# Future Industrial Networks in Process Automation: Goals, Challenges, and Future Directions
## 3 Technology Enablers for Future Control Architecture
### Tsn  
TSN is a set of IEEE 802 Ethernet substandards that have been developed by the Time-Sensitive Networking task group of the IEEE 802.1 working group [12] with the aim to enable deterministic real-time communication over Ethernet. TSN achieves determinism over Ethernet using a set of tools that can be partitioned into four main domains of (i) time synchronization, (ii) bounded low latency, (iii) ultra reliability, and (iv) resource dedication. Table 1 lists a number of standards developed in each of these four domains. Time synchronization deals with timing and synchronization; in other words, it provides the network with synchronized clocks. 802.1 AS-Rev is the main standard in this domain. The Bounded low latency domain is responsible for the determinism, which guarantees data availability at the expected time by applying different scheduling and forwarding techniques. The Ultrareliability domain targets the reliability of the system, and focuses on the errors, faults, and redundancy techniques to keep the system dependable. The Resource dedication and application programming interface (API) domain enables the high-level planning and configuration required to allow systemwide feature capabilities in heterogeneous networks. The ongoing work on TSN promises hard real-time capabilities. It is also claimed that TSN can reserve the bandwidth exactly according to the application latency requirement and consequently enables the convergence of different networks into one common network that transmits time-sensitive control data together with best-effort data and data with soft real-time requirements. Although this can be seen as a real game-changer for real-time automation applications, it is still unclear how to efficiently select a set of TSN Standards and tune the relevant settings. In order to derive and develop technical solutions that will enable a transition towards an information-centric architecture, we need to consider how the process industries are established and evolving to stay profitable and competitive. The most obvious scenario that comes to mind is when a brand new production site is built. In this scenario, the automation system providers are competing with their latest and most advanced products and system solutions that solve the site owner's needs. This is referred to as a green-field installation. Another scenario in process automation, probably the most common scenario, where the \begin{table}
\begin{tabular}{c c c} \hline \hline
**Area of Definition** & **Standards** & **Title of Standards** \\ \hline
**Timing synchronization** & 802.1 AS & Timing and Synchronization \\ \hline \multirow{5}{*}{**Bounded low latency**} & 802.1 Qav & Credit-Based Shaper \\ \cline{2-3}  & 802.1 Qbu & Frame Preemption \\ \cline{2-3}  & 802.3 br & \\ \cline{2-3}  & 802.1 Qbv & Scheduled Traffic Enhancement \\ \cline{2-3}  & 802.1 Qch & Cyclic Queuing and Forwarding \\ \cline{2-3}  & 802.1 Qcr & Asynchronous Traffic Shaping \\ \hline \multirow{5}{*}{**Ultrareliability**} & 802.1 CB & Frame Replication and Elimination \\ \cline{2-3}  & 802.1 Qca & Path Control and Reservation \\ \cline{2-3}  & 802.1 Qci & Per-Stream Filtering and Policing \\ \cline{2-3}  & 802.1 AS-Rev & Enhancement and performance \\ \cline{2-3}  & 802.1 Qat & Stream Reservation Protocol \\ \cline{2-3}  & 802.1 Qcc & Stream Reservation Protocol/ \\ \cline{2-3}  & 802.1 Qcc & TSN configuration \\ \cline{2-3}  & 802.1 Qcp & YANG Data Model \\ \cline{2-3}  & 802.1 CS & Link-local Registration Protocol \\ \hline \hline \end{tabular}
\end{table} 
Table 1: A short list of IEEE Time-Sensitive Networking (TSN) Standards. API—application programming interface. company is long-time established with one or more large-scale production sites. Those established companies are most often either modernizing or extending their production capacities or product ranges. In this scenario, there is already a large installed base of automation equipment, as well as existing network infrastructures, in place. This is referred to as a brown-field installation.