Common Control and Measurement Plane Y. Tan Internet-Draft Y. Zheng Intended status: Standards Track China Unicom Expires: 4 January 2026 I. Busi C. Yu Huawei Technologies X. Zhao CAICT 3 July 2025 YANG Data Models for fine grain Optical Transport Network draft-tan-ccamp-fgotn-yang-04 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. Tan, et al. Expires 4 January 2026 [Page 1] Internet-Draft Fine grain OTN YANG July 2025 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 4 January 2026. Copyright Notice Copyright (c) 2025 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/ license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include 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. 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 . . . . . . . . . . . . . 9 4.1. Fine Grain OTN Topology Data Model Overview . . . . . . . 9 4.2. Bandwidth Augmentation . . . . . . . . . . . . . . . . . 11 4.3. Label Augmentation . . . . . . . . . . . . . . . . . . . 11 5. YANG Data Model for fgOTN Tunnel . . . . . . . . . . . . . . 11 5.1. Fine Grain OTN Tunnel Data Model Overview . . . . . . . . 12 5.2. Bandwidth Augmentation . . . . . . . . . . . . . . . . . 12 Tan, et al. Expires 4 January 2026 [Page 2] Internet-Draft Fine grain OTN YANG July 2025 5.3. Label Augmentation . . . . . . . . . . . . . . . . . . . 13 6. YANG Tree for fgOTN topology . . . . . . . . . . . . . . . . 13 7. YANG Data Model for fgOTN topology . . . . . . . . . . . . . 13 8. YANG Tree for fgOTN tunnel . . . . . . . . . . . . . . . . . 17 9. YANG Data Model for fgOTN tunnel . . . . . . . . . . . . . . 18 10. Manageability Considerations . . . . . . . . . . . . . . . . 22 11. Security Considerations . . . . . . . . . . . . . . . . . . . 22 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 22 13. References . . . . . . . . . . . . . . . . . . . . . . . . . 22 13.1. Normative References . . . . . . . . . . . . . . . . . . 22 13.2. Informative References . . . . . . . . . . . . . . . . . 23 Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . 24 Appendix B. Appendix A. Multi-domain fgOTN Hitless Resizing Process . . . . . . . . . . . . . . . . . . . . . . . . . 24 Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 24 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 25 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]. Tan, et al. Expires 4 January 2026 [Page 3] Internet-Draft Fine grain OTN YANG July 2025 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 6 of this document. The meaning of the symbols in this diagram is defined in [RFC8340]. Tan, et al. Expires 4 January 2026 [Page 4] Internet-Draft Fine grain OTN YANG July 2025 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]. Tan, et al. Expires 4 January 2026 [Page 5] Internet-Draft Fine grain OTN YANG July 2025 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. Tan, et al. Expires 4 January 2026 [Page 6] Internet-Draft Fine grain OTN YANG July 2025 +-----+ | 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. Tan, et al. Expires 4 January 2026 [Page 7] Internet-Draft Fine grain OTN YANG July 2025 +-----+ +-----+ ----| 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 multi-domain hitless resizing scenario, both the source controller and the destination controller should report the bandwidth adjustment status to the MDSC coordinator upon completion. Tan, et al. Expires 4 January 2026 [Page 8] Internet-Draft Fine grain OTN YANG July 2025 +----------+ ----------------------| 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. The attributes related to fgOTN are augments from OTN topology data model, and fgOTN topology is not treated as a separate hierarchy. The fgOTN tunnel is defined as a separate tunnel hierarchy, and the fgOTN tunnels need to be pre-set and created before the service provisioning process. 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. Tan, et al. Expires 4 January 2026 [Page 9] Internet-Draft Fine grain OTN YANG July 2025 [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 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. Tan, et al. Expires 4 January 2026 [Page 10] Internet-Draft Fine grain OTN YANG July 2025 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]. augment /nw:networks/tet:te/tet:templates/tet:link-template /tet:te-link-attributes/tet:label-restrictions /tet:label-restriction/otnt:otn-label-range: +--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 Tan, et al. Expires 4 January 2026 [Page 11] Internet-Draft Fine grain OTN YANG July 2025 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. 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: +--rw fgoduflex-bandwidth? string The string value fgoduflex-bandwidth is used to indicate the bandwidth of this fgOTN tunnel. Tan, et al. Expires 4 January 2026 [Page 12] Internet-Draft Fine grain OTN YANG July 2025 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 Tree for fgOTN topology Figure 6 below shows the tree diagram of the YANG data model defined in module "ietf-fgotn-topology" (Figure 7). 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: +--rw fgotnlist* [odu-type odu-ts-number] +--rw odu-type identityref +--rw odu-ts-number uint16 +--rw fgotn-bandwidth? uint16 augment /nw:networks/tet:te/tet:templates/tet:link-template /tet:te-link-attributes/tet:label-restrictions /tet:label-restriction/otnt:otn-label-range: +--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 Figure 6 7. YANG Data Model for fgOTN topology file "ietf-fgotn-topology@2025-06-18.yang" module ietf-fgotn-topology { /* TODO: FIXME */ yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:ietf-fgotn-topology"; Tan, et al. Expires 4 January 2026 [Page 13] Internet-Draft Fine grain OTN YANG July 2025 prefix "fgotnt"; import ietf-network { prefix "nw"; reference "RFC8345: A YANG Data Model for Network Topologies"; } import ietf-network-topology { prefix "nt"; 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"; } /* 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); Tan, et al. Expires 4 January 2026 [Page 14] Internet-Draft Fine grain OTN YANG July 2025 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) 2024 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 2025-06-18 { description "initial version"; reference "RFC XXXX: YANG Data Models for fine grain Optical Transport Network"; } 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 { type uint16; description "It is used to indicate how much of the bandwidth has been allocated for the usage of fgOTN."; } Tan, et al. Expires 4 January 2026 [Page 15] Internet-Draft Fine grain OTN YANG July 2025 } augment "/nw:networks/nw:network/nt:link/tet:te" + "/tet:te-link-attributes/tet:unreserved-bandwidth" + "/tet:te-bandwidth/otnt:otn-bandwidth" { description "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 uint16; description "The index of server ODUk channel"; } leaf fgotn-bandwidth { type uint16; description "The unsreserved bandwidth of fgOTN in this server ODUk"; } } } augment "/nw:networks/tet:te/tet:templates/tet:link-template"+ "/tet:te-link-attributes/tet:label-restrictions" + "/tet:label-restriction/otnt:otn-label-range" { 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; Tan, et al. Expires 4 January 2026 [Page 16] Internet-Draft Fine grain OTN YANG July 2025 } description "The granularity of server ODUk"; } leaf odu-ts-number { type uint16; description "The index of server ODUk channel"; } leaf fgts-reserved { type string; description "The reserved fgOTN timeslot in this server ODUk"; } leaf fgts-unreserved { type string; description "The unreserved fgOTN timeslot in this server ODUk"; } } } } Figure 7: fgOTN topology YANG module 8. YANG Tree for fgOTN tunnel Figure 8 below shows the tree diagram of the YANG data model defined in module "ietf-fgotn-tunnel" (Figure 9). Tan, et al. Expires 4 January 2026 [Page 17] Internet-Draft Fine grain OTN YANG July 2025 module: ietf-fgotn-tunnel augment /te:te/te:tunnels/te:tunnel/te:te-bandwidth/te:technology /otn-tnl:otn: +--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 8 9. YANG Data Model for fgOTN tunnel file "ietf-fgotn-tunnel@2025-06-18.yang" module ietf-fgotn-tunnel { /* TODO: FIXME */ yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:ietf-fgotn-tunnel"; prefix "fgotn-tnl"; Tan, et al. Expires 4 January 2026 [Page 18] Internet-Draft Fine grain OTN YANG July 2025 import ietf-te { prefix "te"; reference "RFC KKKK: A YANG Data Model for Traffic Engineering Tunnels, Label Switched Paths and Interfaces"; } /* 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) 2024 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 Tan, et al. Expires 4 January 2026 [Page 19] Internet-Draft Fine grain OTN YANG July 2025 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 2025-06-18 { 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" { description "augmentation of fgOTN tunnel on bandwidth structure"; leaf fgoduflex-bandwidth { 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"; } } 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 Tan, et al. Expires 4 January 2026 [Page 20] Internet-Draft Fine grain OTN YANG July 2025 "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" + "/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"; } } Tan, et al. Expires 4 January 2026 [Page 21] Internet-Draft Fine grain OTN YANG July 2025 } Figure 9: fgOTN tunnel YANG module 10. Manageability Considerations 11. Security Considerations 12. IANA Considerations 13. References 13.1. 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, . [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, . [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-23, 4 June 2025, . [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 Tan, et al. Expires 4 January 2026 [Page 22] Internet-Draft Fine grain OTN YANG July 2025 Progress, Internet-Draft, draft-ietf-teas-yang-te-38, 29 May 2025, . [ITU-T_G.709] International Telecommunication Union, "Interfaces for the optical transport network", ITU-T Recommendation G.709, Amendment 3 , March 2024, . [ITU-T_G.709.20] International Telecommunication Union, "Overview of fine grain OTN", ITU-T Recommendation G.709.20, Amendment 1 , May 2025, . [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [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, . [RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language", RFC 7950, DOI 10.17487/RFC7950, August 2016, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . [RFC8340] Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams", BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018, . [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, . 13.2. 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- Tan, et al. Expires 4 January 2026 [Page 23] Internet-Draft Fine grain OTN YANG July 2025 17, 21 February 2025, . [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, . [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, . Appendix A. Acknowledgments Appendix B. Appendix A. Multi-domain fgOTN Hitless Resizing Process The process of cross domain hitless resizing include six steps. Both the source and destination controllers should report the hitless bandwidth adjustment status to the MDSC coordinator. Step 1: The MDSC coordinator sends an resizing command to the source node (Node1) via Controller 1. The command includes the target bandwidth and the fgODUflex service identifier. Step 2: Controller 1 reports the bandwidth adjustment status ietf-te- types:lsp-path-modifying to the MDSC via notification. Step 3: After the resizing in the direction from Node1 to Node6 was completed, Controller 1 reported ietf-te-types:lsp-path-modified to MDSC. This automatically triggered a reverse-direction resizing (Node6 to Node1). Step 4: Once the reverse resizing begins, Controller 3 reports the bandwidth adjustment status to the MDSC via notification. Step 5: After the reverse direction (Node 6 to Node 1) resizing is completed, Controller 3 reports ietf-te-types:lsp-path-modified to MDSC. Step 6: All domain controllers, including the intermediate domain Controller 2, report notifications of topology and tunnel resource changes to MDSC coordinator. Contributors Tan, et al. Expires 4 January 2026 [Page 24] Internet-Draft Fine grain OTN YANG July 2025 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 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 Tan, et al. Expires 4 January 2026 [Page 25]