Deliverable D3.4 is the second deliverable dealing with the implementation of the Interworking Layer (IWL). This deliverable includes all IWL components as they are tested and integrated internally and with other 5G EVE components (5G EVE Portal, 5G EVE sites), as we describe in the deliverable D3.7. One of the biggest efforts done in the scope of WP3 during the last third of the second year of the project is the integration of the IWL components. We integrated and tested the components first internally, and later with the other 5G EVE components of the 5G EVE Portal and the 5G EVE sites. Most of this integration has been done during the COVID-19 situation, which impacted the normal execution of the project due to the restrictions on working physically in the sites. However, we delivered in time the IWL components with the required scope and now IWL is integrated with the 5G EVE Portal and we tested the integration with OSM and ONAP NFV-Os. As we explain in the Roadmap section, we managed the scope of the IWL roadmap for delaying those part that are not essential today for the project, without impacting the services and features offered by 5G EVE. In addition, we also managed the incorporation of new requirements: (i) a new Gaming use case coming from Telefonica and incorporated in the last amendment of the project, (ii) new requirements for integrating a new kind of orchestrators that are focused in RAN management and (iii) the development of a new component, called IWL repository, which exposes information related to the architecture of the 5G EVE sites. The seamless incorporation of these new requirements demonstrates that the open and modular IWL architecture allows to change, evolve or enhance any part of the IWL for adapting it to future requirements. We also update in this report the information related to inter-site connectivity, which is core for supporting the multi-site experiments execution.