## 4 NetAR Mobile Application Design  
NetAR was designed based on an image target that the mobile device can identify and track, in order to superimpose the AR on it [59]; the same image target was used for all the developed scenes. Each scene had its own movements and animations and was developed in such a way that the users can view the scene in 360 degrees by moving their mobile device at different angles. The project focused on the design of sketches and animation ideas that could then be programmed with the AR Unity application development tool. This software streamlined the creation of visual learning content by integrating tools such as a 2D and 3D figure viewer, a scenario control system, support for importing external packages and models, and an error compiler into a single development platform. NetAR was developed for mobile devices with Android operating system. The purpose of the application was to provide a series of AR scenes focused on networking topics (ISO/OSI model and static routing). It was designed to be intuitive and easy to navigate for the user; user response times depend on the resources of the mobile device used. The application provides several facilities to users as it is user-friendly, and by presenting information in a visual way, it is easier for users to learn and retain that information compared to using textbooks. The animations are presented simultaneously with audios that explain the general topic being covered and subtitles, displayed at the bottom of the screen, that serve to facilitate the understanding of the topics involved and allow hearing-impaired users to understand what is happening in the animations. Once the user starts the NetAR application, a menu appears on the screen. The menu has the option to select the desired topics, which can be seen in Table 1. In addition, there is a help option that shows a manual explaining the basic operation of the application. In the settings option, the user can turn the volume up or down as desired. NetAR has two main levels designed to deliver information on two relevant topics in the networking area (ISO/OSI model and static routing):  
Level 1. This first level was developed for students who have never studied or do not know the concepts of networking and the ISO/OSI model. At this level, the basic concepts of data networks are studied and the layers of the ISO/OSI model are analyzed. In Figure 2 of NetAR, the seven layers of the ISO/OSI model can be appreciated and the way in which \begin{table}
\begin{tabular}{l p{284.5 pt}} \hline \hline \multicolumn{1}{c}{**Subjects**} & \multicolumn{1}{c}{**Description**} \\ \hline ISO/OSI model & Shows the seven layers of the OSI model, with the example of sending a message. \\ Segment & Shows the parts that are added to the message before it goes to the packet. \\ Packet & Adds the necessary components to the message so that it can go into the packet. \\ Frame & Consists of the final phase that the message goes through before it is received. \\ Means of transmission & Presents the different means that exist for the transmission of information. \\ Access methods & Indicates the ways in which network devices can be accessed. \\ IP addressing & Shows the packet of information passing from the sender to the receiver. \\ Static routing & The direction that packets take when being sent from one device to another, considering the IP address of the next hop. \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Subjects used for the construction of NetAR. the information travels from the origin to the destination can be observed. Furthermore, NetAR shows the construction of the different protocol data units (PDU), all this using AR for a better understanding. Level 2. The second level was developed for students who have an understanding of the OSI model and the fundamental concepts of networking. The subject of this level, as can be seen in Figure 3, involves how to route data from source to destination using static routing protocols.