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Versions: 00 01                                                         
Network Working Group                                            X. Geng
Internet-Draft                                                     Z. Hu
Intended status: Experimental                                     Huawei
Expires: October 16, 2021                                 April 14, 2021


                      YANG Model for Scalable VTN
           draft-geng-teas-enhanced-vpn-scalable-vtn-yang-00

Abstract

   This document defines the Yang data model for scalable Virtual
   Transport Network(VTN).

Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].

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 October 16, 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
   (https://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



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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.  VTN Yang Module Requirement . . . . . . . . . . . . . . . . .   3
     2.1.  VTN Creation  . . . . . . . . . . . . . . . . . . . . . .   3
     2.2.  VTN Initiation  . . . . . . . . . . . . . . . . . . . . .   4
     2.3.  VTN Traffic Steering  . . . . . . . . . . . . . . . . . .   4
   3.  VTN Yang Module Tree  . . . . . . . . . . . . . . . . . . . .   5
   4.  VTN Yang Module . . . . . . . . . . . . . . . . . . . . . . .   6
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  10
   6.  Contributor . . . . . . . . . . . . . . . . . . . . . . . . .  10
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  10
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .  11
     7.2.  Informative References  . . . . . . . . . . . . . . . . .  12
   Appendix A.  An Appendix  . . . . . . . . . . . . . . . . . . . .  12
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  12

1.  Introduction

   [I-D.ietf-teas-ietf-network-slice-definition] defines IETF network
   slices that provide connectivity coupled with network resources
   commitment between a number of endpoints over a shared network
   infrastructure.

   Enhanced VPN (VPN+) aims to provide enhancements to existing VPN
   services to support network slicing.  VPN+ is composed of a VPN
   overlay and an underlying Virtual Transport Network (VTN) which has a
   customized network topology and a set of dedicated or shared
   resources in the underlay network.  VPN+ and VTN are defined in
   [I-D.ietf-teas-enhanced-vpn].

   [I-D.dong-teas-enhanced-vpn-vtn-scalability] describes the
   scalability considerations in the control plane and data plane to
   enable VPN+ services.  In control plane, decoupling the topology and
   resource attributes of VTN allows that multiple VTNs share the same
   topology.  In data plane, a global VTN-ID in the data packet is used
   to determine the set of resources reserved for the corresponding VTN.

   This document defines the configuration yang model for scalable VTN
   solution.







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2.  VTN Yang Module Requirement

   The general process of VTN configuration includes:

   1.  Creat VTN instance based on the network slice requirement

   2.  Configure the overlay network to initiate VTN in the network

   3.  Steer the traffic to the corresponding VTN to provide network
       slice service

   The corresponding requirement of VTN configuration data model during
   the process is defined in this section.

2.1.  VTN Creation

   After collecting information about the underlying network topology
   and available resources.  Each VTN can have a customized topology and
   a set of network resources allocated.  Flexible combination is
   allowed when multiple VTNs may shared the same topology, or multiple
   VTNs may share the same set of network resources.

   VTN is created with the following attributes:

   o  VTN Topology: Based on the existing work in IETF, topology
      specification for VTN could be implemented by Multi-Topology
      Routing (MTR) which defined in [RFC4915], [RFC5120], or Flex-algo
      which is defined in [I-D.ietf-lsr-flex-algo].  Correspondingly,
      the topology attribute of a VTN could be determined by MT-ID or
      algorithm ID; Signaling extensions for VTN topology is defined in
      [I-D.zhu-lsr-isis-sr-vtn-flexalgo] and
      [I-D.ietf-lsr-isis-sr-vtn-mt] respectively.

   o  Network Resource: network resource is allocated for VTN based on
      the requirement.  For example, VTN could be bound with a layer 2
      sub-interface with a subset of the link bandwidth.

   o  VTN Data Plane Identifier: VTN data plane identifier is uesed to
      identify network resource that has been allocated for the VTN.
      VTN data plane identifier depends on the encapsulation type of the
      traffic, for example IPv6 defined in
      [I-D.dong-6man-enhanced-vpn-vtn-id].  VTN data plane identifier is
      not mandatory when there are other methods to distinguish VTN
      instances.







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2.2.  VTN Initiation

   VTN initiation in the network also includes two aspects: resource
   allocation and traffic steering through VTN specified topology.
   Resource allocation is defined in this section and traffic steering
   is defined in the next section.

   Several technologies could be used for resource allocation in the
   network device, for example: TSN defined in IEEE 802.1 introduces the
   concept of time aware shaping; FlexE provides the ability to
   multiplex multiple channels over one or more Ethernet links; Existing
   Diffserv scheduling/shaping allow the construction of virtual sub-
   interfaces.  All these technologies could be used to dedicated
   resource in a shared physical interface.

   The configuration of these technologies play the role of VTN
   initiation when the allocated resource is bound with a specified VTN
   instance.

2.3.  VTN Traffic Steering

   Just as color in SR policy defined in
   [I-D.ietf-spring-segment-routing-policy], color is defined as an
   attribute of VTN to steer the traffic.

   With SR policy, traffic could be steered into a SR policy by :

   o  SR policy with color is provisioned to the headend;

   o  The route with some particular color matchs the SR policy with the
      corresponding color, which could satisfy the requirement of the
      route

   o  Traffic with the route is steered into the SR policy;

   Similarly, traffic could be steered into VTN by:

   o  VTN is configured with the attribute of color;

   o  The route with some particular color matchs VTN with the
      correponding color, which could satisfy the requirement of the
      route

   o  Traffic with the route is steered to the VTN

   SR policy could also be bound with VTN to provide resource
   reservation in the network.  BGP SR Policy extensions for VTN is
   defined in [I-D.dong-idr-sr-policy-vtn] and similarly, YANG model



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   which is used to bound SR policy to a specified VTN is defined in
   this document by:

   o  SR policy with color is provisioned to the headend; The preferred
      candidate path is bound to VTN;

   o  The route with some particular color matchs the SR policy with the
      corresponding color, which could satisfy the requirement of the
      route

   o  Traffic with the route is steered into the SR policy; Packet is
      encapsulated with the VTN data plane identifier.

3.  VTN Yang Module Tree

   module: ietf-vtn
     +--rw vtn-instance
     |  +--rw vtn-instance* [vtn-id]
     |     +--rw vtn-id                       uint32
     |     +--rw vtn-topology
     |     |  +--rw (vtn-topolgy-type)?
     |     |     +--:(flex-algo)
     |     |     |  +--rw flex-algo
     |     |     |     +--rw flex-algo-id?   uint32
     |     |     +--:(multi-topology)
     |     |        +--rw multi-topology-id?   uint32
     |     +--rw vtn-data-plane-identifier?   uint32
     +--rw sr-policy-extension
        +--rw vtn
           +--rw vtn-id?   uint32

     augment /if:interfaces/if:interface:
       +--rw interface-configuration-for-vtn
          +--rw (vtn-interface-binding-type)?
             +--:(layer-2-sub-interface)
             |  +--rw layer-2-sub-interface
             |     +--rw sub-interface-id?   uint32
             |     +--rw vtn-id?             uint32
             |     +--rw bandwidth?          uint32
             +--:(queue)
                +--rw queue
                   +--rw queue-id?    uint32
                   +--rw vtn-id?      uint32
                   +--rw bandwidth?   uint32
     augment /ni:network-instances/ni:network-instance:
       +--rw vtn-traffic-steering
          +--rw color-index?   uint32
          +--rw vtn-id?        uint32



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4.  VTN Yang Module

module ietf-vtn {
  yang-version 1.1;
  namespace "urn:ietf:params:xml:ns:yang:ietf-vtn";
  prefix "ietf-vtn";

  import ietf-inet-types {
    prefix "inet";
  }

  import ietf-routing {
    prefix "rt";
  }

  import ietf-routing-types {
    prefix "rt-types";
  }

  import ietf-yang-types {
    prefix "yang";
  }

  import ietf-interfaces {
    prefix "if";
  }

  import ietf-network-instance {
    prefix "ni";
  }

  organization "IETF TEAS Working Group";

  contact
    "
         WG Web: <http://tools.ietf.org/wg/teas/>
         WG List:<mailto:teas@ietf.org>

         Editor: Xuesong Geng
                 <mailto:gengxuesong@huawei.com>
     Editor: Zhibo Hu
                 <mailto:huzhibo@huawei.com>
        ";

  description
    "This YANG module defines a data model for VTN(Virtual Transport Network)";

  revision "2021-04-14" {



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    description
      "This is the initial version of VTN yang module";
        reference
          "RFC XXX: YANG Data Model for VTN";
  }

  grouping vtn-instances{
    description
          "VTN instances";
    list vtn-instance {
          key "vtn-id";
      description
        "vtn instance list";
          leaf vtn-id {
            type uint32;
            description
              "vtn-id";
          }
          container vtn-topology {
            description
                  "vtn topology is nt";
                choice vtn-topolgy-type{
                  description
                    "customized topology of VTN";
                  case flex-algo {
                    container flex-algo {
                          description
                            "flex-algo could be used as topology specification for VTN";
                          leaf flex-algo-id {
                            type uint32;
                            description
                              "flex-algo-id for VTN";
                          }
                        }
                  }
                  case multi-topology {
                    description
                          "MT could be used as topology specification for VTN";
                    leaf multi-topology-id{
                          type uint32;
                          description
                            "MT-id for VTN";
                        }
                  }
                }
          }
          leaf vtn-data-plane-identifier {
            type uint32;



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                description
                  "VTN identifier of data plane for vtn distinguishment";
          }
    }
  }

  grouping interface-configuration-for-vtn{
    description
          "interface configuration for vtn";
    container interface-configuration-for-vtn {
          description
            "interface configuration for vtn";
          choice vtn-interface-binding-type{
        description
                  "vtn interface binding type";
                case layer-2-sub-interface {
                  description
                    "vtn is bound to a layer-2 sub-interface";
                  container layer-2-sub-interface {
                    description
                          "sub-interface configuration";
                        leaf sub-interface-id {
                          type uint32;
                          description
                            "sub-interface id";
                        }
                        leaf vtn-id {
                          type uint32;
                          description
                            "vtn-id";
                        }
                        leaf bandwidth {
                          type uint32;
                          description
                            "bandwidth allocation for the slice";
                        }
                  }
                }
                case queue {
                  description
                    "vtn is bound to a queue in the interface";
              container queue {
                    description
                          "queue configuration";
                        leaf queue-id {
                          type uint32;
                          description
                            "queue id";



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                        }
                        leaf vtn-id {
                          type uint32;
                          description
                            "queue id";
                        }
                        leaf bandwidth {
                          type uint32;
                          description
                            "bandwidth allocation for the slice";
                        }
                  }
                }
          }
        }
  }

  grouping sr-policy-traffic-steering{
    container vtn{
          description
            "candidata path is bound to VTN";
          leaf vtn-id{
            type uint32;
                description
                  "vtn";
          }
        }
  }

  grouping vtn-traffic-steering{
    container vtn-traffic-steering {
          leaf color-index {
            type uint32;
                description
                  "color index";
          }
          leaf vtn-id {
            type uint32;
                description
                  "vtn id";
          }
        }
  }

  container vtn-instance {
    description
          "vtn instance configuraiton";
    uses vtn-instances;



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  }

  augment "/if:interfaces/if:interface" {
    description
          "interface model extension for vtn";
        uses interface-configuration-for-vtn;

  }

  augment /ni:network-instances/ni:network-instance{
    description
          "network instance model extension for vtn";
    uses vtn-traffic-steering;
  }

  container sr-policy-extension {
    description
          "sr policy extension for vtn";
        uses sr-policy-traffic-steering;
  }

}

5.  IANA Considerations

   This document makes no request of IANA.

   Note to RFC Editor: this section may be removed on publication as an
   RFC.

6.  Contributor

      Zhenbin Li
      Huawei

      Email: lizhenbin@huawei.com


      Jie Dong
      Huawei

      Email: jie.dong@huawei.com

7.  References







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7.1.  Normative References

   [I-D.dong-6man-enhanced-vpn-vtn-id]
              Dong, J., Li, Z., Xie, C., and C. Ma, "Carrying Virtual
              Transport Network Identifier in IPv6 Extension Header",
              draft-dong-6man-enhanced-vpn-vtn-id-02 (work in progress),
              November 2020.

   [I-D.dong-idr-sr-policy-vtn]
              Dong, J., Hu, Z., and R. Pang, "BGP SR Policy Extensions
              for Virtual Transport Network", draft-dong-idr-sr-policy-
              vtn-00 (work in progress), October 2020.

   [I-D.dong-teas-enhanced-vpn-vtn-scalability]
              Dong, J., Li, Z., Qin, F., and G. Yang, "Scalability
              Considerations for Enhanced VPN (VPN+)", draft-dong-teas-
              enhanced-vpn-vtn-scalability-01 (work in progress),
              November 2020.

   [I-D.ietf-lsr-flex-algo]
              Psenak, P., Hegde, S., Filsfils, C., Talaulikar, K., and
              A. Gulko, "IGP Flexible Algorithm", draft-ietf-lsr-flex-
              algo-13 (work in progress), October 2020.

   [I-D.ietf-lsr-isis-sr-vtn-mt]
              Xie, C., Ma, C., Dong, J., and Z. Li, "Using IS-IS Multi-
              Topology (MT) for Segment Routing based Virtual Transport
              Network", draft-ietf-lsr-isis-sr-vtn-mt-00 (work in
              progress), March 2021.

   [I-D.ietf-spring-segment-routing-policy]
              Filsfils, C., Talaulikar, K., Voyer, D., Bogdanov, A., and
              P. Mattes, "Segment Routing Policy Architecture", draft-
              ietf-spring-segment-routing-policy-09 (work in progress),
              November 2020.

   [I-D.ietf-teas-enhanced-vpn]
              Dong, J., Bryant, S., Li, Z., Miyasaka, T., and Y. Lee, "A
              Framework for Enhanced Virtual Private Networks (VPN+)
              Service", draft-ietf-teas-enhanced-vpn-06 (work in
              progress), July 2020.

   [I-D.ietf-teas-ietf-network-slice-definition]
              Rokui, R., Homma, S., Makhijani, K., Contreras, L., and J.
              Tantsura, "Definition of IETF Network Slices", draft-ietf-
              teas-ietf-network-slice-definition-00 (work in progress),
              January 2021.




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   [I-D.zhu-lsr-isis-sr-vtn-flexalgo]
              Zhu, Y., Dong, J., and Z. Hu, "Using Flex-Algo for Segment
              Routing based VTN", draft-zhu-lsr-isis-sr-vtn-flexalgo-01
              (work in progress), September 2020.

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

   [RFC4915]  Psenak, P., Mirtorabi, S., Roy, A., Nguyen, L., and P.
              Pillay-Esnault, "Multi-Topology (MT) Routing in OSPF",
              RFC 4915, DOI 10.17487/RFC4915, June 2007,
              <https://www.rfc-editor.org/info/rfc4915>.

   [RFC5120]  Przygienda, T., Shen, N., and N. Sheth, "M-ISIS: Multi
              Topology (MT) Routing in Intermediate System to
              Intermediate Systems (IS-ISs)", RFC 5120,
              DOI 10.17487/RFC5120, February 2008,
              <https://www.rfc-editor.org/info/rfc5120>.

7.2.  Informative References

   [InfRef]   , 2004.

Appendix A.  An Appendix

Authors' Addresses

   Xuesong Geng
   Huawei

   Email: gengxuesong@huawei.com


   Zhibo Hu
   Huawei

   Email: huzhibo@huawei.com












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