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Versions: 00 01                                                         
CCAMP Working Group                                       Haomian Zheng
Internet Draft                                               Italo Busi
Intended status: Standard Track                     Huawei Technologies
                                                              Aihua Guo
                                                 Futurewei Technologies
                                                            Victor Lopez
                                                    Telefonica I+D/GCTO

Expires: August 2021                                  February 22, 2021


             Framework and Data Model for OTN Network Slicing
                   draft-zheng-ccamp-yang-otn-slicing-01


Abstract

   The requirement of slicing network resource with desired quality of
   service is emerging at every network technology, including the
   Optical Transport Networks (OTN). As a part of the transport network,
   OTN can provide hard pipes with guaranteed data isolation and
   deterministic low latency, which are highly demanded in the Service
   Level Agreement (SLA).

   This document describes a framework for OTN network slicing and a
   YANG data model augmentation of the OTN topology model. Additional
   YANG data model augmentations will be defined in a future version of
   this draft.

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), its areas, and its working groups.  Note that
   other groups may also distribute working documents as Internet-
   Drafts.

   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."

   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/ietf/1id-abstracts.txt





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   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html

   This Internet-Draft will expire on August 22, 2021.

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
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document. Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document. Code Components extracted from this document must
   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...................................................3
   2. Use Cases for OTN Network Slicing..............................3
      2.1. Leased Line Services with OTN.............................3
      2.2. Co-construction and Sharing...............................3
      2.3. Wholesale of optical resources............................4
      2.4. Vertical dedicated network with OTN.......................4
   3. Framework for OTN slicing......................................5
   4. YANG Data Model for OTN Slicing Configuration..................7
      4.1. OTN Slicing YANG Model for MPI............................7
         4.1.1. MPI YANG Model Overview..............................7
         4.1.2. MPI YANG Model Tree..................................7
         4.1.3. MPI YANG Code........................................7
      4.2. OTN Slicing YANG Model for OTN-SC NBI....................11
   5. Manageability Considerations..................................11
   6. Security Considerations.......................................11
   7. IANA Considerations...........................................11
   8. References....................................................12
      8.1. Normative References.....................................12
      8.2. Informative References...................................12
   Acknowledgments..................................................12
   Contributors' Addresses..........................................12
   Authors' Addresses...............................................13





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1. Introduction

   The requirement of slicing network resource with desired quality of
   service is emerging at every network technology, including the
   Optical Transport Networks (OTN). As a part of the transport network,
   OTN can provide hard pipes with guaranteed data isolation and
   deterministic low latency, which are highly demanded in the Service
   Level Agreement (SLA).

   This document describes a framework for OTN network slicing and a
   YANG data model augmentation of the OTN topology model. Additional
   YANG data model augmentations will be defined in a future version of
   this draft.

2. Use Cases for OTN Network Slicing

2.1. Leased Line Services with OTN

   For end business customers (like OTT or enterprises), leased lines
   have the advantage of providing high-speed connections with low
   costs. On the other hand, the traffic control of leased lines is very
   challenging due to rapid changes in service demands. Carriers are
   recommended to provide network-level slicing capabilities to meet
   this demand. Based on such capabilities, private network users have
   full control over the sliced resources which have allocated to them
   and which could be used to support their leased lines, when needed.
   Users may formulate policies based on the demand for services and
   time to schedule the resources from the entire network's perspective
   flexibly. For example, the bandwidth between any two points may be
   established or released based on the time or monitored traffic
   characteristics. The routing and bandwidth may be adjusted at a
   specific time interval to maximize network resource utilization
   efficiency.

2.2. Co-construction and Sharing

   Co-construction and sharing of a network are becoming a popular means
   among service providers to reduce networking building CAPEX. For Co-
   construction and sharing case, there are typically multiple co-
   founders for the same network. For example, one founder may provide
   optical fibres and another founder may provide OTN equipment, while
   each occupies a certain percentage of the usage rights of the network
   resources. In this scenario, the network O&M is performed by a
   certain founder in each region, where the same founder usually
   deploys an independent management and control system. The other
   founders of the network use each other's management and control



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   system to provision services remotely. In this scenario, different
   founders' network resources need to be automatically (associated)
   divided, isolated, and visualized. In addition, all founders have
   independent O&M capabilities, and should be able to perform service-
   level provisioning in their respective slices.

2.3. Wholesale of optical resources

   In the optical resource wholesale market, smaller, local carriers and
   wireless carriers may rent resources from larger carriers, or
   infrastructure carriers instead of building their networks. Likewise,
   international carriers may rent resources from respective local
   carriers and local carriers may lease their owned networks to each
   other to achieve better network utilization efficiency.

   From the perspective of a resource provider, it is crucial that a
   network slice is timely configured to meet traffic matrix
   requirements requested by its tenants. The support for multi-tenancy
   within the resource provider's network demands that the network
   slices are qualitatively isolated from each other to meet the
   requirements for transparency, non-interference, and security.

   Typically, a resource purchaser expects to use the leased network
   resources flexibly, just like they are self-constructed. Therefore,
   the purchaser is not only provided with a network slice, but also the
   full set of functionalities for operating and maintaining the network
   slice.  The purchaser also expects to, in a flexible and independent
   manner, schedule and maintain physical resources to support their own
   end-to-end automation using both leased and self-constructed network
   resources.

2.4. Vertical dedicated network with OTN

   Vertical industry slicing is an emerging category of network slicing
   due to the high demand for private high-speed network interconnects
   for industrial applications.

   In this scenario, the biggest challenge is to implement
   differentiated optical network slices based on the requirements from
   different industries. For example, in the financial industry, to
   support high-frequency transactions, the slice must ensure to provide
   the minimum latency along with the mechanism for latency management.
   For the healthcare industry, online diagnosis network and software
   capabilities to ensure the delivery of HD video without frame loss.
   For bulk data migration in data centers, the network needs to support
   on-demand, large-bandwidth allocation. In each of the aforementioned



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   vertical industry scenarios, the bandwidth shall be adjusted as
   required to ensure flexible and efficient network resource usage.

3. Framework for OTN slicing

   An OTN slice is a collection of OTN network resources that are used
   to establish a logically dedicated OTN virtual network over one or
   more OTN networks. For example, the bandwidth of an OTN slice is
   described in terms of the number/type of OTN time slots; the labels
   may be specified as OTN tributary slots and/or tributary ports to
   allow slice users to interconnect devices with matching
   specifications.

   The relationship between an OTN slice and an IETF network slice [I-D.
   teas-transport-network-slice-yang] is for further discussions.

   To support the configuration of OTN slices, an OTN slice controller
   (OTN-SC) can be deployed either outside or within the SDN controller.

   In the former case, the OTN-SC translates an OTN slice configuration
   request into a TE topology configuration or a set of TE tunnel
   configurations, and instantiate it by using the TE topology [RFC8795]
   or TE tunnel [I-D.ietf-teas-yang-te] interfaces at the MPI (MDSC-to-
   PNC Interface), as defined in the ACTN framework [RFC8453].

   In the latter case, an Orchestrator or an end-to-end slice controller
   may request OTN slices directly through the OTN slicing interface
   provided by the OTN-SC. A higher-level OTN-SC may also designate the
   creation of OTN slices to a lower-level OTN-SC in a recursive manner.

   Figure 1 illustrates the OTN slicing control hierarchy and the
   positioning of the OTN slicing interfaces.

















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                      +--------------------+
                      | Provider's User    |
                      +--------|-----------+
                               |CMI
        +----------------------+---------------------------+
        |         Orchestrator / E2E Slice Controller      |
        +-----------+------------------------------+-------+
                    |OTN-SC NBI                    |
                    |                              |
        +-----------+---------+   OTN-SC NBI       |OTN-SC NBI
        |      OTN-SC         +---------------+    |
        +-----------+---------+               |    |
                    |MPI                      |    |
       +------------|-------------------------|----|--------+
       | SDN        |                 +-------+----+-------+|
       | Controller |                 |      OTN-SC        ||
       |            |                 +-------+------------+|
       |            |                         |Internal API |
       |+-----------+-------------------------+------------+|
      ||                PNC/MDSC                          ||
       |+-----------------------+--------------------------+|
       +------------------------|---------------------------+
                                |SBI
                    +-----------+----------+
                    |OTN Physical Network  |
                    +----------------------+

             Figure 1 - Positioning of OTN Slicing Interfaces

   A particular OTN network resource, such as a port or link, may be
   sliced in two modes:

   o  Link-based slicing, where a link and its associated link
      termination points (LTPs) are dedicatedly allocated to a
      particular OTN network slice.

   o  Tributary-slot based slicing, where multiple OTN network slices
      share the same link by allocating different OTN tributary slots in
      different granularities.

   Additionally, since OTN tributary slots are usually switched
   unconstrained at every node within an OTN network, it is unimportant
   to which exact tributary slot(s) an OTN slice is allocated, but
   rather mattered is the number and type of the tributary slots.





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4. YANG Data Model for OTN Slicing Configuration

4.1. OTN Slicing YANG Model for MPI

4.1.1. MPI YANG Model Overview

   An SDN controller (PNC or MDSC) exposes to the OTN-SC set of
   available resources for OTN slicing in the form of an abstract TE
   topology. When the OTN-SC receives slice configuration from the NBI,
   it translates the configuration into a coloring scheme on the
   abstract TE topology, by marking corresponding link resources on the
   TE topology received from the SDN controller with a slice identifier
   and OTN-specific resource requirements, e.g. the number of ODU time
   slots. When the SDN controller receives the slice configuration, it
   shall create a new virtual TE link for each of the colored links to
   hold the reserved OTN time slots for time slot-based slicing. These
   resultant virtual links are then included in the TE topology
   advertisement to the OTN-SC.

4.1.2. MPI YANG Model Tree

   module: ietf-otn-slice
     augment /nw:networks/nw:network/nt:link/tet:te/tet:te-link-
   attributes:
       +--rw (otn-slice-granularity)?
          +--:(link)
          |  +--rw slice-id?   uint32
          +--:(link-resource)
             +--rw slices* [slice-id]
                +--rw slice-id            uint32
                +--rw (technology)?
                |  +--:(otn)
                |     +--rw otn-ts-num?   uint32
                +--ro sliced-link-ref?    ->
   ../../../../../nt:link/link-id

                Figure 2 - OTN network slicing tree diagram

4.1.3. MPI YANG Code

   <CODE BEGINS>file "ietf-otn-slice@2021-02-22.yang"
   module ietf-otn-slice {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:ietf-otn-slice";


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     prefix "otnslice";

     import ietf-network {
       prefix "nw";
       reference "RFC 8345: A YANG Data Model for Network Topologies";
     }

     import ietf-network-topology {
       prefix "nt";
       reference "RFC 8345: A YANG Data Model for Network Topologies";
     }

     import ietf-te-topology {
       prefix "tet";
       reference
         "RFC8795: YANG Data Model for Traffic Engineering
         (TE) Topologies";
     }

     import ietf-otn-topology {
       prefix "otntopo";
       reference
         "I-D.ietf-ccamp-otn-topo-yang: A YANG Data Model
          for Optical Transport Network Topology";
     }

     organization
       "IETF CCAMP Working Group";
     contact
       "WG Web: <http://tools.ietf.org/wg/ccamp/>
        WG List: <mailto:ccamp@ietf.org>

        Editor: Haomian Zheng
                <mailto:zhenghaomian@huawei.com>

        Editor: Italo Busi
                <mailto:italo.busi@huawei.com>

        Editor: Aihua Guo
                <mailto:aihuaguo.ietf@gmail.com>



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        Editor: Victor Lopez
                <mailto:victor.lopezalvarez@telefonica.com>";

     description
       "This module defines a YANG data model to configure an OTN
        network slice realization.

        The model fully conforms to the Network Management Datastore
        Architecture (NMDA).

        Copyright (c) 2021 IETF Trust and the persons
        identified as authors of the code.  All rights reserved.

        Redistribution and use in source and binary forms, with or
        without modification, is permitted pursuant to, and subject
        to the license terms contained in, the Simplified BSD License
        set forth in Section 4.c of the IETF Trust's Legal Provisions
        Relating to IETF Documents
        (https://trustee.ietf.org/license-info).
        This version of this YANG module is part of RFC XXXX; see
        the RFC itself for full legal notices.";

     revision "2021-02-22" {
       description
         "Initial Version";
       reference
         "draft-zheng-ccamp-yang-otn-slicing-01: Framework and Data
          Model for OTN Network Slicing";
     }

     /*
      * Groupings
      */

     grouping otn-link-slice-profile {
       choice otn-slice-granularity {
         default link;
         case link {
           leaf slice-id {
             type uint32;
              description


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                "Slice identifier";
           }
         }
         case link-resource {
           list slices {
             key slice-id;
             description
               "List of slices.";
             leaf slice-id {
               type uint32;
                 description
                 "Slice identifier";
             }
             choice technology {
               case otn {
                 leaf otn-ts-num {
                   type uint32;
                   description
                     "Number of OTN tributary slots allocated for the
                      slice.";
                 }
               }
             }
             leaf sliced-link-ref {
               config false;
               type leafref {
                 path "../../../../../nt:link/nt:link-id";
               }
               description
                 "Relative reference to virtual links generated from
                  this TE link.";
             }
           }
         }
       }
     }

     /*
      * Augments
      */



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     augment "/nw:networks/nw:network/nt:link/tet:te/"
           + "tet:te-link-attributes" {
       when "../../../nw:network-types/tet:te-topology/"
          + "otntopo:otn-topology" {
         description
           "Augmentation parameters apply only for networks with
            OTN topology type.";
       }
       description
         "Augment OTN TE link attributes with slicing profile.";
       uses otn-link-slice-profile;
     }
   }
   <CODE ENDS>

                 Figure 3 - OTN network slicing YANG model

4.2. OTN Slicing YANG Model for OTN-SC NBI

   TBD.

5. Manageability Considerations

   To ensure the security and controllability of physical resource
   isolation, slice-based independent operation and management are
   required to achieve management isolation.

   Each optical slice typically requires dedicated accounts,
   permissions, and resources for independent access and O&M. This
   mechanism is to guarantee the information isolation among slice
   tenants and to avoid resource conflicts. The access to slice
   management functions will only be permitted after successful security
   checks.

6. Security Considerations

   <Add any security considerations>

7. IANA Considerations

   <Add any IANA considerations>






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8. References

8.1. Normative References

   [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>.

   [RFC8795] Liu, X., Bryskin, I., Beeram, V., Saad, T., Shah, H., and
             O. Gonzalez de Dios, "YANG Data Model for Traffic
             Engineering (TE) Topologies", RFC 8795, DOI
             10.17487/RFC8795, August 2020, <https://www.rfc-
             editor.org/info/rfc8795>.

   [I-D. teas-transport-network-slice-yang] Liu, X., Tantsura J.,
             Bryskin I., Contreras L., Wu Q., Belotti S., and Rokui R.,
             "Transport Network Slice YANG Data Model", draft-liu-teas-
             transport-network-slice-yang-01 (work in progress), July
             2020.

   [I-D.ietf-teas-yang-te] Saad, T., Gandhi, R., Liu, X., Beeram, V.,
             and I. Bryskin, "A YANG Data Model for Traffic Engineering
             Tunnels and Interfaces", draft-ietf-teas-yang-te-22 (work
             in progress), November 2019.

8.2. Informative References

   TBD

Acknowledgments

   This document was prepared using 2-Word-v2.0.template.dot.

Contributors' Addresses

   Henry Yu
   Huawei Technologies Canada

   Email: henry.yu@huawei.com









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Authors' Addresses

   Haomian Zheng
   Huawei Technologies
   H1, Xiliu Beipo Village, Songshan Lake,
   Dongguan,
   China

   Email: zhenghaomian@huawei.com


   Italo Busi
   Huawei Technologies

   Email: italo.busi@huawei.com


   Aihua Guo
   Futurewei Technologies

   Email: aihuaguo.ietf@gmail.com


   Victor Lopez
   Telefonica I+D/GCTO
   Distrito Telefonica
   E-28050 Madrid, Spain

   Email: victor.lopezalvarez@telefonica.com




















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