A YANG Data Model for L1 Connectivity Service Model (L1CSM)
draft-ietf-ccamp-l1csm-yang-21
The information below is for an old version of the document.
Document | Type |
This is an older version of an Internet-Draft whose latest revision state is "Active".
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Authors | Young Lee , Kwang-koog Lee , Haomian Zheng , Oscar Gonzalez de Dios , Daniele Ceccarelli | ||
Last updated | 2023-03-27 (Latest revision 2023-02-02) | ||
Replaces | draft-fioccola-ccamp-l1csm-yang | ||
RFC stream | Internet Engineering Task Force (IETF) | ||
Formats | |||
Reviews |
YANGDOCTORS Last Call review
(of
-15)
by Joe Clarke
Ready w/nits
YANGDOCTORS Early review
(of
-07)
by Robert Wilton
On the right track
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Additional resources | Mailing list discussion | ||
Stream | WG state | WG Consensus: Waiting for Write-Up | |
Associated WG milestone |
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Document shepherd | Luis M. Contreras | ||
IESG | IESG state | I-D Exists | |
Consensus boilerplate | Yes | ||
Telechat date | (None) | ||
Responsible AD | (None) | ||
Send notices to | luismiguel.contrerasmurillo@telefonica.com |
draft-ietf-ccamp-l1csm-yang-21
CCAMP Working Group Y. Lee Internet-Draft Samsung Intended status: Standards Track K. Lee Expires: 6 August 2023 Korea Telecom H. Zheng Huawei Technologies O. Gonzalez de Dios Telefonica D. Ceccarelli Cisco 2 February 2023 A YANG Data Model for L1 Connectivity Service Model (L1CSM) draft-ietf-ccamp-l1csm-yang-21 Abstract This document provides a YANG Layer 1 Connectivity Service Model (L1CSM). This model can be utilized by a customer network controller to initiate a connectivity service request as well as to retrieve service states for a Layer 1 network controller communicating with its customer network controller. This YANG model is NMDA-compliant. 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 6 August 2023. Copyright Notice Copyright (c) 2023 IETF Trust and the persons identified as the document authors. All rights reserved. Lee, et al. Expires 6 August 2023 [Page 1] Internet-Draft A YANG Data Model for L1CSM February 2023 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 . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Deployment Scenarios . . . . . . . . . . . . . . . . . . 3 1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 6 1.3. Tree Diagram . . . . . . . . . . . . . . . . . . . . . . 6 1.4. Prefixes in Data Node Names . . . . . . . . . . . . . . . 7 1.5. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 7 2. L1CSM YANG Model Overview . . . . . . . . . . . . . . . . . . 7 3. L1CSM YANG Model (Tree Structure) . . . . . . . . . . . . . . 8 4. L1CSM YANG Code . . . . . . . . . . . . . . . . . . . . . . . 9 5. Security Considerations . . . . . . . . . . . . . . . . . . . 13 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 15 8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 15 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 15 9.1. Normative References . . . . . . . . . . . . . . . . . . 15 9.2. Informative References . . . . . . . . . . . . . . . . . 16 Appendix A. JSON Example . . . . . . . . . . . . . . . . . . . . 16 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17 1. Introduction This document provides a YANG Layer 1 (L1) Connectivity Service Model (L1CSM) which can be classified as Network Service YANG module per [RFC8199]. This model can be utilized by a customer network controller to initiate a connectivity service request as well as to retrieve service states for a Layer 1 network controller communicating with its customer network controller via a NETCONF [RFC8341] or a RESTCONF [RFC8040] interface. [RFC4847] provides a framework and service level requirements for Layer 1 Virtual Private Networks (L1VPNs). It classifies the provision of L1VPN services into three service models (not to be confused with YANG models): the management-based service model, the signaling-based service model (Basic Mode), and the signaling and routing service model (Enhanced Mode). Lee, et al. Expires 6 August 2023 [Page 2] Internet-Draft A YANG Data Model for L1CSM February 2023 In the management-based service model, customer management systems and provider management systems communicate with each other. Customer management systems access provider management systems to request Layer 1 connection setup/deletion between a pair of CEs. Customer management systems may obtain additional information, such as resource availability information and monitoring information, from provider management systems. There is no control message exchange between a CE and PE. In the signaling-based service model (Basic Model), the CE-PE interface's functional repertoire is limited to path setup signaling only. In the signaling and routing service model (Enhanced Mode), the CE-PE interface provides the signaling capabilities as in the Basic Mode, plus permits limited exchange of information between the control planes of the provider and the customer to help such functions as discovery of customer network routing information (i.e., reachability or TE information in remote customer sites), or parameters of the part of the provider's network dedicated to the customer. The primary focus of this document is to describe L1CSM YANG model required for the instantiation of point-to-point L1 connectivity services, to provide Layer 1 connectivity between two or more customer sites where the customer has some control over the establishment and type of the connectivity. The L1CSM specified in this document supports the point-to-point connectivity services defined in [RFC4847]. The YANG data model defined in Section 3 is consistent with the Service Attributes defined in [MEF63], with the exception of the Service Level Specification Service Attributes which are ouside the scope of this document. This YANG model is NMDA-compliant. 1.1. Deployment Scenarios Figure 1 depicts a deployment scenario of the L1CSM SDN control-based service model for an external customer instantiating L1 point-to- point connectivity to the provider. Lee, et al. Expires 6 August 2023 [Page 3] Internet-Draft A YANG Data Model for L1CSM February 2023 +------------+ | Customer | | Service | |Orchestrator| +------------+ | .. .. .. .. ..|.. .. .. .. .. .. : | : : +--------------------+ : : | | : : | +----------+ | : : | | Network | | : : | | SDN | | : : | |Controller| | : : | |/NMS/EMS | | : : | +----------+ | : : | | : : | | : +----+ : +----+ +----+ : +----+ | CE |----:---| PE |..............| PE |---:---| CE | +----+ : +----+ +----+ : +----+ : | | : : | | : : +--------------------+ : : | | : : |<-Provider network->| : Customer Customer Interface Interface Figure 1: L1CSM SDN Controller/EMS/NMS-Based Service Model: External Customer With this scenario, the customer service orchestrator interfaces with the network SDN controller of the provider using a Customer Service Model as defined in [RFC8309]. Figure 2 depicts another deployment scenario for internal customer (e.g., higher-layer service management departments) interfacing the Layer 1 transport network department. With this scenario, a multi- service backbone is characterized such that each service department of a provider (e.g., L2/3 services) that receives the same provider's L1CSM service provides a different kind of higher-layer service. The customer receiving the L1CSM service (i.e., each service department) can offer its own services, whose payloads can be any layer (e.g., ATM, IP, TDM). The Layer 1 transport network and each service network belong to the same organization, but may be managed separately. The Service SDN Controller is the control/management Lee, et al. Expires 6 August 2023 [Page 4] Internet-Draft A YANG Data Model for L1CSM February 2023 entity owned by higher-layer service department (e.g., L2/3 VPN) whereas the Network SDN Controller is the control/management entity responsible for Layer 1 connectivity service. The CEs in Figure 2 are L2/3 devices that interface with L1 PE devices. +----------+ | Service | | SDN | |Controller| |/EMS/NMS | | for L2/3 | +----------+ | | | +--------------------+ | | | +----------+ | | | Network | | | | SDN | | | |Controller| | | | /EMS/NMS | | | | for L1CSM| | | +----------+ | | | | | +----+ +----+ +----+ +----+ | CE |--------| PE |..............| PE |------| CE | +----+ +----+ +----+ +----+ | | | | | | | | | +--------------------+ | | | | | | |<------------------>| | | Provider Network | | For Layer 1 | |<------------------------------------------>| Provider Network for L2/3 Figure 2: L1CSM SDN Controller/EMS/NMS-Based Service Model: Internal Customer Lee, et al. Expires 6 August 2023 [Page 5] Internet-Draft A YANG Data Model for L1CSM February 2023 The benefit is that the same Layer 1 transport network resources are shared by multiple services. A large capacity backbone network (data plane) can be built economically by having the resources shared by multiple services usually with flexibility to modify topologies, while separating the control functions for each service department. Thus, each customer can select a specific set of features that are needed to provide their own service [RFC4847]. 1.2. Terminology Refer to [RFC4847] and [RFC5253] for the key terms used in this document. 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]. 1.3. Tree Diagram A simplified graphical representation of the data model is used in Section 3 of this this document. The meaning of the symbols in these diagrams is defined in [RFC8340]. Lee, et al. Expires 6 August 2023 [Page 6] Internet-Draft A YANG Data Model for L1CSM February 2023 1.4. Prefixes in Data Node Names In this document, names of data nodes and other data model objects are prefixed using the standard prefix associated with the corresponding YANG imported modules. The module ietf-layer1-types specified in [I-D.ietf-ccamp-layer1-types] is imported in this module. +-------------+-------------------+------------------------------+ | Prefix | YANG module | Reference | +-------------+-------------------+------------------------------+ | l1csm | ietf-l1csm | [RFCXXXX] | | l1-types | ietf-layer1-types | [RFCYYYY] | +-------------+-------------------+------------------------------+ Table 1: Prefixes and Corresponding YANG Modules Note: The RFC Editor will replace XXXX with the number assigned to the RFC once this document becomes an RFC. The RFC Editor will replace YYYY with the number assigned to the RFC once [I-D.ietf-ccamp-layer1-types] becomes an RFC. 1.5. Abbreviations L1VC Layer 1 Virtual Connection UNI User Network Interface PE Provider Edge CE Customer Edge 2. L1CSM YANG Model Overview The L1CSM describes the Layer 1 connectivity services following the convention defined in [MEF63] which includes the description of User Network Interface (UNI) access characteristics and L1 virtual connection (L1VC) service characteristics: Lee, et al. Expires 6 August 2023 [Page 7] Internet-Draft A YANG Data Model for L1CSM February 2023 +--rw l1-connectivity +--rw access | +--rw unis | +--rw uni* [id] | +--rw id string | ....................................... +--rw services +--rw service* [service-id] +--rw service-id string .......................................... The UNI access characteristics can be specified using either the definitions in [MEF63], which are based on the 3-tuple includes protocol, coding and optical-interface, or the definitions in [I-D.ietf-ccamp-layer1-types], which are based on the client signals in [ITU-T_G.709]: +--rw (uni-access-type)? +--:(mef) | +--rw protocol identityref | +--rw coding identityref | +--rw optical-interface identityref +--:(itu) +--rw client-signal identityref The L1VC service characteristics are described by references to a list of L1VC end points. For point-to-point connectivities, only two end points are allowed. +--rw endpoint* [endpoint-id] +--rw endpoint-id string +--rw uni -> /l1-connectivity/access/unis/uni/uni-id 3. L1CSM YANG Model (Tree Structure) Lee, et al. Expires 6 August 2023 [Page 8] Internet-Draft A YANG Data Model for L1CSM February 2023 module: ietf-l1csm +--rw l1-connectivity +--rw access | +--rw unis | +--rw uni* [uni-id] | +--rw uni-id string | +--rw (uni-access-type)? | +--:(mef) | | +--rw protocol identityref | | +--rw coding identityref | | +--rw optical-interface identityref | +--:(itu) | +--rw client-signal identityref +--rw services +--rw service* [service-id] +--rw service-id string +--rw endpoints +--rw endpoint* [endpoint-id] +--rw endpoint-id string +--rw uni -> /l1-connectivity/access/unis/uni/uni-id 4. L1CSM YANG Code <CODE BEGINS> file "ietf-l1csm@2023-02-01.yang" module ietf-l1csm { yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:ietf-l1csm"; prefix "l1csm"; import ietf-layer1-types { prefix "l1-types"; reference "RFCYYYY: A YANG Data Model for Layer 1 Types"; } // Note: The RFC Editor will replace XXXX/YYYY with the number // assigned to the RFCs once this draft becomes an RFC. organization "Internet Engineering Task Force (IETF) CCAMP WG"; contact "WG Web: <https://datatracker.ietf.org/wg/ccamp/> WG List: <mailto:ccamp@ietf.org> Lee, et al. Expires 6 August 2023 [Page 9] Internet-Draft A YANG Data Model for L1CSM February 2023 Editor: Young Lee <mailto:younglee.tx@gmail.com> Editor: KwangKoog Lee <mailto:kwangkoog.lee@kt.com> Editor: Haomian Zheng <mailto:zhenghaomian@huawei.com> Editor: Oscar Gonzalez de Dios <mailto:oscar.gonzalezdedios@telefonica.com> Editor: Daniele Ceccarelli <mailto:daniele.ietf@gmail.com>"; description "This module describes L1 connectivity service based on MEF 63: Subscriber Layer 1 Service Attribute Technical Specification. Refer to MEF 63 for all terms and the original references used in the module. Copyright (c) 2023 IETF Trust and the persons identified as authors of the code. All rights reserved. Redistribution and use in source and binary forms, with or without modification, is permitted pursuant to, and subject to the license terms contained in, the Revised BSD License set forth in Section 4.c of the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info). This version of this YANG module is part of RFC XXXX; see the RFC itself for full legal notices."; revision "2023-02-01" { description "Initial revision."; reference "RFC XXXX: A Yang Data Model for L1 Connectivity Service Model (L1CSM)"; } /* * Groupings */ grouping protocol-coding-optical-interface { description Lee, et al. Expires 6 August 2023 [Page 10] Internet-Draft A YANG Data Model for L1CSM February 2023 "The 3-tuple <p,c,o> where p:protocol type; c:coding function; o:optical interface function. Valid combinations are defined in Tables 4, 5, 6 and 7 of MEF 63."; reference "MEF63: Subscriber Layer 1 Service Attributes"; leaf protocol { type identityref { base l1-types:protocol; } mandatory true; description "The protocol being used at the UNI."; } leaf coding { type identityref { base l1-types:coding-func; } mandatory true; description "The coding function being used at the UNI."; } leaf optical-interface { type identityref { base l1-types:optical-interface-func; } mandatory true; description "The optical interface function being used at the UNI."; } } grouping subscriber-l1vc-endpoint-attributes { description "Subscriber Layer 1 connection endpoint attributes"; reference "MEF63: Subscriber Layer 1 Service Attributes"; container endpoints { description "The container for the list of the subscriber L1VC end points"; list endpoint { key "endpoint-id"; min-elements 2; max-elements 2; Lee, et al. Expires 6 August 2023 [Page 11] Internet-Draft A YANG Data Model for L1CSM February 2023 description "The list of the two of the subscriber L1VC end points"; leaf endpoint-id { type string; mandatory true; description "The subscriber L1VC end point ID"; } leaf uni { type leafref { path "/l1-connectivity/access/unis/uni/uni-id"; } mandatory true; description "The UNI supporting the subscriber L1VC end point"; } } } } /* * Data nodes */ container l1-connectivity { description "Serves as a top-level container for a list of Layer 1 connection services (l1cs)"; container access { description "UNI configurations for access networks"; container unis { description "The list of UNIs to be configured"; list uni { key "uni-id"; description "UNI identifier"; leaf uni-id { type string; description "The UNI ID of UNI Service Attributes"; } choice uni-access-type { description "The UNI access type can be specified either by the protocol, coding function and optical interface function, defined in MEF, or by the client-signal, defined in ITU-T."; Lee, et al. Expires 6 August 2023 [Page 12] Internet-Draft A YANG Data Model for L1CSM February 2023 case mef { uses protocol-coding-optical-interface; } case itu { leaf client-signal { type identityref { base l1-types:client-signal; } mandatory true; description "The client signal being used at the UNI"; reference "ITU-T G.709 v6.0 (06/2020): Interfaces for the Optical Transport Network (OTN)"; } } } } } } container services { description "L1VC services"; list service { key "service-id"; description "A unique identifier of a subscriber L1VC service"; leaf service-id { type string; description "A unique service identifier for subscriber L1VC."; } uses subscriber-l1vc-endpoint-attributes; } //end of service list } //end of service container } //service top container } <CODE ENDS> 5. Security Considerations The YANG module specified in this document defines 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]. Lee, et al. Expires 6 August 2023 [Page 13] Internet-Draft A YANG Data Model for L1CSM February 2023 The NETCONF access control model [RFC8341] provides the means to restrict access for particular NETCONF or RESTCONF users to a preconfigured subset of all available NETCONF or RESTCONF protocol operations and content. A number of configuration data nodes defined in this document are writable/deletable (i.e., "config true") These data nodes may be considered sensitive or vulnerable in some network environments. These are the subtrees and data nodes and their sensitivity/ vulnerability: uni: - uni-id service: - service-id - endpoint-id The security considerations spelled out in the YANG 1.1 specification [RFC7950] apply for this document as well. 6. IANA Considerations This document registers the following URIs in the "ns" subregistry within the "IETF XML Registry" [RFC3688] as follows: URI: urn:ietf:params:xml:ns:yang:ietf-l1csm Registrant Contact: The IESG XML: N/A; the requested URI is an XML namespace. This document registers following YANG modules in the YANG Module Names registry [RFC7950]. name: ietf-l1csm namespace: urn:ietf:params:xml:ns:yang:ietf-l1csm prefix: l1csm reference: RFC XXXX Lee, et al. Expires 6 August 2023 [Page 14] Internet-Draft A YANG Data Model for L1CSM February 2023 7. Acknowledgements The authors would like to thank Tom Petch for his helpful comments and valuable contributions and Robert Wilton for his review that improved the model significantly. 8. Contributors Italo Busi Huawei Technologies Email: Italo.Busi@huawei.com Giuseppe Fioccola Huawei Technologies Email: giuseppe.fioccola@huawei.com Dhruv Dhody Huawei Technologies Email: dhruv.ietf@gmail.com 9. References 9.1. Normative References [I-D.ietf-ccamp-layer1-types] Zheng, H. and I. Busi, "A YANG Data Model for Layer 1 Types", Work in Progress, Internet-Draft, draft-ietf- ccamp-layer1-types-15, 23 November 2022, <https://www.ietf.org/archive/id/draft-ietf-ccamp-layer1- types-15.txt>. [ITU-T_G.709] International Telecommunication Union, "Interfaces for the optical transport network", ITU-T G.709, June 2020. [MEF63] Metro Ethernet Forum, "Subscriber Layer1 Service Attributes Technical Specification", MEF 63, August 2018. [RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, DOI 10.17487/RFC3688, January 2004, <https://www.rfc-editor.org/info/rfc3688>. [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>. Lee, et al. Expires 6 August 2023 [Page 15] Internet-Draft A YANG Data Model for L1CSM February 2023 [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>. [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>. [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>. [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>. 9.2. Informative References [RFC4847] Takeda, T., Ed., "Framework and Requirements for Layer 1 Virtual Private Networks", RFC 4847, DOI 10.17487/RFC4847, April 2007, <https://www.rfc-editor.org/info/rfc4847>. [RFC5253] Takeda, T., Ed., "Applicability Statement for Layer 1 Virtual Private Network (L1VPN) Basic Mode", RFC 5253, DOI 10.17487/RFC5253, July 2008, <https://www.rfc-editor.org/info/rfc5253>. [RFC8199] Bogdanovic, D., Claise, B., and C. Moberg, "YANG Module Classification", RFC 8199, DOI 10.17487/RFC8199, July 2017, <https://www.rfc-editor.org/info/rfc8199>. [RFC8309] Wu, Q., Liu, W., and A. Farrel, "Service Models Explained", RFC 8309, DOI 10.17487/RFC8309, January 2018, <https://www.rfc-editor.org/info/rfc8309>. Appendix A. JSON Example This section provides a JSON example of the YANG module described in Section 4. This example configures one L1VC service with two UNIs that describe the connection endpoints. Lee, et al. Expires 6 August 2023 [Page 16] Internet-Draft A YANG Data Model for L1CSM February 2023 { "ietf-l1csm:l1-connectivity": { "access": { "unis": { "uni": [ { "uni-id": "MTL-HQ-Node3-Slot2-Port1", "protocol": "ietf-layer1-types:Ethernet", "coding": "ietf-layer1-types:ETH-10GR", "optical-interface": "ietf-layer1-types:LR-PMD-10G" }, { "uni-id": "MTL-STL-Node5-Slot4-Port3", "protocol": "ietf-layer1-types:Ethernet", "coding": "ietf-layer1-types:ETH-10GR", "optical-interface": "ietf-layer1-types:ER-PMD-10G" } ] } }, "services": { "service": [ { "service-id": "Sub-L1VC-1867-LT-MEGAMART", "endpoints": { "endpoint": [ { "endpoint-id": "MTL-HQ_1867-MEGAMART", "uni": "MTL-HQ-Node3-Slot2-Port1" }, { "endpoint-id": "MTL-STL_1867-MEGAMART", "uni": "MTL-STL-Node5-Slot4-Port3" } ] } } ] } } } Authors' Addresses Lee, et al. Expires 6 August 2023 [Page 17] Internet-Draft A YANG Data Model for L1CSM February 2023 Young Lee Samsung Samsung Seoul South Korea Email: younglee.tx@gmail.com KwangKoog Lee Korea Telecom South Korea Email: kwangkoog.lee@kt.com Haomian Zheng Huawei Technologies H1, Huawei Xiliu Beipo Village, Songshan Lake Dongguan Guangdong, 523808 China Email: zhenghaomian@huawei.com Oscar Gonzalez de Dios Telefonica Email: oscar.gonzalezdedios@telefonica.com Daniele Ceccarelli Cisco Email: daniele.ietf@gmail.com Lee, et al. Expires 6 August 2023 [Page 18]