0733-8724 (c) 2019 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information. This article has been accepted for publication in a future issue of this journal, but has not been fully edited. Content may change prior to final publication. Citation information: DOI 10.1109/JLT.2019.2941320, Journal of Lightwave Technology > REPLACE THIS LINE WITH YOUR PAPER IDENTIFICATION NUMBER (DOUBLE-CLICK HERE TO EDIT) < 1 Abstract— The need of introducing interoperability in the transport network segment has motivated the emergence of several open initiatives and standardization efforts for the development of different interfaces to allow Software Defined Network (SDN) controllers manage and control the network devices. Optical disaggregation in particular aims the introduction of standard device-level interfaces in the optical terminals and line-systems to ‘open’ them from vendor lock-in situations, allowing an interoperable ecosystem in the optical network’s transport segment. In this article, it is firstly presented the Software Defined Transport Network (SDTN) architecture, as the control and management framework to build a L0-L3 multi-layer, multi- technology transport network, enabling end-to-end network service delivery. Later, we introduce the partially disaggregated network architecture proposed, including the technical assessment of the topology discovery and resilience service provisioning use cases, by providing a low-level description of the information models employed and the translation between models. To conclude, a proof-of-concept of multi-layer service provisioning over resilient disaggregated multi-vendor testbed is presented, including the results obtained in the experimental demonstration presented in last 2019 Optical Fibre Conference (OFC). Index Terms— SDTN, Optical Partial Disaggregation, Optical Transport, OpenConfig, ONF TAPI, IETF L2SM. This manuscript was submitted for peer review to the Journal of Lightwave Technology (JLT) on June 21st, 2019. The paper was supported in part by the European Commission H2020-ICT-2016-2 METRO-HAUL project (G. A. 761727). Moreover, we would like to acknowledge Arista team for their support during the test. A. Mayoral is with the Signal Theory and Communications Dept. of the Universitat Politècnica de Catalunya (UPC), 08034 Barcelona, (e-mail: arturo.mayoral@upc.edu). V. López, M. López-Bravo, D. Garcia-Montes, O. González de Dios and J.P Fernández-Palacios are with Telefónica I+D/Global CTO, Distrito Telefónica, Edificio Sur 3, Planta 3, 28050 Madrid, Spain (e-mail: victor.lopezalvarez@telefonica.com, oscar.gonzalezdedios@telefonica.com, juanpedro.fernandez-palaciosgimenez@telefonica.com). A. Aguado is with the Center of Computation and Simulation of the Universidad Politécnica de Madrid, Campus Montegancedo, 28660 Boadilla del Monte, Madrid, Spain (e-mail: a.aguadom@fi.upm.es). R. Szwedowski and K. Mrówka are with ADVA Optical Networking, (e- mail: RSzwedowski@advaoptical.com, KMrowka@advaoptical.com). F. Marques and Z. Stevkovski are with Infinera (e-mail: FaMarques@infinera.com, ZStevkovski@infinera.com). D. Verchere is with Nokia Bell-Labs, France (e-mail: Dominique.Verchere@nokia-bell-labs.com). L. Tancevski is with Nokia, Germany (e-mail: lubo.tancevski@nokia.com). I. INTRODUCTION A ny transport network is composed by multiple segments, consisting of different technologies and network layers (e.g. IP/MPLS, Optical). The standardization work allows a homogeneous control framework to progressively get rid of traditional vendor-proprietary Network Management Systems (NMSs), whilst reducing the existing vendor lock-in in the management plane. Optical networks are the basis of the Telecommunications Operators (TELCOs) transport infrastructure at the different aggregation levels (metropolitan, regional and long-haul). The TELCOs’ deployments in the different regional areas are commonly single vendor, due to the complexity of optical networking, the lack of low-level interoperability and the enhanced network operability. By introducing standard interfaces and data models into heterogeneous vendor devices, management applications can uniformly define the services to be deployed in the network independently of the underlying network infrastructure. This separation is one of the critical concepts introduced by the SDN paradigm. This separation between network infrastructure and control and management systems and network customer applications, allows independent evolution of the two worlds through the implementation of a common, standard and stable management interface between them. The approach presented in this paper is based in the Software Defined Transport Architecture (SDTN) concept presented by the authors in [1], which is depicted in Fig.1. This hierarchical SDN architecture allows Operation Support Systems (OSS) and other SDN customer applications, such a service orchestrator like Open Source Mano (OSM) [2], the instantiation of abstract network services into the network, through the SDTN solution hierarchy. Once services are requested to the SDN layer through the NorthBound Interface (NBI), the SDTN Controller automatically performs all the tasks needed to set up the configuration in the network, e.g., mutli-layer path computation, resource availability discovery, capacity provisioning in the transport layers and the service provisioning itself, by applying the necessary network configuration either directly into the network equipment or through the mediation of SDN domain controllers (SDNc). On the other hand, the Optical Disaggregation concept aims Multi-layer service provisioning over resilient Software-Defined partially disaggregated networks A. Mayoral, V. López, M. López-Bravo, D. García-Montes, O. Gonzalez-de-Dios, A. Aguado, R. Szwedowski, K. Mrówka, F. Marques, Z. Stevkovski, D. Verchere, Q. Pham-Van, L. Tancevski, J-P. Fernandez-Palacios