This deliverable reports on the activities of WP2 during the first year of the B5G-OPEN project. The work was split into two activities with the following objectives: • Defining use cases, service requirements and the network architecture in a generic way and more specific cases that will be used as guidelines to the project. • Providing reference network topologies and architecture to be used in the project for experimentation and performance evaluation. These objectives have been fully achieved and the B5G-OPEN network concept has been fully defined, thus providing a clear framework upon which to base and steer the activities in the other technical work-packages. One of the major aspects is the definition and clarification of the project key features, i.e. multi-band (MB) operation, optical continuum (closely related to the concept of domain-less network), integrated access, E2E network orchestration, and autonomous operation. A High-Level network view has proved very useful for many of the activities done within WP2 and a mapping of the 3 operators’ networks has been carried out along with terminology convergence. This document briefly reports on future types of services relevant to the B5G-OPEN network concept and related performance KPIs that are described around the dimensions of bandwidth, time, security, AI, and multi-network integration. Two specific Use Cases have been analysed and used to derive traffic matrices. The first one is a network service and related to access integration and describes how to use LiFi as an access technology along with WiFi and fixed line optical access. The second one develops a volumetric video service in a Digital Twin use case, which can potentially require an extremely high network capacity connectivity. A layered architecture where IP/MPLS termination and processing is performed at relevant central offices has been defined showing the relevant network technologies enhanced thanks to the introduction of the optical multi-band technology that allows optical bypass and thus the optical continuum. Two network architectures have been specifically proposed and preliminary investigated, based on either vertical or horizontal organization of resources. The former vertical approach appears, at this stage, as the most relevant one since it includes features that might be anyway required also for the alternative horizontal approach. This includes the need for new models and procedures for standardized multi-domain impairment-aware path computation, provisioning, and recovery, also encompassing packet-optical white boxes. The document reports on an analysis made of different access technologies and how they may fit into the B5G-OPEN network concept leading to an initial proposal of short-, medium, and long-term node architectures. The control plane is a key part of the B5G-OPEN concept and a starting point architectural fundaments are presented. The control plane is based on an architecture that performs service and network operations E2E from the Access Point to the Cloud node, which might include monitoring and AI/ML, and is also based on IBN and zero-touch networking paradigms, with autonomous operation built using closed-control loops at various levels, from device to network. The control plane, empowered by a distributed AI/ML-based engine, which performs data collection and intelligent aggregation, analysis, and autonomous operation acting on the network components, will enable coordinated decision-making across domains. The biggest piece of work in WP2 has been the definition of the reference network topology and traffic characterisation. A reference network topology has been defined that can be used for the validation studies. A traffic characterization methodology is also defined that can be used for different activities such as planning, dimensioning, and techno-economic studies. The methodology provides a procedure to generate traffic scenarios combining mass market services with other innovative services foreseen in the B5G-OPEN scope. A preliminary traffic analysis study on a realistic operator network example has been carried out. Total traffic volumes conveyed by different CO types under different adoption scenarios for both mass market and B5G-OPEN services are evaluated from short to long-term scenarios. The final activity reported in this deliverable tries to clarify the performance KPIs of the project and investigate how it relates to the KPI’s cartography of the 5G-PPP.