YANG Data Model for Scheduled Attributes
draft-ietf-tvr-schedule-yang-07
| Document | Type | Active Internet-Draft (tvr WG) | |
|---|---|---|---|
| Authors | Yingzhen Qu , Acee Lindem , Eric Kinzie , Don Fedyk , Marc Blanchet | ||
| Last updated | 2026-01-19 | ||
| Replaces | draft-united-tvr-schedule-yang | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
| Intended RFC status | Proposed Standard | ||
| Formats | |||
| Yang Validation | 0 errors, 0 warnings | ||
| Reviews |
YANGDOCTORS Early review
(of
-03)
by Xufeng Liu
Ready w/issues
|
||
| Additional resources | Mailing list discussion | ||
| Stream | WG state | In WG Last Call | |
| Associated WG milestone |
|
||
| Document shepherd | Tony Li | ||
| IESG | IESG state | I-D Exists | |
| Consensus boilerplate | Yes | ||
| Telechat date | (None) | ||
| Responsible AD | (None) | ||
| Send notices to | tony.li@tony.li |
draft-ietf-tvr-schedule-yang-07
Internet Y. Qu
Internet-Draft Futurewei Technologies
Intended status: Standards Track A. Lindem
Expires: 23 July 2026 Arrcus, Inc.
E. Kinzie
D. Fedyk
LabN Consulting, L.L.C.
M. Blanchet
Viagenie
19 January 2026
YANG Data Model for Scheduled Attributes
draft-ietf-tvr-schedule-yang-07
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 23 July 2026.
Copyright Notice
Copyright (c) 2026 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.
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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 Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
Table of Contents
1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. Tree Diagrams . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Design of the model . . . . . . . . . . . . . . . . . . . . . 3
3.1. Schedule Definitions . . . . . . . . . . . . . . . . . . 3
3.2. TVR Node YANG Module . . . . . . . . . . . . . . . . . . 4
3.3. TVR Topology YANG Module . . . . . . . . . . . . . . . . 4
4. TVR YANG Trees . . . . . . . . . . . . . . . . . . . . . . . 5
4.1. TVR Node YANG Tree . . . . . . . . . . . . . . . . . . . 5
4.2. TVR Topology YANG Tree . . . . . . . . . . . . . . . . . 6
5. TVR Schedule YANG Modules . . . . . . . . . . . . . . . . . . 8
5.1. TVR Schedule YANG Module . . . . . . . . . . . . . . . . 8
5.2. TVR Schedule Node Module . . . . . . . . . . . . . . . . 10
5.3. TVR Network Topology Module . . . . . . . . . . . . . . . 14
6. Operational Considerations . . . . . . . . . . . . . . . . . 18
7. Security Considerations . . . . . . . . . . . . . . . . . . . 19
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 20
10. Normative References . . . . . . . . . . . . . . . . . . . . 20
11. Informative References . . . . . . . . . . . . . . . . . . . 22
Appendix A. Example: Add a scheduled cost to OSPF interface . . 22
Appendix B. Example: TVR Schedule Node Configuration . . . . . . 23
Appendix C. Example: TVR Network Topology Configuration . . . . 25
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 27
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.
There are use cases where changes to the routing topology are
expected as part of network operations. 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
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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 [RFC9657].
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 "tvr-schedule" consists of a list of schedules, and each
schedule is either a single time period or recurring time periods.
For each schedule instance, it utilizes the groupings "period-of-
time" and "recurrence-utc" as defined in
[I-D.ietf-netmod-schedule-yang].
Users can supply attributes or containers that augment the schedule.
The "tvr-node" has a container "scheduled-attributes" that uses the
"tvr-schedule".
When an attribute's schedule ends, the "value-default" MAY be used,
when present. Alternatively, values can remain as set until another
schedule alters values.
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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 schedule of A1 may contain a list
of 3 time periods with different values. The attribute A2 will take
on the value vv1 from time t0 until t1, default value va2 from t1
until t2, and vv2 from t1 until t3. The schedule of A2 may contain a
list of two time periods, and the default value is used between
scheduled values.
Attributes
+-------------------+----------+------+
A1 | v1 | v2 | v3 |
+-------------------+----------+------+
A2 | vv1 | va2 | vv2 |
+-------------------+-----------------+
t0 t1 t2 t3
Time
Figure 1: Time Varying Properties
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 scheduled power at the node level. At the interface
level, a node has a list of interfaces, and each interface has its
own schedule for availability/power up and down, scheduled bandwidth,
and scheduled neighbors.
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.
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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. "destination-node" of a link may follow a
schedule as well.
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 node-id? inet:uri
+--rw node-power-schedule
| +--rw power-default? boolean
| +--rw schedule* [schedule-id]
| +--rw schedule-id uint32
| +--rw (schedule-type)?
| | +--:(period)
| | | +--rw period-description? string
| | | +--rw period-start? yang:date-and-time
| | | +--rw time-zone-identifier? sys:timezone-name
| | | +--rw (period-type)?
| | | +--:(explicit)
| | | | +--rw period-end? yang:date-and-time
| | | +--:(duration)
| | | +--rw duration? duration
| | +--:(recurrence)
| | +--rw recurrence-first
| | | +--rw start-time-utc? yang:date-and-time
| | | +--rw duration? uint32
| | +--rw (recurrence-end)?
| | | +--:(until)
| | | | +--rw utc-until? yang:date-and-time
| | | +--:(count)
| | | +--rw count? uint32
| | +--rw recurrence-description? string
| | +--rw frequency? identityref
| | +--rw interval? uint32
| +--rw power-state? boolean
+--rw interface-schedule
+--rw interface* [name]
+--rw name union
+--rw default-available? boolean
+--rw default-bandwidth? yang:gauge64
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+--rw attribute-schedule
+--rw schedule* [schedule-id]
+--rw schedule-id uint32
+--rw (schedule-type)?
| +--:(period)
| | +--rw period-description? string
| | +--rw period-start?
| | | yang:date-and-time
| | +--rw time-zone-identifier?
| | | sys:timezone-name
| | +--rw (period-type)?
| | +--:(explicit)
| | | +--rw period-end?
| | | yang:date-and-time
| | +--:(duration)
| | +--rw duration? duration
| +--:(recurrence)
| +--rw recurrence-first
| | +--rw start-time-utc? yang:date-and-time
| | +--rw duration? uint32
| +--rw (recurrence-end)?
| | +--:(until)
| | | +--rw utc-until?
| | | yang:date-and-time
| | +--:(count)
| | +--rw count? uint32
| +--rw recurrence-description? string
| +--rw frequency? identityref
| +--rw interval? uint32
+--rw scheduled-attributes
+--rw available? boolean
+--rw bandwidth? yang:gauge64
+--rw neighbor? inet:uri
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 node* [node-id]
| +--rw node-id inet:uri
| +--rw available
| +--rw default-node-available? boolean
| +--rw schedule* [schedule-id]
| +--rw schedule-id uint32
| +--rw (schedule-type)?
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| | +--:(period)
| | | +--rw period-description? string
| | | +--rw period-start?
| | | | yang:date-and-time
| | | +--rw time-zone-identifier? sys:timezone-name
| | | +--rw (period-type)?
| | | +--:(explicit)
| | | | +--rw period-end?
| | | | yang:date-and-time
| | | +--:(duration)
| | | +--rw duration? duration
| | +--:(recurrence)
| | +--rw recurrence-first
| | | +--rw start-time-utc? yang:date-and-time
| | | +--rw duration? uint32
| | +--rw (recurrence-end)?
| | | +--:(until)
| | | | +--rw utc-until?
| | | | yang:date-and-time
| | | +--:(count)
| | | +--rw count? uint32
| | +--rw recurrence-description? string
| | +--rw frequency? identityref
| | +--rw interval? uint32
| +--rw node-available? boolean
+--rw link* [source-node source-link-id]
+--rw source-node inet:uri
+--rw source-link-id string
+--rw available
+--rw schedule* [schedule-id]
| +--rw schedule-id uint32
| +--rw (schedule-type)?
| | +--:(period)
| | | +--rw period-description? string
| | | +--rw period-start?
| | | | yang:date-and-time
| | | +--rw time-zone-identifier? sys:timezone-name
| | | +--rw (period-type)?
| | | +--:(explicit)
| | | | +--rw period-end?
| | | | yang:date-and-time
| | | +--:(duration)
| | | +--rw duration? duration
| | +--:(recurrence)
| | +--rw recurrence-first
| | | +--rw start-time-utc? yang:date-and-time
| | | +--rw duration? uint32
| | +--rw (recurrence-end)?
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| | | +--:(until)
| | | | +--rw utc-until?
| | | | yang:date-and-time
| | | +--:(count)
| | | +--rw count? uint32
| | +--rw recurrence-description? string
| | +--rw frequency? identityref
| | +--rw interval? uint32
| +--rw link-attributes
| +--rw link-available? boolean
| +--rw bandwidth? yang:gauge64
| +--rw delay? uint32
| +--rw destination-node? inet:uri
+--rw default-link-available? boolean
+--rw default-bandwidth? yang:gauge64
+--rw default-delay? uint32
5. TVR Schedule YANG Modules
The following RFC is not referenced in the document text but is
referenced in the "ietf-tvr-schedule.yang" module and "ietf-tvr-
topology.yang" module: [RFC6991].
5.1. TVR Schedule YANG Module
<CODE BEGINS> file "ietf-tvr-schedule@2025-06-30.yang"
module ietf-tvr-schedule {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-tvr-schedule";
prefix tvr-schd;
import ietf-schedule {
prefix "schedule";
reference
"RFC XXXX: A Common YANG Data Model for Scheduling";
}
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
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<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) 2025 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.";
reference
"RFC XXXX: YANG Data Model for Scheduled Attributes";
revision 2025-06-30 {
description
"Initial Version";
reference
"RFC XXXX: YANG Data Model for Scheduled Attributes.";
}
grouping tvr-schedule {
list schedule {
key schedule-id;
leaf schedule-id {
type uint32;
description
"Identifies the schedule.";
}
choice schedule-type {
description
"Choice of schedule type.";
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case period {
description
"A schedule with a single instance.";
uses schedule:period-of-time;
}
case recurrence {
description
"A schedule with recurrence. The time is defined in UTC
format.";
uses schedule:recurrence-utc;
}
}
description
"list of schedules.";
}
description
"A common grouping definition of schedules.";
}
}
<CODE ENDS>
5.2. TVR Schedule Node Module
<CODE BEGINS> file "ietf-tvr-node@2025-06-30.yang"
module ietf-tvr-node {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-tvr-node";
prefix tvr-node;
import ietf-inet-types {
prefix inet;
reference
"RFC 6991: Common YANG Data Types";
}
import ietf-yang-types {
prefix "yang";
reference
"RFC 6991: Common YANG Data Types";
}
import ietf-tvr-schedule {
prefix "tvr-schd";
}
organization
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"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 is to configure and manage node attributes
with schedules.
This YANG model conforms to the Network Management
Datastore Architecture (NMDA) as described in RFC 8342.
Copyright (c) 2025 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.";
reference
"RFC XXXX: YANG Data Model for Scheduled Attributes";
revision 2025-06-30 {
description
"Initial Version";
reference
"RFC XXXX: YANG Data Model for Scheduled Attributes.";
}
container node-schedule {
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description
"This container defines a node's time variant attributes
with schedules.";
leaf node-id {
type inet:uri;
description
"Identifier for a node, uniquely identifies a node.";
}
container node-power-schedule {
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.";
leaf power-default {
type boolean;
default false;
description
"This indicates the default node power for the time
periods when no specific power value is specified. If
unspecified, the node is powered down by default.";
}
uses tvr-schd:tvr-schedule {
augment "schedule" {
description
"Augment the power state within each period.";
leaf power-state {
type boolean;
description
"Indicates whether the node is powered on.";
}
}
}
}
container interface-schedule {
description
"Container for TVR node interface attributes.";
list interface {
key "name";
description
"List of interface with schedules.";
leaf name {
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type union {
type yang:xpath1.0;
type string;
}
description
"Name of the interface.
If used with the ietf-interfaces module, the xpath name
is to identify the interface.";
}
leaf default-available {
type boolean;
default false;
description
"By default, the link is not available.";
}
leaf default-bandwidth {
type yang:gauge64;
units "bits/second";
default "0";
description
"The default interface bandwidth in bits
per second";
}
container attribute-schedule {
description
"Interface attributes with schedules.";
uses tvr-schd:tvr-schedule {
augment "schedule" {
description
"Augment scheduled interface state.";
container scheduled-attributes {
description
"Augmentation container for links.";
leaf available {
type boolean;
description
"Scheduled interface power state. This is to
work with the leaf 'enabled' for the configured
state of the interface.";
}
leaf bandwidth {
type yang:gauge64;
units "bits/second";
description
"The scheduled bandwidth in bits per second";
}
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leaf neighbor {
type inet:uri;
description
"The node expected to be this interface's neighbor
during this time.";
}
}
}
}
}
}
}
}
}
<CODE ENDS>
5.3. TVR Network Topology Module
<CODE BEGINS> file "ietf-tvr-topology@2026-01-18.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-yang-types {
prefix "yang";
reference
"RFC 6991: Common YANG Data 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
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<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 a time-variant availability schedule.
Copyright (c) 2026 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 2026-01-18 {
description
"Initial revision";
reference
"RFC XXXX: YANG Data Model for Scheduled Attributes";
}
container topology-schedule {
description
"Network topology schedules.";
list node {
key "node-id";
description
"List of nodes with schedules.";
leaf node-id {
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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.";
}
container available {
description
"The time at which this node becomes available.";
leaf default-node-available {
type boolean;
default false;
description
"By default, the node is powered off.";
}
uses tvr-schd:tvr-schedule {
augment "schedule" {
description
"Augment scheduled node availability.";
leaf node-available {
type boolean;
description
"Node availability.";
}
}
}
}
}
list link {
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 source-link-id {
type string;
description
"A name refers to the link of the source node.";
}
container available {
description
"The time at which this link becomes available.";
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uses tvr-schd:tvr-schedule {
augment "schedule" {
description
"Augment scheduled values.";
container link-attributes {
description "Augmentation container for links.";
leaf link-available {
type boolean;
description
"The predicted link availability.";
}
leaf bandwidth {
type yang:gauge64;
units "bits/second";
description
"The predicted link capacity. 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.";
}
leaf delay {
type uint32 {
range "0..16777215";
}
description
"The predicted 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.";
}
leaf destination-node {
type inet:uri;
description
"A name refers to the destination node of the link.";
}
}
}
}
leaf default-link-available {
type boolean;
default "false";
description
"The default link availability. During times when the
schedule does not specify an availability, this value
is used.";
}
leaf default-bandwidth {
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type yang:gauge64;
units "bits/second";
default "0";
description
"The default link capacity specified in a
generic format.";
}
leaf default-delay {
type uint32 {
range "0..16777215";
}
description
"The default one-way delay in microseconds.";
}
}
}
}
}
<CODE ENDS>
6. Operational Considerations
The TVR Schedule YANG modules provide a structured mechanism to
represent time-variant attributes of network elements and topologies.
The following aspects should be considered by operators deploying the
modules.
Operators should be aware that these scheduled attributes represent
planned state changes, not instantaneous configuration changes or
unplanned breakages.
A schedule can be defined using a series of periods or intervals with
recurrence. The model defined in this document doesn't prevent a
configuration to mix both styles. However, it's not recommended.
There should be synchronized clocks between controllers and devices.
The time sources (e.g., NTP, PTP) should be accurate to avoid
unintended time/schedule offsets. Inconsistent time bases can lead
to network misbehavior, such as routing loops or network instability.
The modules are to support TVR use cases where topology and
attributes vary as a function of time. How control plane and data
plane are impacted by the schedules should be considered by the
operators.
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The TVR schedule modules are meant to work together with other models
that manage node or interface attributes. Operators should consider
the conflicting configurations between the scheduled and non-
scheduled settings and how to handle the conflicts.
7. 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:
/node-schedule/node-power-schedule
/node-schedule/interface-schedule
/topology-schedule/nodes/available
/topology-schedule/links/available
Modifications to these scheduled attributes may result in a denial
of service.
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.
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:
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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
9. Acknowledgements
The YANG model was developed using the suite of YANG tools written
and maintained by numerous authors.
10. Normative References
[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>.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
DOI 10.17487/RFC3688, January 2004,
<https://www.rfc-editor.org/info/rfc3688>.
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[RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for
the Network Configuration Protocol (NETCONF)", RFC 6020,
DOI 10.17487/RFC6020, October 2010,
<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, June 2011,
<https://www.rfc-editor.org/info/rfc6241>.
[RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure
Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011,
<https://www.rfc-editor.org/info/rfc6242>.
[RFC6991] Schoenwaelder, J., Ed., "Common YANG Data Types",
RFC 6991, DOI 10.17487/RFC6991, July 2013,
<https://www.rfc-editor.org/info/rfc6991>.
[RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
RFC 7950, DOI 10.17487/RFC7950, August 2016,
<https://www.rfc-editor.org/info/rfc7950>.
[RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
<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,
May 2017, <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, March 2018,
<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, March 2018,
<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, August 2018,
<https://www.rfc-editor.org/info/rfc8446>.
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[I-D.ietf-netmod-schedule-yang]
Ma, Q., Wu, Q., Boucadair, M., and D. King, "A Common YANG
Data Model for Scheduling", Work in Progress, Internet-
Draft, draft-ietf-netmod-schedule-yang-10, 7 August 2025,
<https://datatracker.ietf.org/doc/html/draft-ietf-netmod-
schedule-yang-10>.
11. Informative References
[RFC8340] Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams",
BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018,
<https://www.rfc-editor.org/info/rfc8340>.
[RFC8792] Watsen, K., Auerswald, E., Farrel, A., and Q. Wu,
"Handling Long Lines in Content of Internet-Drafts and
RFCs", RFC 8792, DOI 10.17487/RFC8792, June 2020,
<https://www.rfc-editor.org/info/rfc8792>.
[RFC9657] Birrane, III, E., Kuhn, N., Qu, Y., Taylor, R., and L.
Zhang, "Time-Variant Routing (TVR) Use Cases", RFC 9657,
DOI 10.17487/RFC9657, October 2024,
<https://www.rfc-editor.org/info/rfc9657>.
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.
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module ietf-tvr-ospf-schedule {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-tvr-ospf-schedule";
prefix 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" {
container scheduled-cost {
description
"Augment OSPF interface with a scheduled interface cost.";
uses tvr-schd:tvr-schedule {
augment "schedule" {
leaf cost {
type uint32;
description
"interface cost";
}
}
}
}
}
}
Appendix B. Example: TVR Schedule Node Configuration
The following is an XML example using the ietf-tvr-node YANG module.
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In this example, the node has a node-id of "node:1", and it's
scheduled to be powered off starting from 2025-07-26T17:00:00Z to
2025-07-26T18:00:00Z. Interface "eth 1" has a recurrent schedule to
be "not available (off)" which starts from 2025-07-20T23:00:00Z,
lasts for 7200 seconds (2 hours) each time for 10 times every 2 days.
Note: '\' line wrapping per [RFC8792].
<node-schedule xmlns="urn:ietf:params:xml:ns:yang:ietf-tvr-node">
<node-id>node:1</node-id>
<node-power-schedule>
<power-default>true</power-default>
<schedule>
<schedule-id>1</schedule-id>
<period-description>pwr off</period-description>
<period-start>2025-07-26T17:00:00Z</period-start>
<time-zone-identifier>UTC</time-zone-identifier>
<period-end>2025-07-26T18:00:00Z</period-end>
<power-state>false</power-state>
</schedule>
</node-power-schedule>
<interface-schedule>
<interface>
<name>eth 1</name>
<attribute-schedule>
<schedule>
<schedule-id>100</schedule-id>
<recurrence-first>
<start-time-utc>2025-07-20T23:00:00Z</start-time-utc>
<duration>7200</duration>
</recurrence-first>
<count>10</count>
<recurrence-description>daily off</recurrence-description>
<frequency xmlns:schedule="urn:ietf:params:xml:ns:yang:\
ietf-schedule">schedule:daily</frequency>
<interval>2</interval>
<scheduled-attributes>
<available>false</available>
</scheduled-attributes>
</schedule>
</attribute-schedule>
</interface>
</interface-schedule>
</node-schedule>
The following is the same example using JSON format.
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{
"node-schedule": {
"-xmlns": "urn:ietf:params:xml:ns:yang:ietf-tvr-node",
"node-id": "node:1",
"node-power-schedule": {
"power-default": "true",
"schedule": {
"schedule-id": "1",
"period-description": "pwr off",
"period-start": "2025-07-26T17:00:00Z",
"time-zone-identifier": "UTC",
"period-end": "2025-07-26T18:00:00Z",
"power-state": "false"
}
},
"interface-schedule": {
"interface": {
"name": "eth 1",
"attribute-schedule": {
"schedule": {
"schedule-id": "100",
"recurrence-first": {
"start-time-utc": "2025-07-20T23:00:00Z",
"duration": "7200"
},
"count": "10",
"recurrence-description": "daily off",
"frequency": "ietf-schedule:daily",
"interval": "2",
"scheduled-attributes": {
"available": "false"
}
}
}
}
}
}
}
Appendix C. Example: TVR Network Topology Configuration
The following is an XML example using the ietf-tvr-topology YANG
module.
In this example, the node with a node-id of "node:1" is scheduled to
be powered off start from 2025-07-26T17:00:00Z, for 2 days and four
and half hours.
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Node "node:2" is scheduled to be off starting from
2025-07-20T23:00:00Z, lasting for 7200 seconds (2 hours) every two
days until 2025-08-20T23:00:00Z.
Note: '\' line wrapping per [RFC8792].
<topology-schedule xmlns="urn:ietf:params:xml:ns:yang\
:ietf-tvr-topology">
<node>
<node-id>node:1</node-id>
<available>
<default-node-available>true</default-node-available>
<schedule>
<schedule-id>101</schedule-id>
<period-description>node1 schedule</period-description>
<period-start>2025-07-26T17:00:00Z</period-start>
<time-zone-identifier>UTC</time-zone-identifier>
<duration>P2DT04:30:00</duration>
<node-available>false</node-available>
</schedule>
</available>
</node>
<node>
<node-id>node:2</node-id>
<available>
<default-node-available>true</default-node-available>
<schedule>
<schedule-id>201</schedule-id>
<recurrence-first>
<start-time-utc>2025-07-20T23:00:00Z</start-time-utc>
<duration>7200</duration>
</recurrence-first>
<utc-until>2025-08-20T23:00:00Z</utc-until>
<recurrence-description>daily off</recurrence-description>
<frequency xmlns:schedule="urn:ietf:params:xml:ns:yang:\
ietf-schedule">schedule:daily</frequency>
<interval>2</interval>
<node-available>false</node-available>
</schedule>
</available>
</node>
</topology-schedule>
The following is the same example using JSON format.
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{
"topology-schedule": {
"-xmlns": "urn:ietf:params:xml:ns:yang:ietf-tvr-topology",
"node": [
{
"node-id": "node:1",
"available": {
"default-node-available": "true",
"schedule": {
"schedule-id": "101",
"period-description": "node1 schedule",
"period-start": "2025-07-26T17:00:00Z",
"time-zone-identifier": "UTC",
"duration": "P2DT04:30:00",
"node-available": "false"
}
}
},
{
"node-id": "node:2",
"available": {
"default-node-available": "true",
"schedule": {
"schedule-id": "201",
"recurrence-first": {
"start-time-utc": "2025-07-20T23:00:00Z",
"duration": "7200"
},
"utc-until": "2025-08-20T23:00:00Z",
"recurrence-description": "daily off",
"frequency": "ietf-schedule:daily",
"interval": "2",
"node-available": "false"
}
}
}
]
}
}
Authors' Addresses
Yingzhen Qu
Futurewei Technologies
Email: yingzhen.ietf@gmail.com
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Acee Lindem
Arrcus, Inc.
Email: acee.ietf@gmail.com
Eric Kinzie
LabN Consulting, L.L.C.
Email: ekinzie@labn.net
Don Fedyk
LabN Consulting, L.L.C.
Email: dfedyk@labn.net
Marc Blanchet
Viagenie
Email: marc.blanchet@viagenie.ca
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