# Industrial IoT Monitoring: Technologies and Architecture Proposal
## 3 WSN Diagnostic Tools
### Network Tools  
The nature of wireless communications makes this technology unreliable and failure-prone. In this context, diagnostic tools that are able to collect network metrics and evaluate the state of the network are essential. Three types of approaches can be used to collect network information: (1) passive, using extra hardware to collect network information without interference; (2) active, using on-node available resources; and (3) hybrid, using a mix of active and passive approaches.  
When passive approaches are used, the acquisition of network-related information is made by installing extra sniffer nodes or sniffer capabilities in the existing sink nodes. These diagnostic tools may differ in the type of sniffer nodes, in the storage approach, and in the way the gathered information is transmitted. Specifically, some of the existing solutions use sink sniffer nodes to collect traffic data from the network; others use extra networks of sniffers deployed with the main WSN; others use sniffer nodes that collect data and store it in memory; and, lastly, the most expensive in terms of network installation, send network-related information by wired technologies (e.g., SNIF [55], SNTS [56], PDA [57], LiveNet [58] and L-SNMS [59]).  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Standard**} & **Modeling** & \multirow{2}{*}{**Supported Operations**} & **Resource Constrained** & **Notifications** & \multirow{2}{*}{**Used Protocols**} \\  & **Language** & & **Devices Support** & & & \\ \hline \multirow{2}{*}{SNMP} & \multirow{2}{*}{SMlv2} & Monitoring/Configuration & \multirow{2}{*}{No} & \multirow{2}{*}{Yes} & \multirow{2}{*}{UDP} \\  & & & & & \\ \multirow{2}{*}{SNMP} & \multirow{2}{*}{SMlv2} & Monitoring/Configuration & \multirow{2}{*}{No} & \multirow{2}{*}{No} & \multirow{2}{*}{SSH/SSL/HTTP} \\  & & & & & \\ \hline \multirow{2}{*}{RETCONF} & YANG & Monitoring/Configuration & Yes & Yes & HTTP/TLS/TCP \\ \hline \multirow{2}{*}{COMI} & YANG/SMIv2 & Monitoring/Configuration & Yes & Yes & CoAP/DTLS/UDP \\ \hline \multirow{2}{*}{LWM2M} & \multirow{2}{*}{XML/YANG} & Monitoring/Configuration/ & \multirow{2}{*}{Yes} & \multirow{2}{*}{Yes} & CoAP/DTLS/UDP \\  & & Application Management & & & and SMS \\ \hline \hline \end{tabular}
\end{table}
Table 3: Network management protocols revision.  
Differently from passive tools that rely on extra hardware to monitor the network, active approaches use on-node metrics already available in sensors nodes. Active tools are easy to install, do not need extra hardware and, consequently, are less expensive when compared to passive approaches. However, active tools may have impact on node resources, as memory, energy, processing, and network throughput are needed to collect, store, and transport network-related information. Some of the tools gather traffic metrics from the sensor nodes' operating system, others from the network layer, and others directly from sink nodes, based on the received network traffic. In addition, there is a specific set of tools that use software scripts deployed in sensor nodes to collect statistics about the network traffic seen by the node. Subsequently to data acquisition, the transport of network-related information can be made using the main application channel or a secondary channel. To minimize the impact of data transport, some tools use compression and aggregation techniques so as to reduce the traffic overhead. Examples of this type of tools are Marionete [60], Megs [61], Memento [62], Wringer [63], 6 PANview [50], and D2 [53].  
Lastly, hybrid approaches use a mix of methods described in the cases of the active and passive approaches. Examples of this type of tools are Sympathy [64] and Dustminer [65].