# Towards Flexible Integration of 5G and IIoT Technologies in Industry 4.0: A Practical Use Case
## 4 Proposed Architecture  
This section focuses on the description of the proposed architecture that is intended to meet the first two objectives of this work: the deployment of the NFV- and SDN-enabled architecture for Industry 4.0, and the inclusion of a WSN for IIoT applications. For this purpose, the components and operation of the SN4I experimental facility are described, in addition to how the WSN has been implemented. As introduced before, SN4I is an NFV- and SDN-enabled experimental facility deployed across the Faculty of Engineering in Bilbao (EIB) and the Aeronautics Advanced Manufacturing Center (CFAA). These two locations are interconnected through a layer-2 SDN network at a rate of 10 Gbps. Both datacenters are equipped with the hardware and software components that enable the deployment of virtual services in the infrastructure, leveraging NFV technology. The complete infrastructure comprises several SDN switches and servers, amounting to a total computing and storage capacity of around 250 dual-threaded cores, 1 TB of RAM, and 25 TB of storage. Two OpenStack nodes deployed in EIB and the CFAA manage the resources of their respective locations, and three ONOS controllers manage, respectively, the data plane connectivity in the EIB domain, the CFAA domain, and the Wide Area Network between both locations. Finally, an Open Source MANO on top orchestrates the whole NFV and SDN infrastructure. A high-level view of the SN4I infrastructure is shown in Figure 6.  
In addition, a WSN has been integrated into this architecture, enabling the deployment of several constrained sensors in the CFAA in order to monitor different environmental parameters such as temperature, humidity, or lightness. The aim of this network is to implement different IIoT applications in the CFAA using Hidra as the access control protocol. Different protocols are used within the WSN, which are suitable for IIoT applications and devices. These protocols are IEEE 802.15.4 [37], 6 LoWPAN [38] and RPL [39]. The interconnection between the WSN and the wired SN4I is performed through a 6 LoWPAN Border Router, which is implemented by means of a Raspberry Pi running the necessary protocol translation and packet routing functions and a CDS connected to the Raspberry  
Figure 5: Hidra policy language structure. Pi in order to allow for the wireless transmission using the IEEE 802.15.4 protocol. The integration between the sensor network and the CFAA plant network is depicted in Figure 7.  
The SN4I infrastructure is designed in a way to ensure that different services are isolated from each other at both the computing level and the networking level, despite making use of a shared pool of physical resources. Not only does this address performance issues due to the contention of resources between different services, but also confidentiality and privacy issues with the data of  
Figure 6: Proposed Architecture. Figure 7: Integration of the Wireless Sensor Network (WSN) in the CFAA. different services. With this aim, the SN4I network is segmented at the layer-2 level into multiple isolated VLANs, with each of these resulting slices being allocated to a different NS. This kind of VLAN encapsulation also translates smoothly to OpenStack, as it can support the use of underlying VLAN networks by appropriately tagging the traffic of VMs. OpenStack also provides a separate IPv4/IPv6 layer-3 network for the VMs located in each of these VLAN-segmented slices. Each NS maps logically to a given manufacturing process and provides it, on demand, with the necessary resources and virtual services. This isolation between NSs ensures the avoidance of data filtration between different processes. Furthermore, by configuring the corresponding rules and policies in the associated ONOS controller, it can be ensured that machine tools that are physically connected to one of these slices are similarly isolated from other slices and from the rest of the network. The process to create a new NS can be summarized as follows.