# Industrial IoT Monitoring: Technologies and Architecture Proposal
## 4 Proposed Architecture
### Gateway Monitoring Agent  
The gateway monitoring agent is the component in charge of representing management objects data in a standardised way, and of sending network monitoring data to the management systems. This agent also deals with data from multiple standards. The gateway monitoring agent is independent from the sensor node monitoring agent, thus allowing the separation of sensor node data collection from network monitoring data collection. In this context, gateway monitoring agents must meet the follow requirements: network monitoring should not significantly increase the cost of equipment nor the cost of installation; collecting network metrics should add low overhead to the gateway; monitoring  
\begin{table}
\begin{tabular}{|c|c|c|c|c|c|} \hline
**Standard** & \begin{tabular}{c} **Time** \\ **Standard** \\ \end{tabular} & \begin{tabular}{c} **Fragmentation and** \\ **Ressembly** \\ \end{tabular} & **Security** & \begin{tabular}{c} **Service Level Agreement** \\ **(Available Optional) Support** \\ \end{tabular} & \begin{tabular}{c} **Service Level Agreement** \\ **(Recommended) Protocols** \\ \end{tabular} \\ \hline ZigBee & - & Application Sub-Layer & & - & - \\ \hline WirelessHART & UTC & Block transfer service & & Publish, Event, Maintenance, & Publish service \\ \hline ISA100.11a & TAI & Network Layer & \begin{tabular}{c} Symmetric encryption \\ available in all standards \\ and supported by \\ IEEE802.15.4 hardware \\ \end{tabular} & \begin{tabular}{c} Contract type: periodic and \\ non-periodic Contract priority: \\ best-off request, real-time and \\ sequential, real-time buffer and \\ network control \\ \end{tabular} & Contract type: Non-periodic \\ \hline WIA-PA & UTC & Network Layer & \
\begin{tabular}{c} Publish/subscribe VCRs, \\ source/sink VCRs, \\ and client/server VCRs \\ \end{tabular} &
\begin{tabular}{c} Source/sink VCR or \\ Client/server VCR \\ \end{tabular} \\ \hline \end{tabular}
\end{table}
Table 4: Network transport revision.  
should be energy-efficient; the monitoring solution should be easy to install and should be extensible; and, lastly, gateway monitoring agents should support widely used industrial standards, namely the ones addressed in this paper.  
Considering the three types of techniques identified in Section 3.1 (active, passive, and hybrid), active type techniques are the only ones that are easy to install and do not rely on extra hardware to perform monitoring tasks. However, these types of techniques usually consume sensor node resources, as pointed in Section 3. On the other hand, in Section 2, the revision made to the metrics shared between nodes showed us that the standards under consideration can support the sharing of critical information related to network and sensor node state, which can be used for resource allocation and routing tasks. Thus, by using these metrics, active tools will be capable of fulfilling the identified requirements without spending significant sensor node resources. Furthermore, some current industrial solutions available on the market already provide these metrics at the gateway, using proprietary libraries. The only disadvantage of active type techniques is the partial coverage in ZigBee networks because some metrics cannot be gathered by the coordinator. This arises from the fact that, in ZigBee, route computation is done in a distributed fashion for some topologies.