# A Novel Framework for Cross-Cluster Scaling in Cloud-Native 5G NextGen Core
## 4 Open5 Gs and UERANSIM Configuration  
_Proposed Test Scenario_  
In our setup, the 5G network services deployment follows the Open5 GS implementation, whereas, for the emulation of the gNB and user configuration, we employ the RAN simulator, UERANSIM [18]. In addition, we run the 5G network functions as CNFs in the Open5 GS deployment, which are hosted in separate VMs across two different data centers (DCs) (each VM has allocated 4 cores and 8 GB RAM) in a public cloud environment running in different data centers of a European hyperscaler public cloud provider. The first DC is located in Berlin, and the capacity for transmitting data to and from the internet is 200 Gbps, while the second DC is in the UK and has a capacity of ten times lower than the first DC [70]. In our example, we display in Figure 2 three established network slices corresponding to three RAN schedulers for which the 5G mobile core functions are required: one instance of AMF, SMF, UPF, etc. microservices running on behalf of the first slice and the other two instances of each of the Open5 GS network functions running on behalf of the other two slices. These three deployments are able to scale independently based on their respective workloads and QoS service guarantees. The three network slices serve different application demands, for instance, based on the configured SSD values. The 3 GPP specifies a standard set of network slices, called standardized slice type (SST) values. The value of 1 for SST corresponds to eMBB, which is suitable for the handling of 5G enhanced mobile broadband applications such as streaming of high-quality video, large file transfers, etc. The SST value of 2 is suitable for the handling of URLLC communications for applications including industrial automation and remote control systems, whereas the SST value of 3 is suitable for handling massive IoT devices efficiently and cost-effectively [71]. These values dictate the use cases for verticals; for instance, the values for latency (<100 ms) can cover a multitude of performance requirements that require real-time applications (for instance, smart energy applications [1; 72]. Firstly, we create a 5G mobile network (internet reachable) for simulation to set up an environment in which packets can be sent end-to-end with different DNs (data networks)  
Figure 2: Deployment scenario for end-to-end network slicing. for each DNN (data network name), which is the equivalent of access point name (APN) in LTE. For example, APN does not have any control over the radio access network, whereas network slicing can control the configurations not only for the APN path but for the radio access path as well. In our configuration, the control plane serves multiple user planes, whereas the user plane is connected to multiple DNNs. Secondly, in our scenario, we distribute the traffic as follows: we connect 10 users to DN slice 1, another 10 users are connected to the DN corresponding to slice 2, and the last 10 users are connected to the DN configured for slice 3. This information is also registered in the Open5 GS WebUI. Finally, the deployment of Open5 GS is achieved in a declarative manner using Helm charts [73], specifically using YAML templates. In Kubernetes, the configmap represents an API object that stores the key-value pairs, which follows a similar pattern for environment variables. For the configmap of UPF and SMF, we specify the three DN subnet addresses and the corresponding DNN values. We also set three ReplicaSet for the UPF deployment. On each UFP, we need to configure the three ogstu interfaces along with the DN values. In the configmap for AMF, we specify the SST and SD values. The output of the two cluster provisioning processes consists of two kubeconfig files that contain credentials used to interact with the Kubernetes API server of the workload cluster. Another tool that we employ in our deployment is kubectl, which is an SDK client used to consume access to the Kubernetes API server.