1. OSI Layer

The student is using her modem to connect to the public network before being able to connect to the UTeM facilities. From the UTeM network, the data then was forwarded to UTeM IT Center where the Ulearn System server is located.

- Physical Layer

The lowest layer of OSI model is concerned with the electrically or optically transmitting raw unstructured data bits across the network from the physical layers of the receiving device. Devices and network components that are associated with the physical layer, for example, the antenna and amplifier, plug and socket for the network cable, the repeater, the stroke, the transceiver, the T-bar and the terminator.

- Data Link

At the data link layer, directly connected nodes are used to perform node-to-node data transfer where data is packaged into frames. The data link layer also corrects errors that may have occurred at the physical layer. The data link layer encompasses two sub-layers of its own. The first media access control (MAC), provides flow control and multiplexing for device transmissions over a network. The second, logical link control (LLC), provides flow and error control over the physical medium as well as identifies line protocols.

- Network

The data transfer between two different networks will be facilitated by the network layer. The network layer is responsible for receiving frames from the data link layer, and delivering them to their intended destinations based on the addresses contained inside the frame. The network layer finds the destination by using a logical address, such as IP (Internet Protocol). At this layer, routers are a crucial component used to route information where it needs to be between networks. In this layer, the destination of the Ulearn System server will be determined by using its logical address.

- Transport

The transport layer is in charge of transferring data from one process to another. The duties in the transport layer are port addressing, segmentation and reassembly, connection control, flow control and error control. The data in this layer is called Segments. In this layer, when a student uploads a file to the Ulearn System, the transport layer adds the port address to the header of the file. After that, the data will experience the segmentation and reassembly. This layer receives messages from the session layer and breaks it down into smaller pieces. A header is connected with each segment that is created. In the destination station, the message will be reassembled. Transport layer header will include a type of address which is service point address or port address to send messages to the correct process. Thus, the transport layer ensures that the message is delivered to the relevant process by supplying the address.

- Session

The session layer is responsible for maintaining, establishes and synchronizes the interaction between communicating systems. From the scenario, the student wants to access the Ulearn System, so the connection is made between the UTeM student’s home network and the server. When the student inserts the login information such as matric number and password, the server will check the user’s credential. Next, the session layer will control and synchronize the conversation to ensure that data streams are appropriately marked. Then, the data streams will be resynchronized to avoid the message ending being severed prematurely and prevent data loss. Lastly, the session layer also includes dialogue control that allows two systems to communicate in half-duplex or full-duplex mode.

- Presentation

The presentation layer is responsible for syntax and semantics of the information exchanged between two systems. The presentation layer is also known as the translation layer. This layer will receive data from the application layer. The data will be retrieved and processed here in order to transmit it over the network in the correct format. For example, this layer will convert the data from ASCII to EBCDIC. Furthermore, data encryption will convert the data into different formats or code. The encrypted data is called a ciphertext and the plain text is the decoded data. For both encrypting and decrypting data, a key value is used. In addition, the compression also occurs in the presentation layer, which minimizes the number of bits that must be broadcast across the network.

- Application

The application layer which is implemented by network applications is at the top of the OSI Reference Model stack of layers. The application layer is responsible for providing services to the user. These applications generate data that must be transmitted over the network. The application layer also acts as a window for the application services to connect to the network and show the information they receive to the user. For better understanding, this layer delivers end-user network services. For example, once a UTeM student has successfully accessed the Ulearn System, the student will be able to browse the portal which contains a variety of services from which they can choose.

The flow of how data travels from the student’s computer to reach the Ulearn System server which is in the UTeM IT Center:

The data flows via the seven layer of OSI model to allow human-readable information to be sent from one device to another. The figure below are some of the probable network components involved in the communication.

For example for the situation when the student is uploading the answer's file via Ulearn. The procedure begins first on the student’s PC. The student’s file answer or raw data will be passed to the application layer via the file application when the student uploads the file. The data format and file transfer protocol (FTP) will be specified by the application layer and the data will be passed to the presentation layer.

The data format will be standardized at the presentation layer and the encryption process will be finished if necessary. We need to check the communication connection type to see if it is encrypted or not. The data is then compressed and passed to the session layer by the presentation layer. The compression will aid in the uploading of data in terms of speed and efficiency.

The communication session will be started during the session layer by sending requests and responses between the application layer and the transport layer. It determines whether or not the proposed session is valid. If affirmative, the data is passed on to the next layer.

Following that, the data is sent to the transport layer. The transport layer provides multiplexing during this stage, allowing the host to send and receive error-corrected data via the TCP and UDP protocols. At the network layer, flow and error control will be conducted and the data will be segmented and then broken up into packets.

The network layer will be used to facilitate the transfer of data from the public network that is connected to the student’s computer to the UTeM network that is connected to UTeM IT Center. The network layer will route packets by discovering the best physical path to be used to transport the packets to the destination node and the IP address of the UTeM network will be used to route packets. This is referred to as routing, and it takes place at the router.

The packets will be split down into frames and transferred to the physical layer when they reach the data link layer. The frames will be transformed to a 0s and 1s bitstream and sent through a physical medium like a cable. The data will then be saved in the Ulearn System Server which is housed in the UTeM IT Center. On the student’s computer, data transmission in the physical layer occurred through a modem which is responsible to modulate and demodulate the analog signal from the public network and the digital signal from the router, and other network devices, so that the student’s computer can connect to the public network.