A Yang Data Model for Transport Slice
draft-wd-teas-transport-slice-yang-00

Abstract

This document provides a YANG data model for the transport slice service. The model can be used by a client management system of the transport slice controller to request, configure, and manage the components of an transport slice service.

The YANG modules in this document conforms to the Network Management Datastore Architecture (NMDA) defined in RFC 8342.

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 September 9, 2020.

Copyright Notice

Copyright (c) 2020 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 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. Conventions used in this document
• 2.1. Tree Diagrams
• 3. Design of the Data Model
• 4. Transport Slice SLO Policy
• 5. Transport Slice Monitoring
• 6. Transport Slice Module
• 7. Security Considerations
• 8. IANA Considerations
• 9. Acknowledgments
• 10. References
• 10.1. Normative References
• 10.2. Informative References
• Appendix A. Appendix A Comparison with Other Possible Transport Slice Models
• Appendix B. Appendix B Transporst Slice Traffic Criteria
• Authors' Addresses

1. Introduction

This document provides a YANG[RFC7950] data model for transport Slice Service.

The YANG model discussed in this document is defined based on the description of the transport slice in[I-D.nsdt-teas-transport-slice-definition] and is used to operate customer-driven transport Slice during the transport Slice Network instantiation, and the operations includes service creation, modification, deletion, and monitoring.

The YANG model discussed in this document suggests an abstract, technology independent model, which includes three major constructs:

• Transport Slice(TS): that describe a logical network that interconnects Transport Slice End Points.
• Ts-Endpoint: is a logical point at an external interface of a Transport slice network, to which a particular subset of traffic that traverse the external interface, and the traffic is mapped to a specific transport slice.
• TS-Member: that describe how each link association between any slice endpoint, it uses to collect the performance data of this unidirectional link.

The YANG models can be used with network management protocols such as NETCONF[RFC6241] or RESTCONF to install, manipulate, and delete the configuration of network devices.

The transport Slice Network operational state is included in the same tree as the configuration consistent with Network Management Datastore Architecture[RFC8342].

2. Conventions used in this document

The keywords "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP14, [RFC2119], [RFC8174] when, and only when, they appear in all capitals, as shown here.

The following terms are defined in [RFC6241] and are used in this specification:

• client
• configuration data
• server
• state data

The following terms are defined in [RFC7950] and are used in this specification: [RFC7950].

• augment
• data model
• data node

The terminology for describing YANG data models is found in

2.1. Tree Diagrams

Tree diagrams used in this document follow the notation defined in [RFC8340].

3. Design of the Data Model

          +----------------------------------------+
          |     A higher level system              |
          |  (e.g. E2E network slice orchestrator) |
          +----------------+-----------------------+
                           |
                           | transport slice YANG
                           |
                           |
     +---------------------+--------------------------+
     |        Transport Slice Controller              |
     +------------------------------------------------+

transport slice yang context

The model presented in this document has the following transport network slicing and ACTN framework context.

In the use case of 5G transport application, E2E network slice orchestrator provides service request to the transport slice controller (i.e., CNC). The interface between the higher level system and transport networks is used to facilitate dynamic transport slice creation and its lifecycle management with proper feedback loop for monitoring.

                 +--------------------------+
                 |                          |
  +-----+  /--\  |                          |  /--\   +-------+
  |     +-+ EP1+-+                          +-+ EP3+--+ Site2 |
  |Site1|  \--/  |                          |  \--/   +-------+
  |     |        |                          |
  |     |  /--\  |                          |  /--\   +-------+
  |     +-+ EP2|-+                          +-+ EP4+--+ Site3 |
  +-----+  \--/  |                          |  \--/   +-------+
                 |        Transport         |
                 |        Network           |
                 +--------------------------+
            |                                    |
            |<-----Transport Slice n------------>|
            |                                    |


      TS-Member 1      EP1-EP2
      TS-Member 2      EP1-EP3
      TS-Member 3      EP2-EP3
      TS-Member 4      EP2-EP4
 Figure 1: An example of TS-Endpoints and TS-Members of a transport slice 

As shown in Figure 1, a Transport Slice(TS) links together End Points at external Interfaces to the sites, which are customer endpoints that request a transport slicing service.

For a particular TS service, a SLO profile needs to be specified. Either a standard profile or a custom profile could be chosen. The "slo-profile" container defines the transport slice SLO policy to be used.

The type of TS topology is required for configuration. The model supports any-to-any, Hub and Spoke (where Hubs can exchange traffic), and the different combinations, which are supported through the order-list of topology. New topologies could be added via augmentation. By default, the any-to-any VPN service topology is used.

In addition, "ep-role" also needs to be defined, which specifies the role of the end point in a particular TS topology. In the any-to-any VPN service topology, all end points MUST have the same role, which will be "any-to-any-role". In the Hub-and-Spoke topology, end points MUST have a Hub role or a Spoke role.

At each external site, one or multiple TS End points could be connect to the Transport Slice. In the example above, when a site is connected to two transport network edge devices in one Transport Slice, two End Points are created.

A site could connect with transport network edge device with the following ways:

• a distinct physical connection
• a logical Layer 2 connection
• An IP tunnel(e.g. using GRE Tunnel)

These connection could be shared with different Transport Slices or be separated for each Transport Slice.

A TS End Point is a logical entity at an external Interface to a customer site. A number of slice specific configuration must be agreed with a customer site and the transport slice, and one TS End Point's attributes may not be same with anotherTS End Point's. The attributes may include some technology specific parameters, such as connections, encapsulation, and routing protocols, etc. This model can be augmented by referring to the parameters of L3SM or L2SM .

At the external Interface, the particular subset of the transport is identified either by a separate interface or by the combination of interface and fields in the packet. The container 'ts-traffic-match' is defined under "endpoint" list to specify the mapping of slice traffic in case of mapping slice traffic by packet fields through interface shared between multiple transport slices.

A TS Member is an abstract entity which represents transport resources mapped to this particular Transport Slice. A TS Member may encompass customer site links, edge points of the PE, intra-domain paths, and inter-domain logical links.

module: ietf-transport-slice
  +--rw transport-slices
     +--rw slice-profiles
     |  +--rw slo-profile* [id]
     |     +--rw id                     string
     |     +--rw profile-description?   string
     +--rw transport-slice* [ts-id]
        +--rw ts-id          uint32
        +--rw ts-name?       string
        +--rw ts-topology*   identityref
        +--rw slo-profile
        |  +--rw (slo-profile)?
        |     +--:(standard)
        |     |  +--rw profile?         leafref
        |     +--:(custom)
        |        +--rw ts-slo-policy
        |           +--rw isolation-type?      identityref
        |           +--rw latency
        |           |  +--rw one-way-latency?   uint32
        |           |  +--rw two-way-latency?   uint32
        |           +--rw jitter
        |           |  +--rw one-way-jitter?   uint32
        |           |  +--rw two-way-jitter?   uint32
        |           +--rw loss
        |           |  +--rw one-way-loss?   decimal64
        |           |  +--rw two-way-loss?   decimal64
        |           +--rw availability-type?   identityref
        +--rw status
        |  +--rw admin-enabled?   boolean
        |  +--ro oper-status?     operational-type
        +--rw ts-endpoint* [ep-id]
        |  +--rw ep-id                     uint32
        |  +--rw ep-name?                  string
        |  +--rw ep-role*                  identityref
        |  +--rw site-access-parameters
        |  |  +--rw site-name?               string
        |  |  +--rw availability-priority?   uint32
        |  +--rw node-id?                  string
        |  +--rw tp-id?                    string
        |  +--rw bandwidth-slo
        |  |  +--rw incoming-bandwidth
        |  |  |  +--rw guaranteed-bandwidth?   te-types:te-bandwidth
        |  |  |  +--rw max-bandwidth?          te-types:te-bandwidth
        |  |  +--rw outgoing-bandwidth
        |  |     +--rw guaranteed-bandwidth?   te-types:te-bandwidth
        |  |     +--rw max-bandwidth?          te-types:te-bandwidth
        |  +--rw mtu                       uint16
        |  +--rw ts-traffic-criteria
        |  |  +--rw vlan?            uint8
        |  |  +--rw dscp?            inet:dscp
        |  |  +--rw src-ip-prefix?   inet:ip-prefix
        |  +--rw status
        |  |  +--rw admin-enabled?   boolean
        |  |  +--ro oper-status?     operational-type
        |  +--ro ep-monitoring
        |     +--ro incoming-utilized-bandwidth?
        |     |       te-types:te-bandwidth
        |     +--ro incoming-bw-utilization        decimal64
        |     +--ro outgoing-utilized-bandwidth?
        |     |       te-types:te-bandwidth
        |     +--ro outgoing-bw-utilization        decimal64
        +--rw ts-member* [ts-member-id]
           +--rw ts-member-id            uint32
           +--rw src
           |  +--rw src-ts-ep-id?   leafref
           +--rw dest
           |  +--rw dest-ts-ep-id?   leafref
           +--rw metric-type?            ts-metric-type
           +--ro ts-member-monitoring
              +--ro latency?   uint32
              +--ro jitter?    uint32
              +--ro loss?      decimal64

4. Transport Slice SLO Policy

Transport slice slo is specified with two parts. One part is per-slice SLO defined in container 'slo-profile', the other part is described in container 'incoming-bandwidth' and container 'outgoing-bandwidth' under 'end-point'.

The Transport Slice common attributes are as follows:

• Isolation: indicates that a transport slice can be enforced as physical resource isolation or logical resource allocations. For physical resource isolation, it implies that the forwarding, policy and address spaces are local with in a transport slice and instantiation of one slice does not conflict with another slice. For logical isolation, only policy and address spaces are isolated from another slice.
• latency: indicates the latency constraint of the slice.
• Jitter: indicates the jitter constraint of the slice.
• Packet loss: indicates reliability constraint.
• Availability: Availability is a probabilistic measure of the length of time that a slice instance functions without a network failure. The availability level will need to be translated into network specific policies such as the protection policy associated with the slice.
• MTU: Specifies the maximum packet length that the slice gurantee to be able to carry across.

The Bandwidth constraint is applied at each End Point of a Transport Slice. The bandwidth container is used to define a guaranteed amount of bandwidth and also a maximum bandwidth for the transport slice.

5. Transport Slice Monitoring

This model also describes performance status of a transport slice. The statistics are described in individual TS link, 'ts-member-monitoring', and an End Point, 'ep-monitoring'.

This model does not define monitoring enabling nodes. The mechanism defined in [RFC8640] and [RFC8641] can be used for either periodic or on-demand subscription.

By specifying subtree filters or xpath filters to 'ts-member' or 'endpoint' ,so that only interested contents will be sent. These two mechanism can be used for monitoring the transport slice performance status so that the client management system could initiate modification based on the transport running status.

6. Transport Slice Module

<CODE BEGINS> file "ietf-transport-slice@2020-03-03.yang"

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

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

  organization
    "IETF Traffic Engineering Architecture and Signaling (TEAS)
     Working Group";
  contact
    "WG Web:  <https://tools.ietf.org/wg/teas/>
     WG List:  <mailto:teas@ietf.org>
     Editor: Bo Wu <lana.wubo@huawei.com>
           : Dhruv Dhody <dhruv.ietf@gmail.com>";
  description
    "This module contains a YANG module for the Transport Slice.";

  revision 2020-03-03 {
    description
      "initial version.";
    reference
      "RFC XXXX: A Yang Data Model for Transport Slice Operation";
  }

  /* Features */
  /* Identities */

  identity ts-topology {
    description
      "Base identity for vpn topology.";
  }

  identity any-to-any {
    base ts-topology;
    description
      "Identity for any-to-any VPN topology.";
  }

  identity hub-spoke {
    base ts-topology;
    description
      "Identity for Hub-and-Spoke VPN topology.";
  }

  identity ep-role {
    description
      "Site Role in a transport slice topology ";
  }

  identity any-to-any-role {
    base ep-role;
    description
      "Site in an any-to-any transport slice.";
  }

  identity hub {
    base ep-role;
    description
      "Hub Role in a Hub-and-Spoke transport slice.";
  }

  identity spoke {
    base ep-role;
    description
      "Spoke Role in a Hub-and-Spoke transport slice.";
  }

  identity isolation-type {
    description
      "Base identity from which specific isolation types are derived.";
  }

  identity physical-isolation {
    base isolation-type;
    description
      "physical isolation.";
  }

  identity logical-isolation {
    base isolation-type;
    description
      "logical-isolation.";
  }

  /*
   * Identity for availability-type
   */

  identity availability-type {
    description
      "Base identity from which specific map types are derived.";
  }

  identity level-1 {
    base availability-type;
    description
      "level 1: 99.9999%";
  }

  identity level-2 {
    base availability-type;
    description
      "level 2: 99.999%";
  }

  identity level-3 {
    base availability-type;
    description
      "level 3: 99.99%";
  }

  identity level-4 {
    base availability-type;
    description
      "level 4: 99.9%";
  }

  identity level-5 {
    base availability-type;
    description
      "level 5: 99%";
  }

  /* typedef */

  typedef operational-type {
    type enumeration {
      enum up {
        value 0;
        description
          "Operational status UP.";
      }
      enum down {
        value 1;
        description
          "Operational status DOWN";
      }
      enum unknown {
        value 2;
        description
          "Operational status UNKNOWN";
      }
    }
    description
      "This is a read-only attribute used to determine the
       status of a particular element";
  }

  typedef ts-metric-type {
    type enumeration {
      enum one-way {
        description
          "represents one-way monitoring type";
      }
      enum two-way {
        description
          "represents two-way monitoring type";
      }
    }
    description
      "enumerated type of monitoring on a ts-member ";
  }

  /* Groupings */

  grouping status-params {
    container status {
      leaf admin-enabled {
        type boolean;
        description
          "Administrative Status UP/DOWN";
      }
      leaf oper-status {
        type operational-type;
        config false;
        description
          "Operations status";
      }
      description
        "";
    }
    description
      "Grouping used to join operational and administrative status
       is re used in the Site Network Acess and in the VPN-Node";
  }

  grouping ts-traffic-classifier {
    container ts-traffic-criteria {
      leaf vlan {
        type uint8 {
          range "0..7";
        }
        description
          "802.1Q matching.";
      }
      leaf dscp {
        type inet:dscp;
        description
          "DSCP value.";
      }
      leaf src-ip-prefix {
        type inet:ip-prefix;
        description
          "Match on IPv4 src or IPv6 src address.";
      }
      description
        "Describes traffic-matching criteria.";
    }
    description
      "Grouping for traffic definition.";
  }

  grouping ep-monitoring-parameters {
    container ep-monitoring {
      leaf incoming-utilized-bandwidth {
        type te-types:te-bandwidth;
        description
          "Bandwidth utilization that represents the actual
           utilization of the incoming endpoint.";
      }
      leaf incoming-bw-utilization {
        type decimal64 {
          fraction-digits 5;
          range "0..100";
        }
        units "percent";
        mandatory true;
        description
          "To be used to define the bandwidth utilization
           as a percentage of the available service bandwidth.";
      }
      leaf outgoing-utilized-bandwidth {
        type te-types:te-bandwidth;
        description
          "Bandwidth utilization that represents the actual
           utilization of the incoming endpoint.";
      }
      leaf outgoing-bw-utilization {
        type decimal64 {
          fraction-digits 5;
          range "0..100";
        }
        units "percent";
        mandatory true;
        description
          "To be used to define the bandwidth utilization
           as a percentage of the available service bandwidth.";
      }
      config false;
      description
        "Grouping for ep-monitoring-parameters.";
    }
  }

  grouping common-monitoring-parameters {
    description
      "Grouping for link-monitoring-parameters.";
    leaf latency {
      type uint32;
      units "usec";
      description
        "The latency statistics per TS member.";
    }
    leaf jitter {
      type uint32 {
        range "0..16777215";
      }
      description
        "The jitter statistics per TS member.";
    }
    leaf loss {
      type decimal64 {
        fraction-digits 6;
        range "0 .. 50.331642";
      }
      description
        "Packet loss as a percentage of the total traffic
         sent over a configurable interval. The finest precision is
         0.000003%. where the maximum 50.331642%.";
      reference
        "RFC 7810, section-4.4";
    }
  }

  grouping endpoint {
    description
      "Transport Slice endpoint related information";
    leaf ep-id {
      type uint32;
      description
        "unique identifier for the referred Transport Slice endpoint";
    }
    leaf ep-name {
      type string;
      description
        "ep name";
    }
    leaf-list ep-role {
      type identityref {
        base ep-role;
      }
      default "any-to-any-role";
      description
        "Role of the endpoint in the Transport Slice.";
    }
    container site-access-parameters {
      leaf site-name {
        type string;
        description
          "The Site that the endpoint is attached with";
      }
      leaf availability-priority {
        type uint32;
        default "100";
        description
          "In multihoming access of one site, the priority for
           this Endpoint is specified . The higher the value, the higher
           the preference of the Endpoint will be.";
      }
      description
        "Site specific parameters.";
    }
    leaf node-id {
      type string;
      description
        "Uniquely identifies an edge node within the transport
         network.";
    }
    leaf tp-id {
      type string;
      description
        "Termination point identifier of an edge node.";
    }
    container bandwidth-slo {
      container incoming-bandwidth {
        leaf guaranteed-bandwidth {
          type te-types:te-bandwidth;
          description
            "If guaranteed-bandwidth is 0, it means best effort, no
             minimum throughput is guaranteed.";
        }
        leaf max-bandwidth {
          type te-types:te-bandwidth;
          description
            "max bandwidth ";
        }
        description
          "Container for the incoming bandwidth policy";
      }
      container outgoing-bandwidth {
        leaf guaranteed-bandwidth {
          type te-types:te-bandwidth;
          description
            "If guaranteed-bandwidth is 0, it means best effort, no
             minimum throughput is guaranteed.";
        }
        leaf max-bandwidth {
          type te-types:te-bandwidth;
          description
            "max bandwidth ";
        }
        description
          "Container for the bandwidth policy";
      }
      description
        "Container for the bandwidth SLO policy";
    }
    leaf mtu {
      type uint16;
      units "bytes";
      mandatory true;
      description
        "MTU at service level. If the service is IP,
         it refers to the IP MTU. If the service is Ethertype,
         will refer to the Ethernet MTU. ";
    }
    uses ts-traffic-classifier;
    uses status-params;
    uses ep-monitoring-parameters;
  }

  //ts-ep

  grouping ts-member {
    description
      "ts-member is described by this container";
    leaf ts-member-id {
      type uint32;
      description
        "ts-member identifier";
    }
    container src {
      description
        "the source of TS link";
      leaf src-ts-ep-id {
        type leafref {
          path "/transport-slices/transport-slice/ts-endpoint/ep-id";
        }
        description
          "reference to source TS endpoint";
      }
    }
    container dest {
      description
        "the destination of TS link ";
      leaf dest-ts-ep-id {
        type leafref {
          path "/transport-slices/transport-slice/ts-endpoint/ep-id";
        }
        description
          "reference to dest TS endpoint";
      }
    }
    leaf metric-type {
      type ts-metric-type;
      description
        "One way or two way monitoring type.";
    }
    container ts-member-monitoring {
      description
        "SLO status Per ts endpoint to endpoint ";
      config false;
      uses common-monitoring-parameters;
    }
  }

  //ts-member

  grouping transport-slice-slo-policy {
    description
      "policy for transport-slice-slo-level";
    container slo-profile {
      description
        "SLO profile.";
      choice slo-profile {
        description
          "Choice for SLO profile.
           Can be standard profile or customized profile.";
        case standard {
          description
            "Standard SLO profile.";
          leaf profile {
            type leafref {
              path "/transport-slices/slice-profiles/slo-profile/id";
            }
            description
              "QoS profile to be used.";
          }
        }
        case custom {
          description
            "Customized SLO profile.";
          container ts-slo-policy {
            leaf isolation-type {
              type identityref {
                base isolation-type;
              }
              default "logical-isolation";
              description
                "TS service isolation-level.";
            }
            container latency {
              leaf one-way-latency {
                type uint32 {
                  range "0..16777215";
                }
                units "usec";
                description
                  "lowest latency in micro seconds.";
              }
              leaf two-way-latency {
                type uint32 {
                  range "0..16777215";
                }
                description
                  "lowest-way delay or latency in micro seconds.";
              }
              description
                "Latency constraint on the traffic class.";
            }
            container jitter {
              leaf one-way-jitter {
                type uint32 {
                  range "0..16777215";
                }
                description
                  "lowest  latency in micro seconds.";
              }
              leaf two-way-jitter {
                type uint32 {
                  range "0..16777215";
                }
                description
                  "lowest-way delay or latency in micro seconds.";
              }
              description
                "Jitter constraint on the traffic class.";
            }
            container loss {
              leaf one-way-loss {
                type decimal64 {
                  fraction-digits 6;
                  range "0 .. 50.331642";
                }
                description
                  "Packet loss as a percentage of the total traffic
                   sent over a configurable interval. The finest precision is
                   0.000003%. where the maximum 50.331642%.";
                reference
                  "RFC 7810, section-4.4";
              }
              leaf two-way-loss {
                type decimal64 {
                  fraction-digits 6;
                  range "0 .. 50.331642";
                }
                description
                  "Packet loss as a percentage of the total traffic
                   sent over a configurable interval. The finest precision is
                   0.000003%. where the maximum 50.331642%.";
                reference
                  "RFC 7810, section-4.4";
              }
              description
                "Loss constraint on the traffic class.";
            }
            leaf availability-type {
              type identityref {
                base availability-type;
              }
              description
                "Availability Requirement for the Service";
            }
            description
              "container for customized policy constraint on the slice traffic.";
          }
        }
      }
    }
  }

  grouping slice-profile {
    container slice-profiles {
      list slo-profile {
        key "id";
        leaf id {
          type string;
          description
            "Identification of the SLO Profile to be used.
             Local administration meaning.";
        }
        leaf profile-description {
          type string;
          description
            "Description of the SLO Profile.";
        }
        description
          "List for SLO Profile Identifiers.";
      }
      description
        "Container for slice-profiles.";
    }
    description
      "Grouping for slice-profiles.";
  }

  /* Configuration data nodes */

  container transport-slices {
    description
      "transport-slice configurations";
    uses slice-profile;
    list transport-slice {
      key "ts-id";
      description
        "a transport-slice is identified by a ts-id";
      leaf ts-id {
        type uint32;
        description
          "a unique transport-slice identifier";
      }
      leaf ts-name {
        type string;
        description
          "ts name";
      }
      leaf-list ts-topology {
        type identityref {
          base ts-topology;
        }
        default "any-to-any";
        description
          "TS service topology.";
      }
      uses transport-slice-slo-policy;
      uses status-params;
      list ts-endpoint {
        key "ep-id";
        uses endpoint;
        description
          "list of endpoints in this slice";
      }
      list ts-member {
        key "ts-member-id";
        description
          "List of ts-member in a slice";
        uses ts-member;
      }
    }
    //ts-list
  }
}
  

<CODE ENDS>

7. Security Considerations

The YANG module defined in this document is designed to be accessed via network management protocols such as NETCONF [RFC6241] or RESTCONF [RFC8040]. The lowest NETCONF layer is the secure transport layer, and the mandatory-to-implement secure transport is Secure Shell (SSH) [RFC6242]. The lowest RESTCONF layer is HTTPS, and the mandatory-to-implement secure transport is TLS [RFC8446].

The NETCONF access control model [RFC8341] provides the means to restrict access for particular NETCONF or RESTCONF users to a preconfigured subset of all available NETCONF or RESTCONF protocol operations and content.

There are a number of data nodes defined in this YANG module that are writable/creatable/deletable (i.e., config true, which is the default). These data nodes may be considered sensitive or vulnerable in some network environments. Write operations (e.g., edit-config) to these data nodes without proper protection can have a negative effect on network operations.

o /ietf-transport-slice/transport-slices/transport-slice

The entries in the list above include the whole transport network configurations corresponding with the slice which the higher management system requests, and indirectly create or modify the PE or P device configurations. Unexpected changes to these entries could lead to service disruption and/or network misbehavior.

8. IANA Considerations

This document registers a URI in the IETF XML registry [RFC3688]. Following the format in [RFC3688], the following registration is requested to be made:

   URI: urn:ietf:params:xml:ns:yang:ietf-transport-slice
   Registrant Contact: The IESG.
   XML: N/A, the requested URI is an XML namespace.

This document requests to register a YANG module in the YANG Module Names registry [RFC7950].

           Name: ietf-transport-slice
           Namespace: urn:ietf:params:xml:ns:yang:ietf-transport-slice
           Prefix: ts
           Reference: RFC XXXX 

9. Acknowledgments

The authors wish to thank Qin Wu, and many others for their helpful comments and suggestions.

10. References

10.1. Normative References

10.2. Informative References

Appendix A. Appendix A Comparison with Other Possible Transport Slice Models

1.Transport Slice model based on IETF ACTN VN model

The ACTN VN(Virtual Network) model introduced in[I-D.ietf-teas-actn-vn-yang]

is the abstract customer view of the TE network. Its YANG structure includes four components: .

• VN: The VN can be seen as a set of edge-to-edge abstract links (a Type 1 VN).
• AP"links" list and "termination points" list describe how nodes in a network are connected to each other
• VN-AP:vertical layering relationships between transport slice networks and underlay networks
• VN member: Each abstract link is referred to as a VN member and is formed as an E2E tunnel across the underlying networks

The main concern with this model is TE specific, which does not comply with the technology agnostic characteristic specified in [I-D.nsdt-teas-transport-slice-definition].

2.Transport Slice model based on IETF Network Topologies YANG data model extension

IETF Network Topologies YANG data model extension introduced in Transport Network Slice YANG Data Modelhas the similar goal, but with different modelling design. Its YANG structure includes three parts:

• Transport network: a transport network list and an list of nodes contained in the transport network
• Link: "links" list and "termination points" list describe how nodes in a network are connected to each other
• Support network: vertical layering relationships between transport slice networks and underlay networks

Based on this structure, the transport slice-specific SLO attributes nodes are augmented on the Network Topologies model,, e.g. isolation etc. However, this modeling design requires the transport network to expose a lot of details of the network, such as the actual topology including nodes interconnection and different network layers interconnection.

Appendix B. Appendix B Transporst Slice Traffic Criteria

In some scenarios, some sites supports the customer service traffic of multiple slices. The transport network connected to the sites needs to identify the traffic of' different slices to provide different SLO guarantees. But the transport network does not have prior knowledge of these information. Therefore, the transport slice model needs to carry these slice traffic classification information. 'ts-traffic-criteria' container is used to specify the TS traffic-related parameters, including IP addresses, VLAN information, and etc.

    +-------------------------------------------------------+
    |            Higher Layer  System                       |
    +-------------------------------------------------------+
      |                       |                         |
      |             Transport Slice Model               |
 +----------+                 |                   +-----------+
 |          |                 |                   |           |
 |RAN Slice |         +----------------+          |Core Slice |
 |controlle |         | TS  controller |          | controller|
 +----+-----+         +-------+--------+          +-----+-----+
      |                       |                         |
      |                       |                         |
  +---+--+       +------------+----------------+       ++-----+
  |      |       |                             |       |      |
  |      |       |                             |       |      |
  |+----+|TS1-EP1|                             |       |      |
  ||    ||   |   |         TS1                 |       |+----+|
  ||gNB1|+---+---+-----+-----------------------+---+---+|UPF1||
  ||    |+***+******  /                        |   |   |+----+|
  |+----+|TS2-EP1|  */                         |TS1-EP3|      |
  |      |       |  /*                         |       |      |
  |+----+|TS1-EP2| /  *                        |       |      |
  ||    |+---+----     *    TS2                |       |+----+|
  ||gNB2|+***+*************************************+****|UPF2||
  ||    ||   |   |                             |   |   |+----+|
  |+----+|TS2-EP2|                             |TS2-EP3|      |
  |      |       |                             |       |      |
  |      |       |                             |       |      |
  +------+       +-----------------------------+       +------+

As shown in the figure, gNodeB 1 and gNodeB 2 use IP gNB1 and IP gNB2 to communicate with the transport network, respectively. In addition, the traffic of TS1 and TS2 on gNodeB 1 and gNodeB 2 is transmitted through the same links to the transport network. Therefore, edge devices of the transport network cannot use IP addresses to distinguish a specific slice traffic. Other information is therefore needed to identity it.

Authors' Addresses