## 6 Discussion
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Deployment** & **Customization** & **Maintenance** & **Scalability** & **Reliability** & **Latency** \\ \hline \multirow{6}{*}{\begin{tabular}{c} SNPN and \\ on-premises edge \\ deployment \\ (Section 3.1) \\ \end{tabular} } & High flexibility & & & & \\  & (e.g., direct & & & & \\  & hardware access) & High effort & & & Ultra-low latency \\ on-premises edge & Specific features & (due to & Moderate & High reliability can & can be achieved \\ deployment & can be used & self-managed & (hardware limited) & be achieved & due to on-premises \\ (Section 3.1) & (e.g., virtualized & deployment) & & & & deployment \\ \hline \multirow{6}{*}{\
\begin{tabular}{c} On-premises edge \\ deployed on \\ shared NPN \\ infrastructure \\ (Section 3.2) \\ \end{tabular} } & Depending on the \\  & edge service model & (e.g., self-managed & & & Medium & High reliability can & & can be achieved \\  & vs. PaaS) & vs. PaaS) & & & & deployment \\ \hline \multirow{6}{*}{
\begin{tabular}{c} PNI-NPN + MNO \\ hosted edge \\ (Section 3.4) \\ \end{tabular} } & Limited, depends & & & & & \\  & on the PaaS that is & & Low effort & & & \\  & offered by MNO or & (managed & & Depending on & \\  & third-party edge & Kubernetes by & High & MNO hosted edge & Low latency can \\  & provider & edge service & & infrastructure & be achieved \\  & (e.g., limited access & provider) & & capability & \\  & to hardware & & & & capability \\  & resources) & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Main characteristics of the integration scenarios of NPN deployment models and edge computing options. better performance isolation for selected pods to serve sensitive workloads by partitioning the Kubernetes nodes and running such workloads only on nodes tuned for low latency. However, as Kubernetes is highly customizable, this is viable, but still, common industrial extensions, add-ons that provide platform-level solutions for the problems could drive the usage of Kubernetes better in industrial edge computing environments. For example, to launch multiple application instances with intrinsic data replication between them either in hot standby or active-active resiliency mode and provide a single service to hide them from the device side, could be a desirable service construction object in industrial environments. It also must be noted that when a service is deployed in an edge computing environment, the configuration of the edge cloud features, including the internal networking and the networking (5G connectivity) between the edge computing platform and the devices, has to be done together. Considering the integration of the edge computing reliability method with TSN FRER, one main finding is that, currently, the Kubernetes-provided failover methods are not suitable for industry-grade applications, so multiple active application instances have to be deployed in the edge. From the industry device capability perspective, two alternatives can clearly be identified: (1) the device can simultaneously handle multiple application instances, and (2) the industry can handle only a single application instance. The multiple application instances handling scenario fits to greenfield deployments or for such cases when the device software is written in a way to be able to handle multiple application instances. The main drawback of this option from the viewpoint of legacy deployment is that the industrial end device software has to be adapted to the simultaneous communication towards multiple application instances. In this case, the end-to-end reliability can be provided on a per-domain basis by properly configuring the placement of the application and TSN FRER instances in the edge domain and the disjoint paths for the TSN streams in the TSN domain. It is important to mention that in this scenario, reliability can be provided even without TSN FRER; in such a case, each stream between the device and an application instance has to be configured by the CNC to use independent paths in the TSN domain.