Internet-Draft TVR Schedule YANG October 2023
Qu, et al. Expires 13 April 2024 [Page]
Workgroup:
Internet
Published:
Intended Status:
Standards Track
Expires:
Authors:
Y. Qu
Futurewei
A. Lindem
LabN Consulting, L.L.C.
E. Kinzie
LabN Consulting, L.L.C.
D. Fedyk
LabN Consulting, L.L.C.
M. Blanchet
Viagenie

YANG Data Model for Scheduled Attributes

Abstract

The YANG model in this document includes three modules, and can be used to manage network resources and topologies with scheduled attributes, such as predictable link loss and link connectivity as a function of time. The intent is to have this information be utilized by Time-Variant Routing systems.

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 13 April 2024.

Table of Contents

1. Overview

YANG [RFC7950] is a data definition language used to define the contents of a conceptual data store that allows networked devices to be managed using NETCONF [RFC6241]. YANG is proving relevant beyond its initial confines, as bindings to other interfaces (e.g., ReST) and encodings other than XML (e.g., JSON) are being defined. Furthermore, YANG data models can be used as the basis for implementation of other interfaces, such as CLI and programmatic APIs.

In some network scenarios, it's possible to predict the times at which one router will be able to establish a link with another router. Links can be predictably lost and re-established, and neighbors may change as a function of time. For examples of such networks and scenarios, please reference TVR (Time-Variant Routing) Use Cases [I-D.ietf-tvr-use-cases].

The YANG model in this document can be used to manage network resources and topologies with scheduled attributes. There are three YANG modules in this document.

Module ietf-tvr-schedule.yang contains the schedule YANG definitions. Module ietf-tvr-topology.yang defines a network topology with time-variant availability. Module ietf-tvr-node.yang is to be used to manage scheduled attributes of a single node.

The YANG modules in this document conform to the Network Management Datastore Architecture (NMDA) [RFC8342].

1.1. 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 [RFC2119] [RFC8174].

2. Tree Diagrams

This document uses the graphical representation of data models defined in [RFC8340].

3. Design of the model

3.1. Schedule Definitions

Module ietf-tvr-schedule.yang contains schedule definitions that can be used by other modules.

The grouping "schedule" is defined in this module, which can be used by other models to define time variant attributes.

The grouping "schedule-lifetime" is to define the lifetime of a "schedule". It has a "schedule-start-time" using "date-and-time", and the "schedule-end-time" can be an option of infinite, duration or date time. If the "schedule-start-time" is set to a time in the past when a configuration is done, the schedule is effective right away.

A schedule may have a repetition pattern and the leaf "recurrence" defines the duration of the repetition pattern of in the "base-schedule", such as daily or weekly. The "base-schedule", which is the basic unit of this schedule, consists a list of "intervals". These intervals specify the attribute values during the "base-schedule". The "recurrence" defines the duration of each "base-schedule", so the configured "intervals" should be within this duration. For example, if the "recurrence" is configured as daily, the last "end-time" in the list should not be larger than 24 hours, which is 8640000 in timeticks. Also each "end-time" must be greater than the "start-time" in the same interval. The "timeticks" defined in [RFC6991] is used to specify the relative "start-time" and "end-time" in each recurrence.

No leaf is provided for values in the schedule. The base-schedule can, if necessary, be augmented in the YANG "uses" clause to fill in the empty value container with whatever is required to represent the affected data.

When a schedule starts in the middle of an recurrence, for example, the recurrence is set to "daily", and the "schedule-start-time" is 8:00AM, when the schedule starts, the "value" should be the 8:00AM value defined by the "base-schedule".

When an attribute's schedule ends, the "value-default" SHOULD be used, if present.

The following figure provides an illustration of two attributes and their scheduled value changes. The attributes A1 and A2 take on different values at different times. The attribute A1 will take on the value v1 from the time t0 until t1, the value v2 from t1 until t2, and v3 from t2 until t3. The attribute A2 will take on the value vv1 from time t0 until t1 and vv2 from v1 until v3.

Attributes
          +-------------------+----------+------+
      A1  |       v1          |   v2     |  v3  |
          +-------------------+----------+------+
      A2  |      vv1          |      vv2        |
          +-------------------+-----------------+
         t0                  t1        t2      t3
                         Time
Figure 1: Time Varying Properties

The following is the tree diagram of the groupings in ietf-tvr-schedule.yang.

            module: ietf-tvr-schedule

  grouping schedule-lifetime:
    +-- start-date-time?       yang:date-and-time
    +-- (end-time)?
       +--:(infinite)
       |  +-- no-end-time?     empty
       +--:(duration)
       |  +-- duration?        uint32
       +--:(end-date-time)
          +-- end-date-time?   yang:date-and-time
  grouping base-schedule:
    +-- recurrence?      recurrence-type
    +-- value-default
    +-- base-schedule
       +-- intervals* [start-time]
          +-- start-time?   yang:timeticks
          +-- end-time?     yang:timeticks
          +-- value
  grouping schedule:
    +-- start-date-time?       yang:date-and-time
    +-- (end-time)?
    |  +--:(infinite)
    |  |  +-- no-end-time?     empty
    |  +--:(duration)
    |  |  +-- duration?        uint32
    |  +--:(end-date-time)
    |     +-- end-date-time?   yang:date-and-time
    +-- recurrence?            recurrence-type
    +-- value-default
    +-- base-schedule
       +-- intervals* [start-time]
          +-- start-time?   yang:timeticks
          +-- end-time?     yang:timeticks
          +-- value
Figure 2: Tree diagram of TVR Schedule groupings

3.2. TVR Node YANG Module

Module ietf-tvr-node.yang is a device model and designed to manage a single node with scheduled attributes.

Each node has list of interfaces, and each interface has a list of power up and down schedules.

3.3. TVR Topology YANG Module

Module ietf-tvr-topology.yang describes a network topology with a time-variant availability schedule.

The module has a list of nodes, identified by a unique "node-id". Each node has a list of links. Links are modeled as unidirectional. Link availability is described from the viewpoint of a particular source node (the transmitting node) and beginning at a particular time. Each link in the list contains the range of times during which it is available.

The "source-link-id" is a string and used to identify a link as viewed from the source-node. Bandwidth and delay are predicted link attributes. Delay is the link propagation time and does not include any queuing delays.

4. TVR YANG Trees

4.1. TVR Node YANG Tree

The following figure shows the tree diagram of the TVR Node scheduling.

module: ietf-tvr-node
  +--rw node-schedule
     +--rw router-id?            yang:dotted-quad
     +--rw power-schedule* [start-date-time]
     |  +--rw start-date-time        yang:date-and-time
     |  +--rw (end-time)?
     |  |  +--:(infinite)
     |  |  |  +--rw no-end-time?     empty
     |  |  +--:(duration)
     |  |  |  +--rw duration?        uint32
     |  |  +--:(end-date-time)
     |  |     +--rw end-date-time?   yang:date-and-time
     |  +--rw recurrence?            recurrence-type
     |  +--rw value-default
     |  |  +--rw default-power?   boolean
     |  +--rw base-schedule
     |     +--rw intervals* [start-time]
     |        +--rw start-time    yang:timeticks
     |        +--rw end-time?     yang:timeticks
     |        +--rw value
     |           +--rw power?   boolean
     +--rw interface-schedule
        +--rw interfaces* [name]
           +--rw name                string
           +--rw up-down-schedule* [start-date-time]
              +--rw start-date-time        yang:date-and-time
              +--rw (end-time)?
              |  +--:(infinite)
              |  |  +--rw no-end-time?     empty
              |  +--:(duration)
              |  |  +--rw duration?        uint32
              |  +--:(end-date-time)
              |     +--rw end-date-time?   yang:date-and-time
              +--rw recurrence?            recurrence-type
              +--rw value-default
              |  +--rw default-available?   boolean
              +--rw base-schedule
                 +--rw intervals* [start-time]
                    +--rw start-time    yang:timeticks
                    +--rw end-time?     yang:timeticks
                    +--rw value
                       +--rw available?   boolean

4.2. TVR Topology YANG Tree

The following figure shows the tree diagram of the TVR Topology scheduling.

module: ietf-tvr-topology
  +--rw topology-schedule
     +--rw nodes* [node-id]
     |  +--rw node-id      inet:uri
     |  +--rw available* [start-date-time]
     |     +--rw start-date-time        yang:date-and-time
     |     +--rw (end-time)?
     |     |  +--:(infinite)
     |     |  |  +--rw no-end-time?     empty
     |     |  +--:(duration)
     |     |  |  +--rw duration?        uint32
     |     |  +--:(end-date-time)
     |     |     +--rw end-date-time?   yang:date-and-time
     |     +--rw recurrence?            recurrence-type
     |     +--rw value-default
     |     |  +--rw default-node-available?   boolean
     |     +--rw base-schedule
     |        +--rw intervals* [start-time]
     |           +--rw start-time    yang:timeticks
     |           +--rw end-time?     yang:timeticks
     |           +--rw value
     |              +--rw node-available?   boolean
     +--rw links* [source-node source-link-id]
        +--rw source-node         inet:uri
        +--rw destination-node?   inet:uri
        +--rw source-link-id      string
        +--rw available* [start-date-time]
           +--rw start-date-time        yang:date-and-time
           +--rw (end-time)?
           |  +--:(infinite)
           |  |  +--rw no-end-time?     empty
           |  +--:(duration)
           |  |  +--rw duration?        uint32
           |  +--:(end-date-time)
           |     +--rw end-date-time?   yang:date-and-time
           +--rw recurrence?            recurrence-type
           +--rw value-default
           +--rw base-schedule
           |  +--rw intervals* [start-time]
           |     +--rw start-time    yang:timeticks
           |     +--rw end-time?     yang:timeticks
           |     +--rw value
           +--rw bandwidth
           |  +--rw recurrence?      recurrence-type
           |  +--rw value-default
           |  |  +--rw default-bandwidth?   te-types:te-bandwidth
           |  +--rw base-schedule
           |     +--rw intervals* [start-time]
           |        +--rw start-time    yang:timeticks
           |        +--rw end-time?     yang:timeticks
           |        +--rw value
           |           +--rw bandwidth?   te-types:te-bandwidth
           +--rw delay
              +--rw recurrence?      recurrence-type
              +--rw value-default
              |  +--rw default-delay?   uint32
              +--rw base-schedule
                 +--rw intervals* [start-time]
                    +--rw start-time    yang:timeticks
                    +--rw end-time?     yang:timeticks
                    +--rw value
                       +--rw delay?   uint32

5. TVR Schedule YANG Modules

5.1. TVR Schedule YANG Module

<CODE BEGINS> file "ietf-tvr-schedule@2023-10-11.yang"
module ietf-tvr-schedule {
  yang-version 1.1;
  namespace "urn:ietf:params:xml:ns:yang:ietf-tvr-schedule";
  prefix tvr-schd;

  import ietf-yang-types {
    prefix "yang";
    reference
      "RFC 6991: Common YANG Data Types";
  }

  organization
    "IETF TVR - Time Variant Routing Working Group";
  contact
    "WG Web:   <http://datatracker.ietf.org/wg/tvr>
     WG List:  <mailto:tvr@ietf.org>

     Author:   Yingzhen Qu
               <mailto:yingzhen.ietf@gmail.com>
     Author:   Acee Lindem
               <mailto:acee.ietf@gmail.com>
     Author:   Marc Blanchet
               <mailto:marc.blanchet@viagenie.ca>
     Author:   Eric Kinzie
               <mailto:ekinzie@labn.net>
     Author:   Don Fedyk
               <mailto:dfedyk@labn.net>";

  description
    "The YANG module contains common YANG definitions for
     time-variant schedule.

     This YANG model conforms to the Network Management
     Datastore Architecture (NMDA) as described in RFC 8342.

     Copyright (c) 2023 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 Revised 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
     (https://www.rfc-editor.org/info/rfcXXXX); see the RFC itself
     for full legal notices.

     The key words '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 BCP 14 (RFC 2119) (RFC 8174) when, and only when,
     they appear in all capitals, as shown here.";
  reference
    "RFC XXXX: YANG Data Model for Scheduled Attributes";

  revision 2023-10-11 {
    description
      "Initial Version";
    reference
      "RFC XXXX: YANG Data Model for Scheduled Attributes.";
  }

  typedef recurrence-type {
    type enumeration {
      enum once {
        description
           "Repeat the scheduled action or attribute modificaton
           only once";
      }
      enum hourly {
        description
          "Repeat the scheduled action or attribute modificaiton
          once per hour.";
      }
      enum daily {
        description
          "Repeat the scheduled action or attribute modificaiton
           once per day.";
      }
      enum weekly {
        description
          "Repeat the scheduled action or attribute modificaiton
           once per week.";
      }
      enum monthly {
        description
          "Repeat the scheduled action or attribute modificaiton
           once per week.";
      }
      enum yearly {
        description
          "Repeat the scheduled action or attribute modificaiton
           once per year.";
      }
    }
    description
      "Types of recurrence";
  }

  grouping schedule-lifetime {
    description
      "Schedule lifetime specification.";
    leaf start-date-time {
      type yang:date-and-time;
      description
        "Start time of the schedule.";
    }
    choice end-time {
      default "infinite";
      description
        "End-time setting.";
      case infinite {
        leaf no-end-time {
          type empty;
          description
            "Indicates schedule lifetime end-time is infinite.";
        }
      }
      case duration {
        leaf duration {
          type uint32 {
            range "1..2147483646";
          }
          units "seconds";
          description
            "Schedule lifetime duration, in seconds";
        }
      }
      case end-date-time {
        leaf end-date-time {
          type yang:date-and-time;
          description
            "End time.";
        }
      }
    }
  }

  grouping base-schedule {
    leaf recurrence {
      type recurrence-type;
      default "once";
      description
        "Type of recurrence";
    }

    container value-default {
      description
        "Attributes default values. This container should be
        augmented with one or more leafs, each of which is used
        when the value is not covered by a base-schedule interval,
        as well as when the schedule ends.";
    }

    container base-schedule {
      list intervals {
        key "start-time";
        leaf start-time {
          type yang:timeticks;
          must "((../../../recurrence != 'hourly') or "
            +      "(current() < 360000)) and "
            +  "((../../../recurrence != 'daily') or "
            +      "(current() < 8640000)) and "
            +  "((../../../recurrence != 'monthly') or "
            +      "(current() < 267840000)) and "
            +   "((../../../recurrence != 'yearly') or "
            +      "(current() < 3162240000))"  {
            error-message
              "The start-time must not exceed the recurrence
               interval";
            description
              "The start-time must not exceed the recurrrence
               interval. For example, for a 'monthy' recurrence, the
               start-time must not exceed 31 days.";
          }
          description
            "Start time of the scheduled value within one recurrence.
             The calculation of the real start time is to use
             the basestarting time defined by schedule-lifetime,
             recurrence, and the timeticks. For example, if a
             schedule starts at 2001/1/1 8:00AM with an hourly
             recurrence, and the timeticks is 180,000 (30 mins),
             the start-time will be every 30 mins pass an hour
             after 2001/1/1.";
        }
        leaf end-time {
          type yang:timeticks;
          must "(current() > ../start-time) and "
            +  "((../../../recurrence != 'hourly') or "
            +      "(current() < (../start-time + 360000))) and "
            +  "((../../../recurrence != 'daily') or "
            +      "(current() < (../start-time + 8640000))) and "
            +  "((../../../recurrence != 'monthly') or "
            +      "(current() < (../start-time + 267840000))) and "
            +   "((../../../recurrence != 'yearly') or "
            +      "(current() < (../start-time + 3162240000)))"  {
            error-message
              "The end-time must be greater than the end time and
               must not exceed the recurrrence interval.";
            description
              "The end-time must be greater than the end time and
               must not exceed the recurrrence interval. For example,
               for a 'daily' recurrence, the time-tick offset must
               not exceed the start-time + 24 hours.";
          }
          description
            "End time of the scheduled change. The calculation of the
             end-time is the same as the start-time.";
        }
        container value {
          description
           "Attribute value(s). This container should be augmented
           with attributes that apply to the current interval.";
        }
        description
          "List of intervals for action or attribute modification.
           The intervals should be contained within each recurrence.
           For example, when the recurrence is set to daily, the list
           of intervals should be within this daily range, e.g., the
           last end-time can't be larger than 8640000 (24hours).";
      }
      description
        "The recurring base-schedule of the action or attribute
         modification";
    }
    description
      "Grouping definition of base-schedule.";
  }

  grouping schedule {
    uses schedule-lifetime;
    uses base-schedule;
    description
      "Complete schedule for a action or attribute modification.";
  }
}
<CODE ENDS>

5.2. TVR Schedule Node Module

<CODE BEGINS> file "ietf-tvr-node@2023-10-11.yang"
module ietf-tvr-node {
  yang-version 1.1;
  namespace "urn:ietf:params:xml:ns:yang:ietf-tvr-node";
  prefix tvr-node;

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

  import ietf-tvr-schedule {
    prefix "tvr-schd";
  }

  organization
    "IETF TVR - Time Variant Routing Working Group";
  contact
    "WG Web:   <http://datatracker.ietf.org/wg/tvr>
     WG List:  <mailto:tvr@ietf.org>

     Author:   Yingzhen Qu
               <mailto:yingzhen.ietf@gmail.com>
     Author:   Acee Lindem
               <mailto:acee.ietf@gmail.com>
     Author:   Marc Blanchet
               <mailto:marc.blanchet@viagenie.ca>
     Author:   Eric Kinzie
               <mailto:ekinzie@labn.net>
     Author:   Don Fedyk
               <mailto:dfedyk@labn.net>";

  description
    "The YANG module defines a schedule for changing
     attributes of a single node.

     This YANG model conforms to the Network Management
     Datastore Architecture (NMDA) as described in RFC 8342.

     Copyright (c) 2023 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 Revised 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
     (https://www.rfc-editor.org/info/rfcXXXX); see the RFC itself
     for full legal notices.

     The key words '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 BCP 14 (RFC 2119) (RFC 8174) when, and only when,
     they appear in all capitals, as shown here.";
  reference
    "RFC XXXX: YANG Data Model for Scheduled Attributes";

  revision 2023-10-11 {
    description
      "Initial Version";
    reference
      "RFC XXXX: YANG Data Model for Scheduled Attributes.";
  }

  container node-schedule {
    description
      "This container defined time variant attributes
       for node's schedule.";

    leaf router-id {
      type yang:dotted-quad;
      description
        "A 32-bit number used to identify a router.";
    }

    list power-schedule {
      key "start-date-time";
      description
        "Power schedule for the node. The node's power is
         represented by a boolean value with 'true' indicating
         the node is powered on and 'false' indicating the node
         is powered off.";
      uses tvr-schd:schedule {
        augment value-default {
          description
            "Augment the default power state.";
          leaf default-power {
            type boolean;
            default false;
            description
              "This indicates the default node power when for
               time periods when no interval is defined. If
               unspecified, the node is powered down by default.";
          }
        }
        augment base-schedule/intervals/value {
          description
            "Augmment the scheduled power state.";
          leaf power {
            type boolean;
            description
              "Indicates whether the node is powered on.";
          }
        }
      }
    }

    container interface-schedule {
      description
        "Container for TVR node interface attributes.";

      list interfaces {
        key "name";
        description
          "List of interface with schedules.";
        leaf name {
          type string;
          description
            "Name of the interface.
             If used with the ietf-interfaces module, the name should
             match the name of the interface.";
        }

        list up-down-schedule {
          key "start-date-time";
          description
           "Scheduled times that the interface is up. This is to
           work with the leaf 'enabled' for the configured state
           of the interface.";

          uses tvr-schd:schedule {
            augment value-default {
              description
                "Augment default interface state.";
              leaf default-available {
                type boolean;
                default false;
                description
                  "By default, the link is not available.";
              }
            }
            augment base-schedule/intervals/value {
              description
                "Augment scheduled interface state.";
              leaf availble {
                type boolean;
                description
                  "Link availability.";
              }
            }
          }
        }
      }
    }
  }
}
<CODE ENDS>

5.3. TVR Toplogy Module

<CODE BEGINS> file "ietf-tvr-topology@2023-10-11.yang"
module ietf-tvr-topology {
  yang-version 1.1;
  namespace "urn:ietf:params:xml:ns:yang:ietf-tvr-topology";
  prefix tvr-topo;

  import ietf-inet-types {
    prefix inet;
    reference
      "RFC 6991: Common YANG Data Types";
  }

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

  import ietf-tvr-schedule {
    prefix "tvr-schd";
  }

  organization
    "IETF Time-Variant Routing Working Group";

  contact
    "WG Web:   <https://datatracker.ietf.org/wg/tvr/>
     WG List:  <mailto:tvr@ietf.org>

     Author:   Eric Kinzie
               <mailto:ekinzie@labn.net>
     Author:   Don Fedyk
               <mailto:dfedyk@labn.net>
     Author:   Yingzhen Qu
               <mailto:yingzhen.ietf@gmail.com>
     Author:   Acee Lindem
               <mailto:acee.ietf@gmail.com>
     Author:   Marc Blanchet
               <mailto:marc.blanchet@viagenie.ca>";

  description
    "This YANG module contains YANG definitions for describing
    network topology with an time-variant availability schedule.

    Copyright (c) 2023 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 Revised 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
    (https://www.rfc-editor.org/info/rfcXXXX); see the RFC itself
    for full legal notices.

    The key words '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 BCP 14 (RFC 2119) (RFC 8174) when, and only when,
    they appear in all capitals, as shown here.";

  revision 2023-10-11 {
    description
      "Initial revision";
    reference
      "RFC XXXX: YANG Data Model for Scheduled Attributes";
  }

  container topology-schedule {
    description
      "Network topology schedules.";
    list nodes {
      key "node-id";
      description
        "List of nodes with schedules.";
      leaf node-id {
        type inet:uri;
        description
          "Identifier for a node, uniquely identifies a node. This
           may be the same as the node-id defined in the ietf-network
           module defined in RFC 8345.";
      }
      list available {
        key "start-date-time";
        description
          "The time at which this node becomes available.";
        uses tvr-schd:schedule {
          augment value-default {
            description
              "Augment default node availability.";
            leaf default-node-available {
              type boolean;
              default false;
              description
                "By default, the node is powered off.";
            }
          }
          augment base-schedule/intervals/value {
            description
              "Augment scheduled node availability.";
            leaf node-available {
              type boolean;
              description
                "Node availability.";
            }
          }
        }
      }
    }

    list links {
      key "source-node source-link-id";
      description
        "List of links.";
      leaf source-node {
        type inet:uri;
        description
          "A name refers to the source node of the link.";
      }
      leaf destination-node {
        type inet:uri;
        description
          "A name refers to the destination node of the link.";
      }
      leaf source-link-id {
        type string;
        description
          "A name refers to the link of the source node.";
      }
      list available {
        key "start-date-time";
        description
          "The time at which this link becomes available.";
        uses tvr-schd:schedule;

        container bandwidth {
          description
            "Scheduled link bandwidth.
             If the value measured by the system is less than this
             value, the system value is used.  If the value measured
             by the system is greater than this value the predicted
             value SHOULD be used.";
          uses tvr-schd:base-schedule {
            augment value-default {
              description
                "Augment default interface bandwidth.";
              leaf default-bandwidth {
                type te-types:te-bandwidth;
                default "0";
                description
                  "The default link capacity specified in a
                   generic format.";
              }
            }
            augment base-schedule/intervals/value {
              description
                "Augment scheduled interface bandwidth.";
              leaf bandwidth {
                type te-types:te-bandwidth;
                description
                  "The predicted link capacity specified in a
                   generic format.";
              }
            }
          }
        }
        container delay {
          description
            "The one-way delay or latency in microseconds. If the
             value measured by the system is less than this value
             the predicted value SHOULD be used.";
          uses tvr-schd:base-schedule {
            augment value-default {
              description
                "Augment default delay.";
              leaf default-delay {
                type uint32 {
                  range "0..16777215";
                }
                description
                  "The default link capacity specified in a
                   generic format.";
              }
            }
            augment base-schedule/intervals/value {
              description
                "Augment scheduled delay.";
              leaf delay {
                type uint32 {
                  range "0..16777215";
                }
                description
                  "The predicted link delay specified in a
                   generic format.";
              }
            }
          }
        }
      }
    }
  }
}
<CODE ENDS>

6. Security Considerations

The YANG modules specified in this document define a schema for data that 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 pre-configured subset of all available NETCONF or RESTCONF protocol operations and content.

There are a number of data nodes defined in ietf-tvr-node.yang module and ietf-tvr-topology.yang 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. There are the subtrees and data nodes and their sensitivity/vulnerability:

Some of the readable data nodes in the ietf-tvr-node.yang module and ietf-tvr-topolgy.yang module may be considered sensitive or vulnerable in some network environments. It is thus important to control read access (e.g., via get, get-config, or notification) to these data nodes.

7. 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-tvr-schedule
   Registrant Contact: The IESG.
   XML: N/A, the requested URI is an XML namespace.
   URI: urn:ietf:params:xml:ns:yang:ietf-tvr-node
   Registrant Contact: The IESG.
   XML: N/A, the requested URI is an XML namespace.
   URI: urn:ietf:params:xml:ns:yang:ietf-tvr-topology
   Registrant Contact: The IESG.
   XML: N/A, the requested URI is an XML namespace.

This document registers a YANG module in the YANG Module Names registry [RFC6020].

   name: ietf-tvr-schedule
   namespace: urn:ietf:params:xml:ns:yang:ietf-tvr-schedule
   prefix: tvr-schd
   reference: RFC XXXX
   name: ietf-tvr-node
   namespace: urn:ietf:params:xml:ns:yang:ietf-tvr-node
   prefix: tvr-node
   reference: RFC XXXX
   name: ietf-tvr-topology
   namespace: urn:ietf:params:xml:ns:yang:ietf-tvr-topology
   prefix: tvr-topo
   reference: RFC XXXX

8. Acknowledgements

The YANG model was developed using the suite of YANG tools written and maintained by numerous authors.

9. Normative References

[RFC2119]
Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <https://www.rfc-editor.org/info/rfc2119>.
[RFC3688]
Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, DOI 10.17487/RFC3688, , <https://www.rfc-editor.org/info/rfc3688>.
[RFC6020]
Bjorklund, M., Ed., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, DOI 10.17487/RFC6020, , <https://www.rfc-editor.org/info/rfc6020>.
[RFC6241]
Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed., and A. Bierman, Ed., "Network Configuration Protocol (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, , <https://www.rfc-editor.org/info/rfc6241>.
[RFC6242]
Wasserman, M., "Using the NETCONF Protocol over Secure Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, , <https://www.rfc-editor.org/info/rfc6242>.
[RFC6991]
Schoenwaelder, J., Ed., "Common YANG Data Types", RFC 6991, DOI 10.17487/RFC6991, , <https://www.rfc-editor.org/info/rfc6991>.
[RFC7950]
Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language", RFC 7950, DOI 10.17487/RFC7950, , <https://www.rfc-editor.org/info/rfc7950>.
[RFC8040]
Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF Protocol", RFC 8040, DOI 10.17487/RFC8040, , <https://www.rfc-editor.org/info/rfc8040>.
[RFC8174]
Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, , <https://www.rfc-editor.org/info/rfc8174>.
[RFC8341]
Bierman, A. and M. Bjorklund, "Network Configuration Access Control Model", STD 91, RFC 8341, DOI 10.17487/RFC8341, , <https://www.rfc-editor.org/info/rfc8341>.
[RFC8342]
Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K., and R. Wilton, "Network Management Datastore Architecture (NMDA)", RFC 8342, DOI 10.17487/RFC8342, , <https://www.rfc-editor.org/info/rfc8342>.
[RFC8446]
Rescorla, E., "The Transport Layer Security (TLS) Protocol Version 1.3", RFC 8446, DOI 10.17487/RFC8446, , <https://www.rfc-editor.org/info/rfc8446>.

10. Informative References

[RFC8340]
Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams", BCP 215, RFC 8340, DOI 10.17487/RFC8340, , <https://www.rfc-editor.org/info/rfc8340>.
[I-D.ietf-tvr-use-cases]
Birrane, E. J., Kuhn, N., and Y. Qu, "TVR (Time-Variant Routing) Use Cases", Work in Progress, Internet-Draft, draft-ietf-tvr-use-cases-01, , <https://datatracker.ietf.org/doc/html/draft-ietf-tvr-use-cases-01>.

Appendix A. Example: Add a scheduled cost to OSPF interface

In OSPF (Open Shortest Path First), the interface cost is a metric used to determine the preference or desirability of a particular link or interface. By default, the OSPF interface cost is calculated based on the bandwidth of the interface, and it is also configurable.

This example demonstrates how an OSPF interface can be extended with a cost that changes with a schedule.

module example-tvr-ospf-schedule {
  yang-version 1.1;
  namespace "http://example.com/ns/:example-tvr-ospf-schedule";
  prefix example-ospf-schedule;

  import ietf-routing {
    prefix "rt";
    reference
      "RFC 8349: A YANG Data Model for Routing
       Management (NMDA Version)";
  }
  import ietf-ospf {
    prefix "ospf";
    reference
      "RFC 9129: A YANG Data Model for OSPF Protocol";
  }

  import ietf-tvr-schedule {
    prefix "tvr-schd";
  }

  augment "/rt:routing/rt:control-plane-protocols/"
    + "rt:control-plane-protocol/ospf:ospf/ospf:areas/ospf:area/"
    + "ospf:interfaces/ospf:interface" {
    list scheduled-cost {
      key "start-date-time";
      description
        "Augment OSPF interface with a scheduled interface cost.";
      uses tvr-schd:schedule {
        augment base-schedule/intervals/value {
          leaf cost {
            type uint32;
            description
             "interface cost";
          }
        }
      }
    }
  }
}

Appendix B. Example: A node with scheduled power

In this configuration example, a node's power is scheduled between 2023/8/12 0:00 UTC to the end of 2023/08/13 with a daily schedule. In each day, the node is scheduled to be off between 1:00 to 5:00 and 20:00 to 23:00. The two intervals and the corresponding value are defined, the "value-default" is to define the value that's not covered by the intervals.

THe following figure shows the intended power schedule.


   1   0          1        0   1    0          1        0  1
  +-|----|---------------|---|-+-|----|---------------|---|-+
  0 1    5               20 23 0 1    5              20  23 24
  |        2023/08/12          |        2023/08/13          |

The following XML demonstrate the configuration.

<?xml version='1.0' encoding='UTF-8'?>
  <node-schedule xmlns="urn:ietf:params:xml:ns:yang:ietf-tvr-node">
      <router-id>192.168.0.1</router-id>
      <power-schedule xmlns="urn:ietf:params:xml:ns:yang:
                              ietf-tvr-node">
        <start-date-time>2023-08-12T00:00:00.00Z</start-date-time>
        <end-date-time>2023-08-13T24:00:00.00Z</end-date-time>
        <recurrence>daily</recurrence>
        <value-default>
          <default-power>false</default-power>
        </value-default>
        <base-schedule>
          <intervals>
            <start-time>360000</start-time>
            <end-time>1800000</end-time>
            <value>
              <power>true</power>
            </value>
          </intervals>
          <intervals>
            <start-time>7200000</start-time>
            <end-time>8280000</end-time>
            <value>
              <power>true</power>
            </value>
          </intervals>
        </base-schedule>
      </power-schedule>
  </node-schedule>

Authors' Addresses

Yingzhen Qu
Futurewei
2330 Central Expressway
Santa Clara, CA 95050
United States of America
Acee Lindem
LabN Consulting, L.L.C.
301 Midenhall Way
Cary, NC 27513
Eric Kinzie
LabN Consulting, L.L.C.
Don Fedyk
LabN Consulting, L.L.C.
Marc Blanchet
Viagenie