YANG Data Models for fine grain Optical Transport Network
draft-tan-ccamp-fgotn-yang-06
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| Document | Type | Active Internet-Draft (individual) | |
|---|---|---|---|
| Authors | Yanxia Tan , Zheng Yanlei , Italo Busi , Chaode Yu , XingZhao | ||
| Last updated | 2026-03-01 | ||
| RFC stream | (None) | ||
| Intended RFC status | (None) | ||
| Formats | |||
| Yang Validation | 0 errors, 0 warnings | ||
| Stream | Stream state | (No stream defined) | |
| Consensus boilerplate | Unknown | ||
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| IESG | IESG state | I-D Exists | |
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| Send notices to | (None) |
draft-tan-ccamp-fgotn-yang-06
Common Control and Measurement Plane Y. Tan
Internet-Draft Y. Zheng
Intended status: Standards Track China Unicom
Expires: 2 September 2026 I. Busi
C. Yu
Huawei Technologies
X. Zhao
CAICT
1 March 2026
YANG Data Models for fine grain Optical Transport Network
draft-tan-ccamp-fgotn-yang-06
Abstract
This document defines YANG data models to describe the topology and
tunnel information of a fine grain Optical Transport Network. The
YANG data models defined in this document are designed to meet the
requirements for efficient transmission of sub-1Gbit/s client signals
in transport network.
About This Document
This note is to be removed before publishing as an RFC.
The latest revision of this draft can be found at
https://YuChaode.github.io/draft-tan-ccamp-fgotn-yang/draft-tan-
ccamp-fgotn-yang.html. Status information for this document may be
found at https://datatracker.ietf.org/doc/draft-tan-ccamp-fgotn-
yang/.
Discussion of this document takes place on the Common Control and
Measurement Plane Working Group mailing list (mailto:ccamp@ietf.org),
which is archived at https://mailarchive.ietf.org/arch/browse/ccamp/.
Subscribe at https://www.ietf.org/mailman/listinfo/ccamp/.
Source for this draft and an issue tracker can be found at
https://github.com/YuChaode/draft-tan-ccamp-fgotn-yang.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Terminology and Notations . . . . . . . . . . . . . . . . 4
1.2. Requirements Notation . . . . . . . . . . . . . . . . . . 4
1.3. Tree Diagram . . . . . . . . . . . . . . . . . . . . . . 4
1.4. Requirements Language . . . . . . . . . . . . . . . . . . 5
1.5. Prefixes in Model Names . . . . . . . . . . . . . . . . . 5
1.6. Model Tree Diagrams . . . . . . . . . . . . . . . . . . . 5
2. Fine grain Optical Transport Network Scenarios Overview . . . 6
2.1. Retrieve Server Tunnels Scenario of fgOTN . . . . . . . . 6
2.2. Multi-layer Path Splicing Scenario of fgOTN . . . . . . . 7
2.3. Hitless Bandwidth Adjustment Scenario of fgOTN . . . . . 8
3. YANG Data Model for fine grain Optical Transport Network
Overview . . . . . . . . . . . . . . . . . . . . . . . . 9
4. YANG Data Model for fgOTN Topology . . . . . . . . . . . . . 10
4.1. Fine Grain OTN Topology Data Model Overview . . . . . . . 10
4.2. Bandwidth Augmentation . . . . . . . . . . . . . . . . . 11
4.3. Label Augmentation . . . . . . . . . . . . . . . . . . . 11
5. YANG Data Model for fgOTN Tunnel . . . . . . . . . . . . . . 12
5.1. Fine Grain OTN Tunnel Data Model Overview . . . . . . . . 12
5.2. Bandwidth Augmentation . . . . . . . . . . . . . . . . . 13
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5.3. Label Augmentation . . . . . . . . . . . . . . . . . . . 13
6. YANG Data Model for fgOTN types . . . . . . . . . . . . . . . 13
7. YANG Tree for fgOTN topology . . . . . . . . . . . . . . . . 15
8. YANG Data Model for fgOTN topology . . . . . . . . . . . . . 15
9. YANG Tree for fgOTN tunnel . . . . . . . . . . . . . . . . . 20
10. YANG Data Model for fgOTN tunnel . . . . . . . . . . . . . . 21
11. Manageability Considerations . . . . . . . . . . . . . . . . 25
12. Security Considerations . . . . . . . . . . . . . . . . . . . 25
13. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 25
14. References . . . . . . . . . . . . . . . . . . . . . . . . . 25
14.1. Normative References . . . . . . . . . . . . . . . . . . 25
14.2. Informative References . . . . . . . . . . . . . . . . . 27
Appendix A. Multi-domain fgOTN Hitless Resizing Process . . . . 27
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 28
Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 28
1. Introduction
Optical Transport Networks (OTN) is a mainstream layer 1 technology
for the transport network. Over the years, it has continued to
evolve, to improve its transport functions for the emerging
requirements. The topology and tunnel information in the OTN has
already been defined by generic traffic-engineering models and
technology-specific models, including [I-D.ietf-ccamp-otn-topo-yang]
and [I-D.ietf-ccamp-otn-tunnel-model].
In the latest version of OTN, ITU-T G.709/Y.1331 Edition 6.5
[ITU-T_G.709], the fine grain OTN (fgOTN) is introduced for the
efficient transmission of low rate client signals (e.g., sub-1G).
This document presents the control interface requirements of fgOTN,
and defines two YANG data models for fgOTN topology and fgOTN tunnel.
The topology model can capture topological and resource-related
information pertaining to fgOTN. The fgOTN tunnel YANG data model
defined in this document is used for the provisioning and management
of fgOTN Traffic Engineering (TE) tunnels and Label Switched Paths
(LSPs).
Furthermore, this document also imports the generic Layer 1 types
defined in [I-D.ietf-ccamp-layer1-types].
The YANG data models defined in this document conform to the Network
Management Datastore Architecture (NMDA) defined in [RFC8342].
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1.1. Terminology and Notations
Some of the key terms used in this document are listed as follow.
* fgTS: fine grain Tributary Slot.
* fgODUflex: fine grain Optical channel Data Unit flex.
The following terms are defined in [RFC7950] and are not redefined
here:
* client
* server
* augment
* data model
* data node
The following terms are defined in [RFC6241] and are not redefined
here:
* configuration data
* state data
The terminology for describing YANG data models is found in
[RFC7950].
1.2. Requirements Notation
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 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
1.3. Tree Diagram
A simplified graphical representation of the data model is used in
Section 7 of this document. The meaning of the symbols in this
diagram is defined in [RFC8340].
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1.4. Requirements Language
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 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
1.5. Prefixes in Model Names
In this documents, names of data nodes and other data model objects
are prefixed using the standard prefix associated with the
corresponding YANG imported modules, as shown in the following table.
+===========+=====================+============+
| Prefix | Yang Module | Reference |
+===========+=====================+============+
| l1-types | ietf-layer1-types | [RFC YYYY] |
+-----------+---------------------+------------+
| otnt | ietf-otn-topology | [RFC ZZZZ] |
+-----------+---------------------+------------+
| te | ietf-te | [RFC KKKK] |
+-----------+---------------------+------------+
| otn-tnl | ietf-otn-tunnel | [RFC JJJJ] |
+-----------+---------------------+------------+
| fgotnt | ietf-fgotn-topology | RFC XXXX |
+-----------+---------------------+------------+
| fgotn-tnl | ietf-fgotn-tunnel | RFC XXXX |
+-----------+---------------------+------------+
Table 1: Prefixes and corresponding YANG modules
RFC Editor Note: Please replace XXXX with the number assigned to the
RFC once this draft becomes an RFC. Please replace YYYY with the RFC
numbers assigned to [I-D.ietf-ccamp-layer1-types]. Please replace
ZZZZ with the RFC numbers assigned to [I-D.ietf-ccamp-otn-topo-yang].
Please replace KKKK with the RFC numbers assigned to
[I-D.ietf-teas-yang-te]. Please replace JJJJ with the RFC numbers
assigned to [I-D.ietf-ccamp-otn-tunnel-model]. Please remove this
note.
1.6. Model Tree Diagrams
The tree diagrams extracted from the module(s) defined in this
document are given in subsequent sections as per the syntax defined
in [RFC8340].
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2. Fine grain Optical Transport Network Scenarios Overview
OTN network will cover a larger scope of networks, it may include the
backbone network, metro core, metro aggregation, metro access, and
even the OTN CPE in the customers' networks [ITU-T_G.709.20]. In
general, the metro OTN networks support both fgODUflex and ODUk
switching. At the boundary nodes (e.g., metro-core nodes) of the
metro OTN networks, the fgODUflexes to other metro OTN networks are
multiplexed into ODUk of backbone networks. Therefore, the backbone
OTN network could only support ODUk switching.
The typical scenarios for fgOTN is to provide low bit rate private
line or private network services for customers. The interface
function requirements of fgOTN mainly include topology resource
reporting and service provisioning. Three scenarios that require
special consideration are listed based on the characteristics of
fgOTN.
2.1. Retrieve Server Tunnels Scenario of fgOTN
Figure 1 below shows an example of scenario to retrieve server
tunnels for multi-domain fgOTN service. In this example, some small
bandwidth fgOTN service are aggregated by the access ring (10G), and
then aggregated into a bigger bandwidth in metro ring (100G). The
allocation of TS to support fgOTN switching maybe different in access
ring and metro ring. All link bandwidth information that supports
fgOTN should be reported to MDSC by the PNC controller. E.g. there
could be three ODU0 allocated in the access ring while there could be
two ODU2 are allocated in the metro ring to support fgOTN switching.
In this example, the server layer ODUk tunnel for fgOTN tunnel from
node A to node E is ODU0, and the server layer tunnel from node E to
node G is ODU2. The server layer tunnel for fgOTN tunnel will
include one ODU0 tunnel and one ODU2 tunnel.
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+-----+
| A | \ |
+-----+ \ Domain 1 | Domain 2
| \ |
| 10G \ |
| \ |
+-----+ +-----+ +-----+ | +-----+
| B | \ | E |---------| G |-----------| I |---------
+-----+ \ / +-----+ +-----+ +-----+
\/ | 100G | | 100G
/\ | | |
+-----+ / \ +-----+ +-----+ +-----+
| C | / | F |---------| H |-----------| J |---------
+-----+ +-----+ +-----+ +-----+
| /
| 10G /
| /
+-----+ /
| D | /
+-----+
Figure 1: The Scenario to Retrieve Server Tunnels
2.2. Multi-layer Path Splicing Scenario of fgOTN
Some operators that would like to provide the paths when there could
be different switching capabilities of nodes in their LSP, so that
the MDSC coordinator can clearly display multi-layer paths and the
relationship between primary-path and secondary-path. In the current
network, not all nodes in the operator network support fgOTN, as
shown in figure 2, node f1, f2, f3 and f4 support fgOTN, node N-f5
and node N-f6 do not support fgOTN. To present the end-to-end multi-
layer primary-path and secondary-path of the services on the client
side, it is necessary to complete the end-to-end path splicing based
on the the ODU tunnel information associated with the fgotn tunnel.
In Figure 2, assuming that the server layer ODUk tunnel for the fgOTN
primary tunnel from node f1 to node f2 is ODU0, the server layer
tunnel from node f2 to node f3 is ODU2, and the server layer tunnel
from node f3 to node f4 is ODU1. Assuming the server layer ODUk
tunnel for the fgOTN secondary tunnel from node f1 to node f2 is
ODU2. We need to setup four server layer ODUk tunnels before setting
up an fgODUflex tunnel with a primary path and a secondary path to
provide protection. To support multi-layer path splicing, we should
make some extension on the dependency tunnel structure or on the path
element, such as extending the working roles and index of the
tunnels.
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+-----+ +-----+
----| f2 |------------| f3 |----
/ +-----+ +-----+ \
/ ----------primary-path------------ \
/ / \ \
+-----+ +-----+
| f1 | | f4 |
+-----+ +-----+
\ \ / /
\ ---------secondary-path----------- /
\ +------+ +------+ /
----| N-f5 |----------| N-f6 |----
+------+ +------+
Figure 2: Multi-layer Path Splicing Scenario of fgOTN
2.3. Hitless Bandwidth Adjustment Scenario of fgOTN
[ITU-T_G.709] defines the data plane procedure to support fgODUflex
hitless resizing. The support of management of hitless resizing of
fgODUflex needs to be carefully considered.
The range of fgOTN service's Bandwidth on Demand (BoD) cannot exceed
its server layer's bandwidth.
The client needs to know how many bandwidth of a link is allocated
for fgOTN. When performs hitless resizing, the client sends the
fgODUflex identifier and the target bandwidth to the source node
controller. After receiving the network management configuration
information, the source node triggers the bandwidth adjustment.
During the hitless bandwidth adjustment process, it is necessary to
reserve or mark the corresponding bandwidth resources first, and then
trigger the the bandwidth adjustment actions.
Another point to note is that when performing bidirectional hitless
resizing for fgODUflex service, the adjustment should be initiated by
the client side to a single network management system. Specifically,
the adjustment is first performed in the Node 1 to Node 6 direction,
and then the reverse direction (Node 6 to Node 1) is automatically
triggered for adjustment.
Both single domain and multi-domain hitless resizing should be
supported. For single domain and multi-domain hitless resizing
scenario, the source controller alone report the bandwidth adjustment
status to the MDSC coordinator upon completion.
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+----------+
----------------------| MDSC |---------------------
/ | | \
/ +----------+ \
/ | \
/ | \
+------------+ +------------+ +------------+
| Controller | | Controller | | Controller |
| 1 | | 2 | | 3 |
+------------+ +------------+ +------------+
End-to-end fgOTN service
<--------------------------------------------------------------------------------->
+------+ +------+ +------+ +------+ +------+ +------+
| node |-------| node |-------| node |-------| node |-------| node |-------| node |
| 1 |-------| 2 |-------| 3 |-------| 4 |-------| 5 |-------| 6 |
+------+ +------+ | +------+ +------+ | +------+ +------+
source | | destination
Domain 1 | Domain 2 | Domain 3
| |
Figure 3: Hitless Resizing Scenario of fgOTN
3. YANG Data Model for fine grain Optical Transport Network Overview
In order to provide fgOTN capabilities, this document defines two
extension YANG data models augmenting to OTN topology and OTN tunnel
YANG model, as defined in [I-D.ietf-ccamp-otn-topo-yang] and
[I-D.ietf-ccamp-otn-tunnel-model].
As defined in Annex M of [ITU-T_G.709], fgOTN is defining a new path
layer network which complements the existing OTN. Therefore:
* A single network topology instance is used to report both OTN and
fgOTN topology information: fgOTN technology-specific attributes
are therefore defined in the fgOTN topology model as augmentations
of the OTN topology model, but without defining a new network type
for fgOTN.
* The OTN tunnel model can be used to setup either an OTN or an
fgOTN tunnel: fgOTN technology-specific attributes are therefore
defined in the fgOTN tunnel model as augmentations of the OTN
tunnel model, which are applicable only when the OTN tunnel is an
fgOTN tunnel.
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4. YANG Data Model for fgOTN Topology
4.1. Fine Grain OTN Topology Data Model Overview
This document aims to describe the data model for fine grain OTN
topology. The YANG module presented in this document augments from
OTN topology data model, i.e., the ietf-otn-topology, as specified in
[I-D.ietf-ccamp-otn-topo-yang]. In section 6 of
[I-D.ietf-ccamp-otn-topo-yang], the guideline for augmenting OTN
topology model was provided, and in this draft, we augment the OTN
topology model to describe the topology characteristics of fgOTN.
Common types, identities and groupings defined in
[I-D.ietf-ccamp-layer1-types] is reused in this document.
[RFC8345] defines an abstract (generic, or base) YANG data model for
network/service topologies and inventories, and provides the
fundamental model for [RFC8795]. OTN topology module in
[I-D.ietf-ccamp-otn-topo-yang] augments from the TE topology YANG
model defined in [RFC8795]. Figure 4 shows the augmentation
relationship.
+--------------+ +-----------------------+
| ietf-network | | ietf-network-topology |
+--------------+ +-----------------------+
^ ^
|_____ _____|
| |
| | Augments
+-------------------+
| ietf-te-topology |
+-------------------+
^
| Augments
|
+-------------------+
| ietf-otn-topology |
+-------------------+
^
| Augments
|
+----------+----------+
| ietf-fgotn-topology |
+---------------------+
Figure 4: Relationship between fgOTN topology and OTN topology model
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The entities, TE attributes and OTN attributes, such as nodes,
termination points and links, are still applicable for describing an
fgOTN topology and the model presented in this document only
specifies technology-specific attributes/information. The fgOTN-
specific attributes including the fgTS, can be used to represent the
bandwidth and label information. At the same time, it is necessary
to extend the encoding and switching-capability enumeration values in
[I-D.ietf-teas-rfc8776-update] to identify that the current Tunnel
Termination Point (TTP) is a termination point of an fgOTN tunnel.
4.2. Bandwidth Augmentation
Based on the OTN topology model, we augment the bandwidth information
of fgOTN, including the max-link-bandwidth and unreserved-bandwidth.
The augmented parameter fgotn-bandwidth is used to indicate how much
of the bandwidth has been allocated for the usage of fgOTN. For
example, if 2 ODU0s are allocated to support fgOTN switching
switching, the fgotn-bandwidth is 2500, and the unit is Mbps.
augment /nw:networks/nw:network/nt:link/tet:te/tet:te-link-attributes
/tet:max-link-bandwidth/tet:te-bandwidth/otnt:otn-bandwidth
/otnt:odulist:
+--rw fgotn-bandwidth? uint16
The augmented fgotnlist structure is used to describe the unreserved
TE bandwidth of fgOTN in the server ODUk. The odu-ts-number is used
to indicate the index of server ODUk channel.
augment /nw:networks/nw:network/nt:link/tet:te/tet:te-link-attributes
/tet:unreserved-bandwidth/tet:te-bandwidth
/otnt:otn-bandwidth:
+--rw fgotnlist* [odu-type odu-ts-number]
+--rw odu-type identityref
+--rw odu-ts-number? uint16
+--rw fgotn-bandwidth? uint16
4.3. Label Augmentation
The model augments the label-restriction list with fgOTN technology-
specific label information using the otn-label-range-info grouping
defined in [I-D.ietf-ccamp-layer1-types].
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augment /nw:networks/tet:te/tet:templates/tet:link-template
/tet:te-link-attributes/tet:label-restrictions
/tet:label-restriction:
+--rw fgts-range* [odu-type odu-ts-number]
+--rw odu-type identityref
+--rw odu-ts-number? uint16
+--rw fgts-reserved? string
+--rw fgts-unreserved? string
The fgts-range list is used to describe the availability of fgOTN
timeslot in the server ODUk, including the fgts-reserved and fgts-
unreserved. The odu-ts-number is used to indicate the index of
server ODUk channel.
5. YANG Data Model for fgOTN Tunnel
5.1. Fine Grain OTN Tunnel Data Model Overview
This document aims to describe the data model for fgOTN tunnel. The
fgOTN tunnel model augments to OTN tunnel
[I-D.ietf-ccamp-otn-tunnel-model] with fgOTN-specific parameters,
including the bandwidth information and label information. Figure 5
shows the augmentation relationship.
+------------------+
| ietf-te |
+------------------+
^
| Augments
|
+-----------------+
| ietf-otn-tunnel |
+-----------------+
^
| Augments
|
+----------+--------+
| ietf-fgotn-tunnel |
+-------------------+
Figure 5: Relationship between fgOTN and OTN tunnel model
It's also worth noting that the fgOTN tunnel provisioning is usually
based on the fgOTN topology. Therefore the fgOTN tunnel model is
usually used together with fgOTN topology model specified in this
document. The OTN tunnel model also imports a few type modules,
including ietf-layer1-types and ietf-te-types.
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A new identity based on odu-type should be defined for fgODUflex in
an updated version of [I-D.ietf-ccamp-layer1-types] to indicate the
bandwidth of fgotn tunnel.
5.2. Bandwidth Augmentation
The model augment TE bandwidth information of fgOTN tunnel.
augment /te:te/te:tunnels/te:tunnel/te:te-bandwidth/te:technology
/otn-tnl:otn/otn-tnl:otn-bandwidth:
+--rw fgoduflex-bandwidth? string
The string value fgoduflex-bandwidth is used to indicate the
bandwidth of this fgOTN tunnel.
5.3. Label Augmentation
The module augments TE label-hop for the explicit route objects
included or excluded by the path computation of the primary-paths and
secondary-paths using the fgts-numbers. The fgts-numbers is used to
specify fgTS information on inter-domain ports of the routing path.
When specifying the fgotn time slot in the routing constraint
information, the ODU time slot must also be specified. We also
augment the TE label-hop for the record route of the LSP using the
fgts-numbers.
6. YANG Data Model for fgOTN types
<CODE BEGINS> file "ietf-fgotn-types@2026-02-27.yang"
module ietf-fgotn-types {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-fgotn-types";
prefix fgotn-types;
import ietf-layer1-types {
prefix l1-types;
reference
"This module defines Layer 1 YANG types.";
}
/* Note: The RFC Editor will replace YYYY with the number assigned
to the RFC once draft-ietf-ccamp-layer1-types becomes an RFC.*/
organization
"Internet Engineering Task Force (IETF) CCAMP WG";
contact
"
ID-draft editor:
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Yanxia Tan (tanyx11@chinaunicom.cn);
Yanlei Zheng (zhengyanlei@chinaunicom.cn);
Italo Busi (italo.busi@huawei.com);
Chaode Yu (yuchaode@huawei.com);
Xing Zhao (zhaoxing@caict.ac.cn);
";
description
"This module contains a collection of YANG data types considered
generally useful for fine grain Optical Transport Network
(fgOTN) networks.
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; see
the RFC itself for full legal notices.";
// RFC Ed.: replace XXXX with actual RFC number and remove this
// note.
// RFC Ed.: update the date below with the date of RFC publication
// and remove this note.
revision 2026-02-27 {
description
"initial version";
reference
"RFC XXXX: YANG Data Models for fine grain Optical Transport
Network";
}
identity fgODUflex {
base l1-types:odu-type;
description
"fgODUflex type (fine grain flexible bit rate, resizable).";
}
}
<CODE ENDS>
Figure 6: fgOTN types YANG module
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7. YANG Tree for fgOTN topology
Figure 7 below shows the tree diagram of the YANG data model defined
in module "ietf-fgotn-topology" (Figure 8).
module: ietf-fgotn-topology
augment /nw:networks/nw:network/nt:link/tet:te
/tet:te-link-attributes/tet:max-link-bandwidth
/tet:te-bandwidth/otnt:otn-bandwidth/otnt:odulist:
+--rw fgotn-bandwidth? uint16
augment /nw:networks/nw:network/nt:link/tet:te
/tet:te-link-attributes/tet:unreserved-bandwidth
/tet:te-bandwidth/otnt:otn-bandwidth/otnt:odulist:
+--rw fgotn-bandwidth? uint16
augment /nw:networks/nw:network/nt:link/tet:te
/tet:te-link-attributes/tet:unreserved-bandwidth
/tet:te-bandwidth/otnt:otn-bandwidth:
+--rw fgotnlist* [odu-type odu-ts-number]
+--rw odu-type identityref
+--rw odu-ts-number fgotnt:ts-list
+--rw fgotn-bandwidth? uint16
augment /nw:networks/nw:network/nt:link/tet:te
/tet:te-link-attributes/tet:label-restrictions
/tet:label-restriction:
+--rw fgts-range* [odu-type odu-ts-number]
+--rw odu-type identityref
+--rw odu-ts-number fgotnt:ts-list
+--rw fgts-reserved? fgotnt:ts-list
+--rw fgts-unreserved? fgotnt:ts-list
Figure 7
8. YANG Data Model for fgOTN topology
<CODE BEGINS> file "ietf-fgotn-topology@2026-02-27.yang"
module ietf-fgotn-topology {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-fgotn-topology";
prefix fgotnt;
import ietf-network {
prefix nw;
reference
"RFC8345: A YANG Data Model for Network Topologies";
}
import ietf-network-topology {
prefix nt;
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reference
"RFC8345: A YANG Data Model for Network Topologies";
}
import ietf-te-topology {
prefix tet;
reference
"RFC 8795: YANG Data Model for Traffic Engineering (TE)
Topologies";
}
import ietf-layer1-types {
prefix l1-types;
reference
"RFC YYYY: A YANG Data Model for Layer 1 Types";
}
import ietf-fgotn-types {
prefix fgotn-types;
reference
"RFC XXXX: YANG Data Models for fine grain Optical Transport
Network";
}
/* Note: The RFC Editor will replace YYYY with the number assigned
to the RFC once draft-ietf-ccamp-layer1-types becomes an RFC.*/
import ietf-otn-topology {
prefix otnt;
reference
"RFC ZZZZ: A YANG Data Model for Optical Transport Network
Topology";
}
/* Note: The RFC Editor will replace ZZZZ with the number assigned
to the RFC once draft-ietf-ccamp-otn-topo-yang becomes an RFC.*/
organization
"Internet Engineering Task Force (IETF) CCAMP WG";
contact
"
ID-draft editor:
Yanxia Tan (tanyx11@chinaunicom.cn);
Yanlei Zheng (zhengyanlei@chinaunicom.cn);
Italo Busi (italo.busi@huawei.com);
Chaode Yu (yuchaode@huawei.com);
Xing Zhao (zhaoxing@caict.ac.cn);
";
description
"This module defines a YANG data model for fgOTN-specific
extension based on existing network topology models. The model
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fully conforms to the Network Management Datastore Architecture
(NMDA).
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; 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.";
// RFC Ed.: replace XXXX with actual RFC number and remove this
// note.
// RFC Ed.: update the date below with the date of RFC publication
// and remove this note.
revision 2026-02-27 {
description
"initial version";
reference
"RFC XXXX: YANG Data Models for fine grain Optical Transport
Network";
}
typedef ts-list {
type string {
pattern '([1-9][0-9]{0,3}(-[1-9][0-9]{0,3})?'
+ '(,[1-9][0-9]{0,3}(-[1-9][0-9]{0,3})?)*)?';
}
description
"A list of Tributary Slots (TS) ranging between 1 and 4095.
If multiple values or ranges are given, they all MUST be
disjoint and MUST be in ascending order.
For example 1-20,25,50-1000.";
reference
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"RFC 7139: GMPLS Signaling Extensions for Control
of Evolving G.709 Optical Transport Networks";
}
augment "/nw:networks/nw:network/nt:link/tet:te"
+ "/tet:te-link-attributes/tet:max-link-bandwidth"
+ "/tet:te-bandwidth/otnt:otn-bandwidth/otnt:odulist" {
description
"specific augmentation of fgOTN link on maximum link
bandwidth";
leaf fgotn-bandwidth {
when 'derived-from-or-self(../otnt:odu-type,'
+ '"fgotn-types:fgODUflex")' {
description
"Applicable when odu-type is fgODUflex.";
}
type uint16;
units "megabits per second";
description
"It is used to indicate how much of the bandwidth has been
allocated for the usage of fgOTN.";
}
}
augment "/nw:networks/nw:network/nt:link/tet:te"
+ "/tet:te-link-attributes/tet:unreserved-bandwidth"
+ "/tet:te-bandwidth/otnt:otn-bandwidth/otnt:odulist" {
description
"specific augmentation of fgOTN link on unreserved link
bandwidth";
leaf fgotn-bandwidth {
when 'derived-from-or-self(../otnt:odu-type,'
+ '"fgotn-types:fgODUflex")' {
description
"Applicable when odu-type is fgODUflex.";
}
type uint16;
units "megabits per second";
description
"The unreserved bandwidth of fgOTN before the server ODUk
is set up";
}
}
augment "/nw:networks/nw:network/nt:link/tet:te"
+ "/tet:te-link-attributes/tet:unreserved-bandwidth"
+ "/tet:te-bandwidth/otnt:otn-bandwidth" {
description
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"specific augmentation of fgOTN link on unreserved link
bandwidth";
list fgotnlist {
key "odu-type odu-ts-number";
description
"This structure is used to describe the unsreserved
bandwidth of fgOTN in the server ODUk";
leaf odu-type {
type identityref {
base l1-types:odu-type;
}
description
"The granularity of server ODUk";
}
leaf odu-ts-number {
type fgotnt:ts-list;
description
"The index of server ODUk channel";
}
leaf fgotn-bandwidth {
type uint16;
units "megabits per second";
description
"The unreserved bandwidth of fgOTN in this server ODUk";
}
}
}
augment "/nw:networks/nw:network/nt:link/tet:te"
+ "/tet:te-link-attributes/tet:label-restrictions"
+ "/tet:label-restriction" {
description
"specific augmentation of fgOTN label";
list fgts-range {
key "odu-type odu-ts-number";
description
"This structure is used to describe the availability of
fgOTN timeslot in the server ODUk";
leaf odu-type {
type identityref {
base l1-types:odu-type;
}
description
"The granularity of server ODUk";
}
leaf odu-ts-number {
type fgotnt:ts-list;
description
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"The index of server ODUk channel";
}
leaf fgts-reserved {
type fgotnt:ts-list;
description
"The reserved fgOTN timeslot in this server ODUk";
}
leaf fgts-unreserved {
type fgotnt:ts-list;
description
"The unreserved fgOTN timeslot in this server ODUk";
}
}
}
}
<CODE ENDS>
Figure 8: fgOTN topology YANG module
9. YANG Tree for fgOTN tunnel
Figure 9 below shows the tree diagram of the YANG data model defined
in module "ietf-fgotn-tunnel" (Figure 10).
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module: ietf-fgotn-tunnel
augment /te:te/te:tunnels/te:tunnel/te:te-bandwidth/te:technology
/otn-tnl:otn/otn-tnl:otn-bandwidth:
+--rw fgoduflex-bandwidth? string
augment /te:te/te:tunnels/te:tunnel/te:primary-paths
/te:primary-path/te:explicit-route-objects
/te:route-object-include-exclude/te:type/te:label
/te:label-hop/te:te-label/te:technology/otn-tnl:otn
/otn-tnl:otn-label:
+--rw fgts-numbers? string
augment /te:te/te:tunnels/te:tunnel/te:primary-paths
/te:primary-path/te:primary-reverse-path
/te:explicit-route-objects
/te:route-object-include-exclude/te:type/te:label
/te:label-hop/te:te-label/te:technology/otn-tnl:otn
/otn-tnl:otn-label:
+--rw fgts-numbers? string
augment /te:te/te:tunnels/te:tunnel/te:secondary-paths
/te:secondary-path/te:explicit-route-objects
/te:route-object-include-exclude/te:type/te:label
/te:label-hop/te:te-label/te:technology/otn-tnl:otn
/otn-tnl:otn-label:
+--rw fgts-numbers? string
augment /te:te/te:tunnels/te:tunnel/te:secondary-reverse-paths
/te:secondary-reverse-path/te:explicit-route-objects
/te:route-object-include-exclude/te:type/te:label
/te:label-hop/te:te-label/te:technology/otn-tnl:otn
/otn-tnl:otn-label:
+--rw fgts-numbers? string
augment /te:te/te:lsps/te:lsp/te:lsp-actual-route-information
/te:lsp-actual-route-information/te:type/te:label
/te:label-hop/te:te-label/te:technology/otn-tnl:otn
/otn-tnl:otn-label:
+--ro fgts-numbers? string
Figure 9
10. YANG Data Model for fgOTN tunnel
<CODE BEGINS> file "ietf-fgotn-tunnel@2026-02-27.yang"
module ietf-fgotn-tunnel {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-fgotn-tunnel";
prefix fgotn-tnl;
import ietf-te {
prefix te;
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reference
"RFC KKKK: A YANG Data Model for Traffic Engineering Tunnels,
Label Switched Paths and Interfaces";
}
import ietf-fgotn-types {
prefix fgotn-types;
reference
"RFC XXXX: YANG Data Models for fine grain Optical Transport
Network";
}
/* Note: The RFC Editor will replace KKKK with the number assigned
to the RFC once draft-ietf-teas-yang-te becomes an RFC.*/
import ietf-otn-tunnel {
prefix otn-tnl;
reference
"RFC JJJJ: OTN Tunnel YANG Model";
}
/* Note: The RFC Editor will replace JJJJ with the number assigned
to the RFC once draft-ietf-ccamp-otn-tunnel-model becomes
an RFC.*/
organization
"Internet Engineering Task Force (IETF) CCAMP WG";
contact
"
ID-draft editor:
Yanxia Tan (tanyx11@chinaunicom.cn);
Yanlei Zheng (zhengyanlei@chinaunicom.cn);
Italo Busi (italo.busi@huawei.com);
Chaode Yu (yuchaode@huawei.com);
Xing Zhao (zhaoxing@caict.ac.cn);
";
description
"This module defines a YANG data model for fgOTN-specific
extension based on existing network topology models. The model
fully conforms to the Network Management Datastore Architecture
(NMDA).
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
Tan, et al. Expires 2 September 2026 [Page 22]
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Relating to IETF Documents
(https://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC XXXX; see
the RFC itself for full legal notices.";
// RFC Ed.: replace XXXX with actual RFC number and remove this
// note.
// RFC Ed.: update the date below with the date of RFC publication
// and remove this note.
revision 2026-02-27 {
description
"initial version";
reference
"RFC XXXX: YANG Data Models for fine grain Optical Transport
Network";
}
augment "/te:te/te:tunnels/te:tunnel/"
+ "te:te-bandwidth/te:technology/"
+ "otn-tnl:otn/otn-tnl:otn-bandwidth" {
description
"augmentation of fgOTN tunnel on bandwidth structure";
leaf fgoduflex-bandwidth {
when 'derived-from-or-self(../otn-tnl:odu-type,'
+ '"fgotn-types:fgODUflex")' {
description
"Applicable when odu-type is fgODUflex.";
}
type string;
description
"Augment TE bandwidth of the fgOTN tunnel";
}
}
augment "/te:te/te:tunnels/te:tunnel/"
+ "te:primary-paths/te:primary-path/"
+ "te:explicit-route-objects/"
+ "te:route-object-include-exclude/te:type/te:label/"
+ "te:label-hop/te:te-label/te:technology/otn-tnl:otn"
+ "/otn-tnl:otn-label" {
description
"augmentation of fgOTN label";
leaf fgts-numbers {
type string;
description
"Augment fgOTN timeslot information of this label hop";
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}
}
augment "/te:te/te:tunnels/te:tunnel/te:primary-paths"
+ "/te:primary-path/te:primary-reverse-path"
+ "/te:explicit-route-objects"
+ "/te:route-object-include-exclude/te:type/te:label"
+ "/te:label-hop/te:te-label/te:technology/otn-tnl:otn"
+ "/otn-tnl:otn-label" {
description
"augmentation of fgOTN label";
leaf fgts-numbers {
type string;
description
"Augment fgOTN timeslot information of this label hop";
}
}
augment "/te:te/te:tunnels/te:tunnel/te:secondary-paths"
+ "/te:secondary-path/te:explicit-route-objects"
+ "/te:route-object-include-exclude/te:type/te:label"
+ "/te:label-hop/te:te-label/te:technology/otn-tnl:otn"
+ "/otn-tnl:otn-label" {
description
"augmentation of fgOTN label";
leaf fgts-numbers {
type string;
description
"fgOTN timeslot information of this label hop";
}
}
augment "/te:te/te:tunnels/te:tunnel/te:secondary-reverse-paths"
+ "/te:secondary-reverse-path/te:explicit-route-objects"
+ "/te:route-object-include-exclude/te:type/te:label"
+ "/te:label-hop/te:te-label/te:technology/otn-tnl:otn"
+ "/otn-tnl:otn-label" {
description
"augmentation of fgOTN label";
leaf fgts-numbers {
type string;
description
"fgOTN timeslot information of this label hop";
}
}
augment "/te:te/te:lsps/te:lsp/te:lsp-actual-route-information"
+ "/te:lsp-actual-route-information/te:type/te:label"
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+ "/te:label-hop/te:te-label/te:technology/otn-tnl:otn"
+ "/otn-tnl:otn-label" {
description
"augmentation of fgOTN label";
leaf fgts-numbers {
type string;
description
"fgOTN timeslot information of this label hop";
}
}
}
<CODE ENDS>
Figure 10: fgOTN tunnel YANG module
11. Manageability Considerations
<Add any manageability considerations>
12. Security Considerations
<Add any security considerations>
13. IANA Considerations
<Add any IANA considerations>
14. References
14.1. Normative References
[I-D.ietf-ccamp-layer1-types]
Zheng, H. and I. Busi, "Common YANG Data Types for Layer 1
Networks", Work in Progress, Internet-Draft, draft-ietf-
ccamp-layer1-types-18, 23 February 2024,
<https://datatracker.ietf.org/doc/html/draft-ietf-ccamp-
layer1-types-18>.
[I-D.ietf-ccamp-otn-topo-yang]
Zheng, H., Busi, I., Liu, X., Belotti, S., and O. G. de
Dios, "A YANG Data Model for Optical Transport Network
Topology", Work in Progress, Internet-Draft, draft-ietf-
ccamp-otn-topo-yang-20, 7 November 2024,
<https://datatracker.ietf.org/doc/html/draft-ietf-ccamp-
otn-topo-yang-20>.
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[I-D.ietf-ccamp-otn-tunnel-model]
Zheng, H., Busi, I., Belotti, S., Lopez, V., and Y. Xu, "A
YANG Data Model for Optical Transport Network (OTN)
Tunnels and Label Switched Paths", Work in Progress,
Internet-Draft, draft-ietf-ccamp-otn-tunnel-model-24, 1
December 2025, <https://datatracker.ietf.org/doc/html/
draft-ietf-ccamp-otn-tunnel-model-24>.
[I-D.ietf-teas-yang-te]
Saad, T., Gandhi, R., Liu, X., Beeram, V. P., and I.
Bryskin, "A YANG Data Model for Traffic Engineering
Tunnels, Label Switched Paths, and Interfaces", Work in
Progress, Internet-Draft, draft-ietf-teas-yang-te-43, 28
February 2026, <https://datatracker.ietf.org/doc/html/
draft-ietf-teas-yang-te-43>.
[ITU-T_G.709]
International Telecommunication Union, "Interfaces for the
optical transport network", ITU-T Recommendation G.709,
Amendment 3 , March 2024,
<https://www.itu.int/rec/T-REC-G.709/>.
[ITU-T_G.709.20]
International Telecommunication Union, "Overview of fine
grain OTN", ITU-T Recommendation G.709.20, Amendment 1 ,
May 2025, <https://www.itu.int/rec/T-REC-G.709.20/>.
[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/rfc/rfc2119>.
[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/rfc/rfc6241>.
[RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
RFC 7950, DOI 10.17487/RFC7950, August 2016,
<https://www.rfc-editor.org/rfc/rfc7950>.
[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/rfc/rfc8174>.
[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/rfc/rfc8340>.
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[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/rfc/rfc8342>.
14.2. Informative References
[I-D.ietf-teas-rfc8776-update]
Busi, I., Guo, A., Liu, X., Saad, T., and I. Bryskin,
"Common YANG Data Types for Traffic Engineering", Work in
Progress, Internet-Draft, draft-ietf-teas-rfc8776-update-
22, 18 February 2026,
<https://datatracker.ietf.org/doc/html/draft-ietf-teas-
rfc8776-update-22>.
[RFC8345] Clemm, A., Medved, J., Varga, R., Bahadur, N.,
Ananthakrishnan, H., and X. Liu, "A YANG Data Model for
Network Topologies", RFC 8345, DOI 10.17487/RFC8345, March
2018, <https://www.rfc-editor.org/rfc/rfc8345>.
[RFC8795] Liu, X., Bryskin, I., Beeram, V., Saad, T., Shah, H., and
O. Gonzalez de Dios, "YANG Data Model for Traffic
Engineering (TE) Topologies", RFC 8795,
DOI 10.17487/RFC8795, August 2020,
<https://www.rfc-editor.org/rfc/rfc8795>.
Appendix A. Multi-domain fgOTN Hitless Resizing Process
The process of multi-domain fgOTN hitless resizing include five
steps. The source controller alone report the hitless bandwidth
adjustment status to the MDSC coordinator. To be noted that, the
resizing process is divided into two directions, and the resizing is
considered successful when both directions have been adjusted.
Step 1: The MDSC coordinator sends an resizing command to the source
node (Node1) via Controller 1.
Step 2: Controller 1 will report a bandwidth adjustment starting
status notification, e.g. ietf-te-types:lsp-bandwidth-modifying, to
the MDSC.
Step 3: Node 1 to node 6 will modify their configuration in the
forward direction through data plane node by node. The detail of
this process can reference to Annex O.2 of [ITU-T_G.709].
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Step 4: At the same time, the reverse direction bandwidth resizing
will be triggered auotmatically by the data plane in node 6.
Controller 3 needs to report an bandwidth adjustment starting status
notification, ietf-te-types:lsp-bandwidth-modifying, to the MDSC.
Step 5: After the reverse direction (Node 6 to Node 1) resizing is
completed, Controller 1 will report an ending status notification,
ietf-te-types:lsp-bandwidth-modified-ok, to the MDSC.
If the hitless resizing fails, the source controller (i.e.,
Controller 1) needs to report an bandwidth adjustment failure status
notification, ietf-te-types:lsp-bandwidth-modify-failed, to the MDSC
coordinator.
During the whole process, all domain controllers, including the
intermediate domain Controller 2, need to report the notifications of
topology and tunnel resource changes to the MDSC.
Acknowledgments
Contributors
Zelin Wang
China Unicom
Beijing
China
Email: wangzl172@chinaunicom.cn
Chen Li
Fiberhome Telecommunication Technologies Co.,LTD
Email: lich@fiberhome.com
Authors' Addresses
Yanxia Tan
China Unicom
Beijing
China
Email: tanyx11@chinaunicom.cn
Yanlei Zheng
China Unicom
Beijing
China
Email: zhengyanlei@chinaunicom.cn
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Italo Busi
Huawei Technologies
Email: italo.busi@huawei.com
Chaode Yu
Huawei Technologies
China
Email: yuchaode@huawei.com
Xing Zhao
CAICT
China
Email: zhaoxing@caict.ac.cn
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