain

   Email: luismiguel.contrerasmurillo@telefonica.com
   URI:   http://lmcontreras.com/


   Reza Rokui
   Nokia
   Canada

   Email: reza.rokui@nokia.com


   Jeff Tantsura
   Apstra
   USA

   Email: jefftant.ietf@gmail.com


   Bo Wu
   Huawei Technologies
   101 Software Avenue, Yuhua District
   Nanjing, Jiangsu  210012
   China

   Email: lana.wubo@huawei.com



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   Xufeng Liu
   Volta Networks

   Email: xufeng.liu.ietf@gmail.com


   Dhruv Dhody
   Huawei Technologies
   Divyashree Techno Park
   Bangalore, Karnataka  560066
   India

   Email: dhruv.ietf@gmail.com


   Sergio Belloti
   Nokia

   Email: sergio.belotti@nokia.com
































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